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48results about How to "Easy to implement programmatically" patented technology

Modular industrial robot reconstruction system and control method thereof

InactiveCN107471206AImprove performanceGive full play to the matching connection abilityProgramme-controlled manipulatorProduction lineConfiguration selection
The invention discloses an open type reconstructive modular intelligent industrial robot reconstruction system; equipment is simple in structure, lower in cost, smaller in size, high in openness, long in service life and low in power consumption; the configuration selection and the reconstruction control can be effectively performed on a reconstructive modular robot; the terminal use portability and practicability are improved; the user upgrading cost is reduced; and the user use experience is improved. Meanwhile, the invention further provides a corresponding reconstruction system control method; the method is simple, liable to operate and high in accuracy, can preferably satisfy quick reconstruction demands in production by a flexible production line, enables the system to achieve easy expansion and customization through relative reconstruction and independence, improves the reliability and the maintainability, and is convenient to upgrade the system; and intelligent joint modules can bring convenience for distributive control of all joints.
Owner:DALIAN JIAOTONG UNIVERSITY

Method for measuring large-stress range stress strain in uniaxial tensile test of metal plate sample

The invention relates to a method for measuring the large-stress range stress strain in a uniaxial tensile test of a metal plate sample. The method comprises the following steps: building a step modelfor gradual expansion of unstable necking of uniaxial tension of the metal plate sample; measuring the instant gauge length and the minimum sectional width at a necking position of the plate sample after extension instability; building an interpolation curve expression of the necking profile on the basis of necking step coordinates of the necking step model at each moment; solving the parametersof the necking step model according to the mechanical relationship of necking in the width direction and the thickness direction and the principle of volume conservation; finally calculating the actual stress and actual strain at the moment through a Bridgman method. By adopting the method, the test measuring link for the necking outer profile curvature radius in the existing method is omitted, and the measuring accuracy of a large-strain range stress-strain curve is improved, so that the method has important significance to the mechanical performance test of metal materials.
Owner:JILIN UNIV

Data selection method for calculating blunt round radius of cutting edge

ActiveCN105651200AImprove the efficiency of wear measurementEliminate errorsUsing optical meansData selectionEngineering
The invention provides a data selection method for calculating the blunt round radius of a cutting edge and belongs to the technical field of the geometric feature measurement for cutting tools, which relates to a data selection method for calculating the blunt round radius of a cutting edge. According to the technical scheme of the method, firstly, the profile of the cutting edge of a cutting tool is acquired based on the microscopic measurement method, and the data point curve of the profile of the cutting edge of the cutting tool is extracted. Secondly, the fitting calculation is conducted to successively approximate the straight lines of the front and back tool surfaces of the cutting cool based on the iterative method, so that the range of the fitting data points of the blunt round of the cutting edge can be obtained. Thirdly, the blunt round radius of the cutting edge, the left distance difference and the right distance difference of the cutting edge are calculated. The above fitting calculation process is repeated for iterative computation, till the left distance difference and the right distance difference meet the iterative terminating condition. According to the technical scheme of the invention, the error, caused by the uncertain range of the fitting data points of the blunt round of the cutting edge, can be eliminated. Based on the method, the blunt round radius of the cutting edge of the cutting tool can be calculated more accurately and more really through the fitting calculation process, and the programming is easier to implement. Moreover, the measurement efficiency for measuring the passivation abrasion of the blunt round of the cutting edge of the cutting tool is effectively improved.
Owner:DALIAN UNIV OF TECH

A method for automatically generating false comment dataset of Chinese commodity

The invention discloses a method for automatically generating a false comment data set of Chinese commodity, which comprises the following steps: a) reading the comment data collected in advance intoa memory; B) segmenting the comment by using a word segmentation tool to obtain a word sequence representation of the comment text; C) comparing the text similarity between two commodity reviews within a given range to obtain a false commodity review set Rf1; D) executing an associated query on the comments in Rf1 to obtain a product false comment result set R1; E) extracting the name informationof the commentator corresponding to the commodity comment within a given range; (f) analyzing that name of the commentator, finding out the name of a series of commentators conforming to a certain rule characteristic, executing an associated query on the false commentator, and obtaining a product false comment result set R2; G) finally, merging R1 and R2 to obtain the final false comment data setof the commodity. The invention fully automates the detection and identification of the false comment in the commodity comment data and automatically generates the false comment data set of the commodity without manual intervention and labeling.
Owner:ZHEJIANG GONGSHANG UNIVERSITY

