45results about How to "Not easy to achieve" patented technology

The invention relates to an on-line ranging method for a 10kV cable based on the time-frequency composite analysis of the traveling wave of the sheath current, and belongs to the technical field of force system relay protection. First, extract the three-phase sheath current and I ∑ As a fault location signal; secondly, through the FFT-MUSIC algorithm to the fault location signal I ∑ Spectrum transformation is carried out to extract each frequency component in the traveling wave signal, and the rough measurement distance x of the fault is calculated by using the formula of the frequency difference method; finally, the preliminary location of the fault obtained by the frequency domain analysis method combined with the improved lumped empirical mode decomposition algorithm is used to analyze the signal Carry out time-domain analysis to accurately determine the arrival time of the second reflected wave head of the fault line, and then use the time difference between the reflected wave at the fault point, the reflected wave at the opposite end, and the initial wave head to achieve accurate fault location. The invention fully considers the electromagnetic effect of the cable sheath, uses the sheath current as the fault feature quantity, and improves the feasibility of online distance measurement.

The invention discloses an automatic inspection method for capacitance parameters in a circuit schematic diagram, which includes: deriving information from the circuit schematic diagram, extracting a power supply network; judging the resistance value of the resistor in the network; and judging the magnetic beads and inductance in the network , IC chip, if there are magnetic beads and inductance, it will be regarded as a short circuit. If there is no magnetic bead or inductance, other judgments will be made. If there is an IC chip, it will be regarded as an open circuit. If there is no IC chip, other judgments will be made; and it will be judged that the diodes in the network are connected correctly and reversely. , define the positive and negative poles for the diode, the power terminal is connected to the positive pole and the power supply terminal is connected to the negative pole to open the circuit; and to judge the connection relationship of the switch tube in the network, define the Vdd2 pin and Vdd3 pin as short circuit; extract the withstand voltage and capacitance of the capacitor in the effective path Capacitance: Parallel calculation of capacitance load, comparison of withstand voltage and power supply voltage and margin calculation, the automatic inspection method of the present invention is not easy to omit information, does not require complicated calculations, and can improve the reliability, stability and detection of the circuit precision.

The invention discloses a special sand magnetic adsorption method for a core-shooting sand core upper die, which is characterized by comprising the following steps: separating out the part of a sand core where special sand needs to be placed to manufacture a local sand core, placing the special sand on the local sand core, and embedding a steel plate in the local sand core; putting the local sandcore in an integral core box, and positioning the local sand core through a magnet; and manufacturing an integral sand core at one time, and combining the prefabricated local sand core into the integral sand core. The method has the creativity that the sand core part with the special sand (and cold iron) is manufactured into the local sand core, the magnet is arranged above the integral core box where the special sand needs to be placed, and the local sand core can be well positioned through the magnet, so the process is simple and easy to implement.

The invention relates to D-phase vanadium dioxide nano-star powder and a preparation method thereof. The powder is D-phase vanadium dioxide nano-star powder with a shape of pentagram or hexagram flat particles with the flat thickness of 30-60nm and the flat diameter of 60-100nm. Conical star point base thickness of the pentagram or hexagram particle is same with the flat thickness, conical star point base width is 30-60nm, and star point length is 70-100nm. The preparation method comprises the following steps: ammonium metavanadate is dissolved in deionized water, and the mixture is stirred, such that an ammonium metavanadate water solution is obtained; a formic acid solution is dropped into the ammonium metavanadate water solution being stirred, such that a mixed liquid with a pH value of 1-3 is obtained; the mixed liquid is set in a sealed state, and is allowed to react for 1-3d under a temperature of 180-220 DEG C, such that a reaction liquid is obtained; and the reaction liquid is sequentially subjected to solid-liquid separation, washing and drying, such that a target product is obtained. With subsequent heat treatment, obtained VO2(M) nano-star powder can be widely applied in the fields of intelligent temperature-control films, thermistor materials, photoelectric switch materials, infrared detection materials, gas sensors, storage materials, and the like.