264results about How to "Avoid measurement effects" patented technology

The invention relates to the technical field of measuring parameters of a transmission line of a power system, in particular to a method for measuring positive sequence parameters of an ultra-high voltage transmission line based on double end measuring information. The method comprises: measuring positive sequence impedance and positive sequence capacitance of the transmission line; when measuring the positive sequence impedance of the transmission line, cutting off the to-be-measured transmission line, performing three-phase short connection to the tail end of the transmission line, adding athree-phase voltage on the front end of the transmission line; when measuring the positive sequence capacitance of the transmission line, cutting off the to-be-measured transmission line, performing three-phase opening to the tail end of the transmission line, adding the three-phase voltage on the front end of the transmission line; using a global satellite positioning system technology to simultaneously measure the three-phase voltage on two ends of the transmission line and the three-phase current on two ends of the transmission line, and synchronously sampling the three-phase voltage and three-phase current. The method in the invention solves the influence of the distributed capacitance on the transmission line to the positive sequence parameters measurement so as to greatly increase the precision of the positive sequence parameters measuring result of the transmission line.

The invention discloses a permanent magnet synchronous motor parameter identification method, which belongs to the technical field of synchronous motor parameter testing. A current or voltage pulse vector whose direction is the same as that of A-phase axis of a motor stator is inputted to the permanent magnet synchronous motor, a voltage excitation signal with a zero average voltage and containing a non-zero voltage pulse is inputted between the B phase and the C phase of the permanent magnet synchronous motor, and current of each phase of the permanent magnet synchronous motor during the process is sampled; according to three-phase current obtained through sampling in the case of steady three-phase current of the motor, the inputted current or voltage pulse vector and parameters of the excitation voltage signal are combined, and stator resistance, d-axis inductance and q-axis inductance of the permanent magnet synchronous motor are calculated and obtained. The invention also discloses a permanent magnet synchronous motor parameter identification device and a control system. Influences on d-axis and q-axis inductance measurement by d-axis positioning errors can be avoided, quickness of current sampling is not required, and measurement accuracy is better.

The invention belongs to the liquid level instrument, in particular to a built-in pressure tapping method of a differential pressure type level gauge, which at least comprises a liquid storage tank (5), a differential pressure type level gauge (1), a positive phase pressure guiding pipe (2) and a negative phase pressure guiding pipe (3); the positive phase pressure guiding pipe (2) and the negative phase pressure guiding pipe (3) are respectively connected with a positive end and a negative end of the differential pressure type level gauge (1). The invention is characterized in that: a vertical section of the negative phase pressure guiding pipe (3) is arranged inside a vessel, liquid contained by the vessel is prearranged into the negative phase pressure guiding pipe (3), the invention can remove the influence on measuring due to vapor or medium temperature variation in the vessel, meanwhile, the structure is simple, the operation is easy and the maintenance cost is low.

The invention provides a CCD device quantum efficiency measuring device and method. The device comprises a CCD device absolute quantum efficiency measuring apparatus and a CCD device relative quantum efficiency measuring apparatus, the CCD device absolute quantum efficiency measuring apparatus is used for measuring the absolute quantum efficiency of a CCD device on a 632.8 nm wavelength point, and the CCD device relative quantum efficiency measuring apparatus is used for measuring the relative quantum efficiency of the CCD device within the wavelength range from 300 nm to 1100 nm. According to the CCD device quantum efficiency measuring device and method, a 632.8 nm laser is used for emitting light into an integrating sphere to carry out absolute calibration after the light passes through a power stabilizing system, lasers with different levels of output power can be selected according to different CCD devices, the problem that optical power is low is avoided, no light loss is caused, a standard detector directly traces the source to a low-temperature radiometer on the 632.8 nm wavelength point, and therefore the number of intermediate links is reduced, and uncertainty of measurement is improved.