Preparation method of gallic acid high grade alxoxide ester

A process for preparing the high-grade alkanol ester for gallic acid, whose chemical formula is (HO)3C6H2COOCnH2n+1, includes catalytic reaction between gallic acid, high-grade alkanol, and solvent at 105-125 deg.C, carrying to resultant vapour out of the reactor by the evaporated solvent, condensing, removing water by millpore ceramic column, returning solvent back to reactor, continuous circulation until reaction is terminated, and recrystallizing.
Owner:南京龙源天然多酚合成厂

Virtual screening method of human transthyretin (hTTR) disturbing chemicals

The present invention discloses a virtual screening method of human transthyretin (hTTR) disturbing chemicals, belonging to the field of methods of screening environmental endocrine disturbing chemicals. According to the virtual screening process, firstly, chemicals are classified based on ten radical groups, then a disturbing effect of each chemical on the hTTR is predicted by using a quantitative structure-active relationship model, so that whether the chemical has a capability of disturbing transport of the thyroxine by the hTTR is determined according to a predicted effect value, and the strength of the disturbing capability is also determined. The process of screening the hTTR disturbing chemicals is simple and reasonable, and the method is accurate and reliable, is easy to be programmed, and can be applied to virtual screening of potential hTTR disturbing chemicals in an application domain and priority setting of potential disturbing chemicals.
Owner:DALIAN UNIV OF TECH

Method for obtaining transverse wave time difference section through logging and core data

The invention discloses a method for obtaining a transverse wave time difference section through logging and core data. The method comprises the following steps that (A) a target well is layered and sectioned according to lithologic characteristics; (B) the logging data of the target well and the core rock mechanical testing data of a corresponding target well section of the target well or each well adjacent to the target well are prepared; (C) the data are collated, and an observation input matrix, parameter column vectors and output column vectors are built; (D) a cubic Householder matrix isbuilt, and the observation input matrix and the output column vectors are subjected to cubic transformation; (E) a linear system of equations is built according to the transformed observation input matrix and the output column vectors, and the parameter column vectors are solved; and (F) the transverse wave time difference section of the target well is calculated according to the logging data. The method is specific to a horizontal well or a directional well which is lack of transverse wave time difference data, according to the logging data and the core rock mechanical testing data, the transverse wave time difference section of the target layer section is predicted accurately, the ill-conditioned problem in the solving process can be solved, the basis is provided for obtaining mechanical parameters subsequently, and exploiting of the target well is promoted.
Owner:SOUTHWEST PETROLEUM UNIV

Arc backstepping measuring method of uniaxial stretch-strain of metal round bar test specimen

The invention relates to an arc backstepping measuring method of uniaxial stretch-strain of a metal round bar test specimen, and belongs to the technical field of metal material mechanical property testing. The arc backstepping measuring method is based on an arc rotating body model with step-by-step expansive uniaxial stretching instability necking of the metal round bar test specimen, scale distance elongation in the stretching process of the round bar test specimen is only needed to be measured, coordination information of the outer contour of the test bar after breaking is extracted, and arc radius of necking and minimum cross section radius of necking at each moment are calculated through backstepping and directly substituted into a Bridgman algorithm to calculate real stress and realstrain at the moment. According to the arc backstepping measuring method, the test and measuring link of the minimum cross section radius of necking and the curvature radius of the outer contour in an existing method are eliminated, measuring precision of a stress-strain curve of a large strain range is improved, and the arc backstepping measuring method has significance for metal material mechanical property testing.
Owner:JILIN UNIV

Hybrid type automobile electrophoresis coating conveying mechanism dynamics modeling method

