Abstract: Disclosed are a high-temperature superconducting suspension type wireless power transmission device and an assembly method thereof. The device comprises an alternating current power supply, wherein the alternating current power supply is electrically connected with a transmitting coil, and the transmitting coil is made of high-temperature superconducting materials; a suspended matter is mounted above the transmitting coil, the suspended matter is electrically connected with a receiving coil corresponding to the transmitting coil, and a plurality of permanent magnets fixedly connected with the suspended matter are uniformly mounted along the periphery of the receiving coil; and the transmitting coil is located in a low-temperature container to maintain a superconducting state. In combination with the superconducting magnetic suspension technology and the superconducting wireless charging technology, power is stored without the need of a complex energy storage device.

Abstract: A method for jointly estimating gain-phase error and direction of arrival (DOA) based on an unmanned aerial vehicle (UAV) array includes: equipping each UAV with an antenna, and forming a receive array through a swarm of multiple UAVs to receive source signals; when an observation baseline of the swarm remains unchanged, changing array manifold through movement of the UAVs, and re-sensing the source signals; for each sensed source signals, calculating a covariance matrix, and obtaining a corresponding noise subspace through eigenvalue decomposition; and constructing a quadratic optimization problem based on the noise subspace and array steering vector, constructing a cost function, and implementing joint estimation of the gain-phase error and the DOA through spectrum peak search. The method can jointly estimate the DOA and gain-phase error and calibrate the gain-phase error, thereby improving accuracy of passive positioning.

Abstract: A method for jointly estimating gain-phase error and direction of arrival (DOA) based on an unmanned aerial vehicle (UAV) array includes: equipping each UAV with an antenna, and forming a receive array through a swarm of multiple UAVs to receive source signals; when an observation baseline of the swarm remains unchanged, changing array manifold through movement of the UAVs, and re-sensing the source signals; for each sensed source signals, calculating a covariance matrix, and obtaining a corresponding noise subspace through eigenvalue decomposition; and constructing a quadratic optimization problem based on the noise subspace and array steering vector, constructing a cost function, and implementing joint estimation of the gain-phase error and the DOA through spectrum peak search. The method can jointly estimate the DOA and gain-phase error and calibrate the gain-phase error, thereby improving accuracy of passive positioning.

Abstract: A power conversion system includes a first controller, a system output end, at least one system input end, at least one power conversion component, and a bus communication apparatus coupled between each power conversion component and the first controller. Each system input end is in a one-to-one correspondence with each power conversion component. Each power conversion component is configured to convert an alternating current input through a first input end of each power conversion component into a direct current, and output the direct current through an output end of each power conversion component.

Abstract: A cooling system and a cooling method thereof. The system includes a first refrigeration device, a second refrigeration device, and a cold storage device. Both of the first refrigeration device and the cold storage device are configured to provide a first medium for an end device to supply cold to the end device, and the second refrigeration device is configured to provide a first medium for the cold storage device to perform cold charging on the cold storage device. A cooling side medium input port of the second refrigeration device is configured to receive a first medium output by the end device. A chilled side medium input port of the first refrigeration device is connected to a cooling side medium output port of the second refrigeration device and is configured to receive the first medium output from the cooling side medium output port of the second refrigeration device.

Abstract: The present invention provides a radar target detection method based on estimation before detection (EBD), which comprises: obtaining pre-detect targets (PDTs) based on conventional pulse-Doppler processing and pre-detection; estimating ranges and speeds of PDTs, i.e., performing parameter EBD; establishing a dimension-reduction observation model of a received signal based on PDTs and parameter thereof; reconstructing a target vector in the dimension-reduction observation model based on a sparse recovery algorithm; and designing a generalized likelihood ratio detector based on the reconstruction result for target detection. The method of the present invention can significantly reduce the radar signal processing loss, and the target detector used in the method has the constant false alarm rate (CFAR) property, so that the weak target detection performance can be greatly improved.

Abstract: Embodiments of this application provide an alternating current power supply circuit, a control method for an alternating current power supply circuit. The alternating current power supply circuit includes a rectifier module and an inverter module. The rectifier module includes a first inductor L1, a first branch, a second branch, a third branch, a first capacitor, and a second capacitor, the third branch includes a soft switching cell, the soft switching cell includes a first switching component and a second switching component that are reversely connected in series, and the first branch, the second branch, and the third branch form an I-type three-level topology or a T-type three-level topology. The inverter module includes a second inductor L1, a fourth branch, a fifth branch, a sixth branch, the first capacitor, and the second capacitor, the sixth branch includes the soft switching cell, and the fourth branch, the fifth branch.

Abstract: This application provides a voltage sampler and a solid-state transformer. The voltage sampler includes a conductive housing, at least one sampling board located inside the housing, and a conducting layer. Each sampling board includes at least two resistors and a voltage input end. The resistors in the sampling board are electrically connected in sequence in the direction from a first end to a second end. The resistor at the first end is electrically connected to the voltage input end. The resistor at the second end is electrically connected to the housing, and the housing is electrically connected to a fixed potential end. The conducting layer is disposed between the at least one sampling board and the housing in the voltage sampler. The conducting layer is electrically connected to a resistor in the sampling board.

Abstract: This application discloses a power electronic transformer wherein each phase includes a plurality of power conversion modules. Each power conversion module includes a rectifier AC/DC circuit, a direct current bus capacitor, and a direct current-direct current DC/DC circuit. In each power conversion module, an output end of the AC/DC circuit is connected to an input end of the DC/DC circuit; the direct current bus capacitor is connected in parallel to the output end of the AC/DC circuit; and input ends of all the AC/DC circuits are connected in series, and output ends of all the DC/DC circuits are connected in parallel. The power electronic transformer includes a relatively small quantity of power conversion modules, thereby reducing occupied space and costs.