The invention discloses a determination instrument and determination method for osmotic coefficients of a drilling and coring test part, aiming at effectively avoiding influences of lateral wall seepage, determining the osmotic coefficients of common rock soil bodies and porous concrete and further determining the osmotic coefficients of a drilling and coring test part of the rock soil bodies before and after grouting. The technical scheme of the determination instrument is as follows: the determination instrument comprises a water outlet buffering region, a testing cavity and a water inlet buffering region which are arranged in sequence from top to bottom; the water outlet buffering region, the testing cavity and the water inlet buffering region are fixedly connected to form a sealed cavity; a water outlet is formed in the upper end of a lateral wall of the water outlet buffering region; an exhaust hole is formed in the top of the water outlet buffering region; a water inlet is formed in the lower end of the lateral wall of the water inlet buffering region; in a testing process, a testing part is arranged in the testing cavity; a seepage-proof layer is arranged between the test part and an inner lateral wall of the testing cavity; water permeable layers are arranged at the upper and lower ends in the testing cavity; in the testing process, the testing part is located between the water permeable layers at the two ends and is in contact with the water permeable layers.

The invention discloses a flow measuring device for a partially filled pipe drainage pipeline. The measuring device is a separated type structure, the device comprises a streamline probe and a flowmeter host, and the streamline probe is connected with the flowmwter host through a waterproof cable; the streamline probe is a totally-enclosed waterproof structure, wherein the front end of the streamline probe is provided with a first underwater acoustic transducer and a second underwater acoustic transducer in parallel, the top end is provided with a third underwater acoustic transducer, the bottom of the probe is provided with a pressure transmitter, and the back end is provided with a temperature sensor; the flowmeter host comprises an ultrasonic Doppler flow rate measuring module, ultrasonic liquid level measuring module, a pressure transmitter measuring module, a temperature measuring module, an FPGA operational module, an MCU main control module, a battery and voltage-stabilized source module, a GPRS communication module and a debugging interface circuit. According to the device, through the separated type structure of integrating the streamline probe with five sensors and the host, the problems are simplified that the flowmeter installation and maintenance are difficult.

The invention discloses an aging site rapid diagnosis method for a 10 kV XLPE cable based on the polarization current measurement. According to the technical scheme of the invention, the Harmon approximation algorithm is improved when the fitting parameter n of the relaxation current is larger than or equal to 0 and smaller than or equal to 0.3, or is larger than or equal to 1.2 and smaller than or equal to 2. In this way, the application range of the Harmon approximation algorithm is expanded and the measurement time of the polarization current is greatly shortened according to the frequency range of a dielectric loss factor tan Delta determined based on the field actual need. Moreover, based on the improved Harmon approximation algorithm, the dielectric loss factor tan Delta at a corresponding frequency can be quickly and intuitively obtained, so that the cable aging condition can be judged based on the value of the dielectric loss factor tan Delta at the corresponding frequency. Therefore, by adopting the aging site rapid diagnosis method for the 10 kV XLPE cable based on the polarization current measurement, the aging condition of a field cable can be rapidly diagnosed. At the same time, the method is wider in application range and can reflect the cable aging condition more accurately. The requirement of the field time measurement can be met.

The invention discloses a system for measuring the nanometer micrometric displacement based on full-fiber frequency domain interference. A broadband light source of the system is connected with a port I of an optical fiber circulator through an optical fiber, a port II of the optical fiber circulator is connected with one end of a silica optical fiber probe through the optical fiber, a port III of the optical fiber circulator is connected with an optical spectrometer through the optical fiber, and tail fibers of components are connected through a flange plate or in a welding method. The system disclosed by the invention has the ability of measuring the nanometer micrometric displacement, is a non-contact type measuring device, can be used for statically and dynamically measuring the distance from the surface of an objected to be tested to the surface of the probe, and can be used for measuring metal or nonmetal. According to the system disclosed by the invention, by adopting a full-fiber-structured device, the operation difficulty is greatly reduced, the promotion and the use of the device are facilitated, and the anti-interference ability is strong.