ActiveCN105159137AHas coordinate invarianceNeat and concise expressionProgramme controlSimulator controlHybrid typeDynamic models
The invention discloses a hybrid type automobile electrophoresis coating conveying mechanism dynamics modeling method. First of all, the symmetrical structure characteristic of a mechanism is fully utilized, the speed and the accelerated speed of each passive joint in the mechanism are analyzed through an analytical geometry method, and then the speed and the accelerated speed of each active joint of the mechanism are obtained by introducing a screw theory; secondly, based on this, a kinetic equation in a mechanism spinor form is established by use of virtual work principle; and finally, axial driving power of each active joint of the conveying mechanism capable of directly realizing control is obtained through calculation so that construction of a dynamics model capable of realizing high-performance control is completed. According to the invention, the analytical geometry method, the screw theory and the virtual work principle are combined together, so that the problem of coordinate transformation due to lack of coordinate invariance during dynamics modeling of a complex special mechanism is solved, the calculation complexity is reduced, and at the same time, the dynamics modeling method brought forward by the invention is quite simple, is tidy in form and is easy in programmed realization.
Owner:JIANGSU UNIV

Hyperbolic back-stepping measuring method of uniaxial tension stress and train of metal round bar specimen

The invention discloses a hyperbolic back-stepping measuring method of uniaxial tension stress and strain of a metal round bar specimen, and belongs to the technical field of mechanical property testing of metal materials. The method is based on a hyperbolic rotating body model of step-by-step expansion of uniaxial tension instability necking of the metal round bar specimen, and the standard distance elongation in the tensile process of the round bar specimen only needs to be measured, and coordinate information of the curve of the outer contour of the round bar specimen after breaking is extracted, a necking hyperbolic equation and a necking minimum section radius at each moment are calculated through back-stepping, thus the curvature radius of the minimum section at the necking positionat this moment can be obtained through a curvature radius formula, and finally, real stress and real strain at this moment can be calculated by a Bridgman method. According to the hyperbolic back-stepping measuring method, a testing and measuring link of the necking minimum section radius and the curvature radius of the outer contour in an existing method is omitted, the measurement accuracy of the stress and strain curve in a large strain range is improved, and the hyperbolic back-stepping measuring method has important significance for mechanical property testing of the metal materials.
Owner:JILIN UNIV

Singularity treatment method for six-degree-of-freedom articulated robot

The invention discloses a singularity treatment method for a six-degree-of-freedom articulated robot. The singularity treatment method comprises the following steps that (1) a kinematic model of the robot is built; (2) the six-degree-of-freedom articulated robot is subjected to rectangular coordinate space motion trail planning; (3) interpolating points of a motion trail are subjected to kinematicinverse solution, angles of joints of the robot at the interpolating points are obtained, and the angular speeds and angular acceleration of the joints of the robot at the interpolating points are obtained according to the relation between a jacobi matrix and a cartesian space as well as the relation between the jacobi matrix and a joint space; (4) the joint singularity condition is solved, and asingularity zone is obtained; and (5) the robot is made to smoothly pass through the singularity zone through singularity treatment. According to the singularity treatment method, the problem that the robot is subjected to singularity in the moving process, and thus, the joint angular speed is abruptly changed can be solved, accordingly, the motion smoothness of the robot is improved, and the angles and the angular speeds of the joints of the robot smoothly pass through the singularity zone.
Owner:HEFEI UNIV OF TECH

Method and system for optimizing and predicting dissolved oxygen based on hybrid QPSO-DE optimization

The invention discloses a method and a system for optimizing and predicting dissolved oxygen based on hybrid QPSO-DE, and the method comprises the steps: carrying out the optimization design of parameters of a support vector machine through employing a QPSO-DE algorithm, setting the support vector machine obtained through optimization design as an optimization prediction dissolved oxygen model, and obtaining dissolved oxygen prediction data. Compared with a standard differential evolution algorithm, the invention has the advantages that the search capability is stronger, the performance is better, individuals entering the next generation in each iteration have better fitness values, the premature phenomenon of the algorithm can be effectively avoided, that is, the algorithm falls into local optimum and cannot jump out, and the global search capability of the algorithm is improved.
Owner:FOSHAN UNIVERSITY

Method for constructing coordinate transformation matrix of multiphase motor under an open-phase fault

The invention discloses a method for constructing a coordinate transformation matrix of a multiphase motor under an open-phase fault, comprising the following steps: (1) constructing a basic vector group M0; (2) constructing a first harmonic vector group HI; (3) constructing a first specific irrelevant group MI; (4) determining and processing the first specific irrelevant group MI; (5) constructing a third harmonic vector group HIII; (6) constructing a third specific irrelevant group MIII; (7) determining and processing the third specific irrelevant groups MIII; (8) according to the method inthe steps (5) to (7), constructing a fifth harmonic vector group HV and a fifth specific irrelevant group MVs, and determining and processing the fifth specific irrelevant group MV; (9) analogizing according to the step (8). The method is easy to realize, and can quickly and accurately obtain the coordinate transformation matrix of any multiphase motor under any open-phase fault. The obtained coordinate transformation matrix can reduce the dimensionality of the multiphase motor, simplify the original model of the multiphase motor, and can be used for multiphase motor fault modeling, fault characteristic signal extraction, fault tolerance control.
Owner:HUNAN UNIV

Flexible spacecraft integrated modeling method

Provided is a flexible spacecraft integrated modeling method. A flexible spacecraft comprises flexible accessories and a central rigid body. The method includes the following steps of firstly, calculating the antithesis momentum of the flexible accessories relative to the mass center of the flexible spacecraft under dynamic conditions through a finite element method and an integration method underthe coordinate system of a flexible spacecraft body; secondly, calculating the antithesis momentum of the central rigid body relative to the mass center of the flexible spacecraft under dynamic conditions through the finite element method and the integration method under the coordinate system of the flexible spacecraft body; thirdly, summarizing the antithesis momentum of the flexible accessoriesrelative to the mass center of the flexible spacecraft in the first step and the antithesis momentum of the central rigid body relative to the mass center of the flexible spacecraft in the second step, and calculating the antithesis momentum of the flexible spacecraft relative to relative to the mass center of the flexible spacecraft under dynamic conditions; fourthly, calculating a flexible spacecraft posture orbit integrated kinetic equation according to the momentum theorem under the inertia coordinate system.
Owner:SHANGHAI AEROSPACE CONTROL TECH INST

Double star formation integrated modeling method

A double star formation integrated modeling method includes a first step of utilizing a finite element method and an integral method to calculate the dual momentum of a flexible attachment with respect to the centroid of a flexible body satellite under dynamic conditions; a second step of using the finite element method and the integral method to calculate the dual momentum of a first center rigidbody with respect to the centroid of the flexible body satellite under dynamic conditions; a third step of calculating the dual momentum of the flexible body satellite relative to the centroid of theflexible body satellite under dynamic conditions; acquiring an attitude track integrated kinetic equation of the flexible body satellite; a fourth step of using the finite element method and the integral method to calculate the dual momentum of a rigid body satellite relative to the rigid body satellite centroid under dynamic conditions; acquiring an attitude track integrated kinetic equation ofthe rigid body satellite; and a fifth step of acquiring a double star formation attitude track integrated kinetic equation according to the attitude track integrated kinetic equation of the flexible body satellite in the third step and the attitude track integrated kinetic equation of the rigid body satellite in the fourth step.
Owner:SHANGHAI AEROSPACE CONTROL TECH INST

Automatic measuring method for percentage elongation after single-shaft tensile fracture of metal round bar sample

The invention discloses an automatic measuring method for percentage elongation after single-shaft tensile fracture of a metal round bar sample and belongs to the technical field of mechanical property test of metal materials. According to the method, on the premise that the elasticity modulus and the poisson ratio of a material are known, only gauge length elongation and a load value at the tensile fracture moment of the round bar sample need to be measured and recorded, meanwhile, an optical method is adopted to collect the outer contour curve of the round bar sample after fracture, and thepercentage elongation after single-shaft tensile fracture of the metal round bar sample is obtained through elastic deformation analysis and calculation. According to the method, the elastic part is accurately deducted, without the need of identifying the fracture position in the gauge length range, a shifting method is automatically implemented, so that the percentage elongation after fracture isaccurately obtained. Compared with the existing manual measurement technology, tedious measurement links such as scribing and fixing the fracture sample are omitted, the measurement precision is improved, and great significance is achieved for mechanical property test of the metal material.
Owner:JILIN UNIV