The invention discloses an optical system wavefront measurement device and method based on a circular carrier frequency phase demodulation method. The device comprises a laser, a beam expander, a spatial filter, an optical system to be measured, a point diffraction plate and a CCD camera, wherein the laser, the beam expander, the spatial filter, the optical system to be measured, the point diffraction plate and the CCD camera are sequentially coaxially arranged in the direction of an optical path; the spatial filter is arranged on the focus of the beam expander; the point diffraction plate is arranged on an emergent wave surface rendezvous point of the optical system to be measured; the point diffraction plate comprises a pin hole and a pin hole peripheral part, and the pin hole peripheral part is plated with a high-reflection film layer. The measurement method includes the steps that before an ideal wave surface generated by the point diffraction plate through the pin hole diffraction effect is used as a reference wave, the point diffraction plate moves in the direction of the optical axle to form a circular carrier frequency interferogram, and a four-phase splice method is utilized to directly solve original phases in the circular carrier frequency interferogram, namely the wavefront of the optical system to be measured. According to the method, the emergent wavefront of the optical system can be measured by few components, and the measurement device is easy to operate, high in accuracy and capable of meeting the requirement of transient measurement.

The invention discloses a testing method for the thermal positioning error of a linear axis of a vertical machining center. This method first measures the positioning error of each measuring point of the linear axis of the vertical machining center at the initial moment, that is, the geometric error, and then measures the positioning error of each measuring point of the linear axis of the vertical machining center at any time, and the conditions remain unchanged during the two measurements , and finally make a difference between the two data to obtain the thermal positioning error of each measurement point of the linear axis of the vertical machining center at any time. In this way, the influence of the geometric errors of the various components of the machine tool on the thermal positioning error measurement is avoided, and the accuracy of the measurement results is improved. This method can quickly and efficiently complete the on-machine test requirements of the thermal positioning error of the linear axis, which not only avoids the influence of the geometric errors of the various components of the machine tool on the measurement of the thermal positioning error, but also avoids the use of displacement sensors or standard parts as well as clamping, finding The deviation problem caused by positive and fixed improves the accuracy of the measurement results.

An automatic control system of mechanical press features that the rotary transformer is used as the sensor of crankshaft angle and slide blockí»s stroke, its encoder is the sensor of die height regulation, and the minimal single-chip computer system with the special control software is used for the logic control to overall units of mechanical press and their functions. Its advantages are simple structure and high reliability.

The invention discloses a semi-trailer positioning and measuring system which comprises a traction-shaft central-line clamping apparatus, a crossbeam central-point clamping apparatus and a tyre-center positioning device. When in measurement, the traction-shaft central-line clamping apparatus is arranged on a traction shaft of a crossbeam, a hanger of the crossbeam central-point clamping apparatus is hung on the measured crossbeam and positioned between the traction shaft and a closest bridge, the tyre-center positioning device is sequentially placed on a tyre at the outer side of each measured bridge, a rim central-clamping jaw of the tyre-center positioning device is clamped on a shaft sleeve positioned in the rim of the tyre at the outer side of each bridge and ensures that the center thereof is superposed with the center of the rim central-clamping jaw, and laser is irradiated onto a scale plate through a light passing hole by adjusting the position of a laser emitting pipe of the tyre-center positioning device; a light spot is beaten on a scale mark '0', which indicates that the bridge is vertical to a reference line and does not need to be adjusted; and if the light spot is not positioned at the '0' position of the scale mark, the bridge is adjusted according to the offset position of the light spot. The system can avoid the influence on measurement due to the geometric model changes, such as the deformation of the crossbeam or the dislocation of the bridge, and the like and ensure the accuracy of measurement.

The invention discloses a high-precision seawater sound velocity measuring method based on optical frequency comb interference. The method comprises the following steps: a high-precision seawater sound velocity measuring optical path based on optical frequency comb interference is set up, so that a precise displacement platform continuously moves so as to change the optical distance of an interference optical path and a first reflection optical path; oscilloscope measurement data are collected; moment points t1 and t2 at which the optical distance of the interference optical path are equal tothe optical distance of the measuring optical distance and a reference optical path separately are obtained according to interference fringes at optical frequency combs A and B; the number of continuous light interference fringes between t1 and t2 is calculated, thereby determining the flight distance of sound waves; and the flight time of sound waves is calculated according to a sudden change oflight intensity caused by a pulse acousto-optic effect. The high-precision seawater sound velocity measuring method based on optical frequency comb interference takes the optical frequency comb interference and the pulse acousto-optic effect as fundamental principles to detect a seawater sound velocity profile, and aims at realizing sound velocity measurement with high accuracy and high stability.