A virtual screening method for human transthyretin interferents

The present invention discloses a virtual screening method of human transthyretin (hTTR) disturbing chemicals, belonging to the field of methods of screening environmental endocrine disturbing chemicals. According to the virtual screening process, firstly, chemicals are classified based on ten radical groups, then a disturbing effect of each chemical on the hTTR is predicted by using a quantitative structure-active relationship model, so that whether the chemical has a capability of disturbing transport of the thyroxine by the hTTR is determined according to a predicted effect value, and the strength of the disturbing capability is also determined. The process of screening the hTTR disturbing chemicals is simple and reasonable, and the method is accurate and reliable, is easy to be programmed, and can be applied to virtual screening of potential hTTR disturbing chemicals in an application domain and priority setting of potential disturbing chemicals.
Owner:DALIAN UNIV OF TECH

Bridge surface crack identification method based on image technology

The invention relates to a bridge surface crack identification method based on an image technology. The method comprises the following steps: acquiring image information of a bridge surface; three single-pixel width curves of the upper edge, the skeleton and the lower edge of the crack and three-dimensional coordinates of pixel points are obtained through pretreatment; respectively fitting curvilinear functions of the curves of the upper edge, the skeleton and the lower edge of the crack by adopting a three-point interpolation method, solving the crack width in the normal direction of pixel points on the skeleton curve and the second derivative of the curves of the upper edge and the lower edge of the crack, and respectively calculating the variance of the crack width and the second derivative; and multiplying by a corresponding weight coefficient and then adding to construct an authenticity discrimination coefficient, and identifying the authenticity of the crack on the surface of the bridge by setting an authenticity discrimination coefficient threshold value. According to the algorithm, the crack width change value and the edge curve concavity and convexity are used as main characteristic values for distinguishing the authenticity of the crack, the discrimination coefficient is constructed for authenticity identification, the calculation efficiency and the identification accuracy are high, and an effective guarantee is provided for quantitative evaluation of bridge surface concrete crack detection.
Owner:CHINA MERCHANTS CHONGQING COMM RES & DESIGN INST

Dynamics modeling method and system of space film diffractive imaging satellite

The invention discloses a dynamics modeling method and system of a space film diffractive imaging satellite. The method includes: acquiring the dual quaternion of the posture transformation among a satellite body coordinate system, an orbit coordinate system and a flexible appendage coordinate system; using a dual quaternion method to describe the dual momentum of a flexible appendage relative tothe flexible appendage coordinate system and the orbit coordinate system, the dual momentum of the central rigid body of a flexible satellite relative to the orbit coordinate system, the posture integrated dynamics model of the flexible satellite, and the integrated dynamics model of the flexible appendage relative to the central rigid body of the flexible satellite; describing the constraint pf the flexible appendage relative to the rotation of the central rigid body of the flexible satellite. The method has the advantages that the dynamics double-coupling relation of the flexible satellite is described compactly, calculation efficiency is increased, programming can be achieved easily, subsequent controller design is facilitated, and control precision is increased.
Owner:SHANGHAI AEROSPACE CONTROL TECH INST

A knn-based method for identifying the cause of ground faults in distribution networks

ActiveCN108983042BThe lean level of transportation inspection management is perfectPerfect level of leanFault location by conductor typesData ingestionFault occurrence
The invention provides a KNN-based distribution network ground fault identification method comprising steps of obtaining the zero-sequence current waveform data of different fault causes through an artificial grounding test or field actual fault recording, extracting five feature parameters representing the different fault causes and including the self-recovery, the transition time, the zero-current time, the distortion degree and the random degree to form a feature sample database; and when a fault occurs, calculating the above features of an input waveform and searching for a cause categoryof the fault by an KNN algorithm. The method, on the one hand, can focus on the fault cause before fault inspection so as to formulate a targeted inspection scheme, greatly improve fault finding efficiency and reduce power outage loss; on the other hand, can accurately obtain the distribution law of the distribution network fault causes of a certain supply area, creates hidden danger treatment andfault prevention measures, promotes the improvement in the level of distribution network operation and maintenance management, and improves the feature sample database with an increase in the numberof fault samples and features so as to achieve a high recognition success rate.
Owner:STATE GRID HUBEI ELECTRIC POWER RES INST +2

Method for automatic measurement of elongation after uniaxial tension of metal plate specimens

The invention discloses an automatic measurement method for the elongation rate of a metal plate sample after uniaxial tension, which belongs to the field of mechanical properties of metal materials. The method only needs to be measured and tested under the premise of known material elastic modulus and Poisson's ratio Record the gauge length elongation and load value at the moment of tensile fracture of the plate sample, and at the same time use optical methods to collect the distribution information of the outer contour of the plate sample in width and thickness, and obtain the uniaxial tension of the plate sample through elastic deformation analysis and calculation elongation after break. This method accurately deducts the elastic part, and automatically implements the displacement method without identifying the fracture position within the gauge length range, so as to accurately obtain the elongation after fracture. Compared with the existing manual measurement technology, it saves the cumbersome measurement links such as scribing and fixing the broken sample, and improves the measurement accuracy, which is of great significance for the mechanical performance test of metal materials.
Owner:JILIN UNIV

An Integrated Modeling Method for Flexible Spacecraft

An integrated modeling method for a flexible spacecraft, the flexible spacecraft includes flexible accessories and a central rigid body, comprising the following steps: Step 1, under the coordinate system of the flexible spacecraft body, using the finite element method and the integral method to calculate The dual momentum of the flexible attachment relative to the center of mass of the flexible spacecraft under dynamic conditions; step 2, in the coordinate system of the flexible spacecraft body, using the finite element method and the integral method, calculate the central rigid body relative to the flexible spacecraft under dynamic conditions The dual momentum of the center of mass; step 3, add the dual momentum of the flexible attachment relative to the center of mass of the flexible spacecraft in step 1 and the dual momentum of the central rigid body relative to the center of mass of the flexible spacecraft in step 2, and calculate the flexible spaceflight under dynamic conditions The dual momentum of the spacecraft relative to the center of mass of the flexible spacecraft; step 4, in the inertial coordinate system, according to the momentum theorem, calculate the dynamic equation of the flexible spacecraft attitude-orbit integration.
Owner:SHANGHAI AEROSPACE CONTROL TECH INST

A Coupling Network Generation Method for Loss and Temperature Rise of Water Internally Cooled Stator Transposition Winding

A coupling network generation method for loss and temperature rise of water internally cooled stator transposition windings of the present invention relates to the field of coupling networks between electrical and thermal networks in turbogenerators, the purpose of which is to overcome the existing problem of obtaining the temperature of braided transposition strands The calculation result of the method has a large error and the data is not accurate enough. The specific steps of the method are as follows: Step 1. Discrete the water-cooled stator transposition winding along the motor axis into multiple two-dimensional winding sections; Step 2. Divide each The winding section is discretized into multiple solid nodes and fluid nodes. Step 3. Calculate the resistance, reactance and thermal conductance at the first temperature; Step 4. Calculate the current and eddy current of each solid node according to the resistance and reactance; Step 5 , Calculate the loss of each solid node, and calculate the second temperature of each solid node and the temperature of the fluid node; Step 6, compare the second temperature with the first temperature, and generate the final water-cooled stator transposition winding Coupling network for loss and temperature rise.
Owner:HARBIN UNIV OF SCI & TECH

Space vector pulse width modulation (SVPWM) method based on coordinates

The invention discloses a coordinate-based SVPWM (Space Vector Pulse Width Modulation) method, which comprises the following steps of: (1) obtaining a target voltage vector in a dq rotating coordinate system according to a corresponding system structure, performing per unit processing, converting the target voltage vector to an alpha beta static coordinate system, and selecting two basic vectors according to a cost function; (2) the duty ratio is solved by using coordinates according to the geometrical relationship of the three; and (3) modulating and outputting an SVPWM signal according to the duty ratio and the basic vector state quantity. According to the method, a target vector is converted to a static coordinate system, a cost function is constructed, a basic vector required by synthesis of the target vector is selected through the cost function, and then a duty ratio required by synthesis is solved by converting a geometrical relationship of the vectors into an algebraic relationship between coordinates. And finally, the SVPWM signal is output by matching the on-off state corresponding to the basic vector with the duty ratio, so that the processes of sector judgment, vector decomposition, duty ratio sub-sector calculation and the like are omitted, the SVPWM modulation process is simplified, and the SVPWM modulation process is easier to realize in a programmed manner.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

Discrete-state-space-based small-signal stability analysis method for medium-voltage direct-current system

The invention discloses a small signal stability analysis method for a medium-voltage direct-current system based on a discrete state space, and belongs to the field of electrical engineering. The method comprises the following steps: deducing and establishing discrete state space models and discrete equivalent circuit models of direct current network elements and alternating current equipment elements in a system; constructing a discrete state space model and a discrete circuit network of the whole system according to the discrete equivalent circuit of each element and the topological structure of the system, and eliminating an intermediate variable of a state space equation based on the discrete circuit network to obtain a discrete state matrix; and according to the discrete state matrix of the system, solving a full-dimensional discrete characteristic value of the medium-voltage direct-current power system so as to analyze the small signal stability of the system. The method is clear in physical significance, programming is easy to achieve, compared with a traditional continuous state space analysis method, the topological structure of the system can be reserved, a calculation program is easy to modify when the topological structure of the system is changed, and the method is quite suitable for the medium-voltage direct-current power system with high reconfigurability.
Owner:HUAZHONG UNIV OF SCI & TECH +1

A Method for Constructing Coordinate Transformation Matrix of Multi-phase Motor Under Phase Loss Fault

The invention discloses a method for constructing a coordinate transformation matrix under a phase loss fault of a multi-phase motor, which includes the following steps: (1) Constructing a basic specific vector group M 0 ; (2) Construct the first harmonic vector group H Ⅰ ; (3) Construct a specific irrelevant group M once Ⅰ ; (4) Judging and processing a specific irrelevant group M Ⅰ ; (5) Construct the third harmonic vector group H Ⅲ ; (6) Construct three times specific irrelevant group M Ⅲ ; (7) Judging and processing the specific irrelevant group M three times Ⅲ (8) by the method of step (5) to step (7), construct the fifth harmonic vector group H Ⅴ , to construct five specific irrelevant groups M Ⅴ , judging and processing five specific irrelevant groups M Ⅴ ; (9) By analogy with step (8). The present invention is easy to program, and can quickly and accurately obtain the coordinate transformation matrix of any multi-phase motor under any phase loss fault. The obtained coordinate transformation matrix can reduce the dimension of the multi-phase motor, simplify the original model of the multi-phase motor, and can be used for multi-phase Motor fault modeling, fault characteristic signal extraction, fault-tolerant control.
Owner:HUNAN UNIV

A bridge deflection early warning method and system

The invention discloses a bridge deflection early warning method and system in the technical field of bridge structure early warning analysis, aiming to solve the problem that the deflection early warning threshold of the bridge health monitoring system in the prior art is relatively single, conservative, and has poor real-time performance, and misreporting of structural early warning information is prone to occur , False reporting, which is not conducive to ensuring the technical problems of bridge structure safety. The method comprises the following steps: obtaining deflection monitoring data, ambient temperature data, and vehicle crossing time information of the target bridge; dividing the deflection monitoring data into non-vehicle deflection data and passing deflection data based on the vehicle crossing time information, and calculating non-vehicle deflection data. The average value of the passing deflection data and the corresponding ambient temperature data in the preset period and the maximum value of the variation amplitude of each passing deflection data; the correlation analysis between the mean value of the non-passing deflection data and the corresponding ambient temperature data in the preset period ; Based on the correlation analysis results and the maximum value of the deflection change amplitude, the real-time deflection warning threshold of the target bridge is generated.
Owner:中铁桥隧技术有限公司

Arc Backward Measurement Method for Uniaxial Tensile Stress-Strain of Metal Round Bar Specimen

The present invention relates to the circular arc back-push measurement method of the uniaxial tensile stress and strain of metal round bar samples, and the technical field of testing the mechanical properties of metal materials. The circular arc rotating body model only needs to measure the elongation of the gauge length during the stretching process of the round bar sample, and extract the coordinate information of the outer contour curve of the broken test bar, and calculate the radius of the necking arc and the minimum necking at each moment by back-calculating The section radius is directly substituted into the Bridgman method to calculate the true stress and true strain at this moment. The invention omits the test and measurement link of the minimum section radius of the necking and the curvature radius of the outer contour in the existing method, and improves the measurement accuracy of the stress-strain curve in a large strain range, which is of great significance for the mechanical performance test of metal materials.
Owner:JILIN UNIV
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