Abstract: A method and a system for detecting a logic level of a rotor of a motor, and a motor are disclosed. The method comprises: obtaining an analog voltage output by a position sensor for a winding of the motor; setting a first commutation voltage and a second commutation voltage; generating a logic level according to the analog voltage, the first commutation voltage and the second commutation voltage; and performing angle correction on the logic level according to a first angle corresponding to the first commutation voltage and a second angle corresponding to the second commutation voltage. The first commutation voltage is a commutation voltage for triggering a rising edge, and the second commutation voltage is a commutation voltage for triggering a falling edge. This method may accurately identify the logic level corresponding to the motor rotor, improve uniformity of a commutation voltage and prevent fluctuations in motor speed.

Abstract: This application provides a dry-type transformer and a winding method thereof. The dry-type transformer includes a magnetic core, a first coil, a second coil, and a shielding component. The first coil is disposed around the exterior of the magnetic core, and the second coil is disposed around the exterior of the first coil. In a direction from the iron core to the second coil, the shielding component includes a first conducting layer, a second conducting layer, a third conducting layer, and a fourth conducting layer that are sequentially disposed at intervals, the first coil is disposed between the magnetic core and the first conducting layer, and the second coil is disposed between the second conducting layer and the third conducting layer.

Abstract: The present application discloses a method for early warning brandish of a transmission wire based on an improved Bayes-Adaboost algorithm, including: forming a classifier by training a historical brandish fault training set, and by using an Adaboost ensemble learning method, and obtaining an early warning result of the brandish of the transmission wire via the classifier according to real-time forecast meteorological information and information of different parameters of the transmission wire. The present invention can realize calculation and processing of forecast information of meteorological characteristic factors of the brandish of the transmission wire, structural parameters of the transmission wire and other related data, and obtain an early warning analysis result of a brandish disaster of the transmission wire in a region.

Abstract: This application provides a power supply method for a data center. The data center includes a first device and at least one second device, an importance of a first service in the first device is higher than an importance of a second service in the at least one second device, and the second service in the at least one second device is transferable. A power supply apparatus includes a first uninterruptible power supply UPS and a second UPS, the first UPS is configured to control a first power source and a first energy storage apparatus to supply power to the first device, and the second UPS is configured to control the first power source and a second energy storage apparatus to supply power to the at least one second device.

Abstract: Embodiments of this application disclose a power supply apparatus, a power supply system, and a data center designed to reduce the number of power conversion steps, equipment costs, and circuit loss. The power supply apparatus includes: a solid-state transformer configured to convert an alternating current into a first direct current; a first direct current/direct current converter, coupled to the solid-state transformer and configured to convert the first direct current into a second direct current; an energy storage component, coupled to the first direct current/direct current converter and configured to perform energy storage on the second direct current; and a second direct current/direct current converter, coupled to the first direct current/direct current converter and configured to convert the second direct current into a third direct current, where the third direct current is used to supply power to a load.

Abstract: A piezoelectric printhead includes a piezoelectric printing device, a manifold, a U-shaped flexible printed wiring element and an interconnection element. The piezoelectric printing device includes a piezoelectric plate and a substrate with at least one row of drop ejectors; first and second ink inlet ports; signal lines leading to corresponding signal input pads; and ground traces leading to at least one ground return pad. The manifold is fluidically connected to the ink inlet ports. The flexible printed wiring element includes a device connection region and a pair of legs that extend from the device connection region. The pair of legs includes signal connection lines and at least one ground connection line. The interconnection element is disposed between the device connection region of the flexible printing wiring element and a contact layer of the piezoelectric printing device that includes the signal input pads and the at least one ground return pad.

Abstract: An integrated boron removal and flocculation process for treating fracturing wastewater is disclosed. The process comprises: adjusting the pH of the fracturing flowback liquid to be treated to become alkaline and adding thereto an oxidant to carry out a reaction for a certain time period, so that the state of the boron present in the liquid is changed; and then adding a barium salt to the resulting reaction mixture to carry out a further reaction between the barium salt and the boron in the changed state to produce a precipitate. The stability of the flowback liquid is deteriorated by the addition of the oxidant. Suspended solids in the flowback liquid can be removed through adsorption, wrapping, and then settling by the action of the precipitate (a barium salt). The process integrates boron removal and flocculation and enables a boron removal rate of 80% or greater. The contents of the suspended solids and oil present in the fracturing flowback liquid after filtration each can be lowered to less than 5.

Abstract: Embodiments of this application provide a power conversion circuit. The power conversion circuit includes at least one first power conversion unit connected in series to a first phase line, at least one second power conversion unit connected in series to a second phase line, at least one third power conversion unit connected in series to a third phase line, a plurality of first start circuits connected in series to the first phase line, and a plurality of second start circuits connected in series to the second phase line. Each first start circuit includes a first relay and a first resistor that are connected in parallel, and first relays in all the first start circuits are sequentially closed after the power conversion circuit is powered on, to start the power conversion circuit. Each second start circuit includes a second relay and a second resistor that are connected in parallel.

Abstract: A control method for performing a multi-table join operation and a corresponding apparatus are disclosed. Fields in a table whose fields participating in a theta join operation and used in the query statement meet a first preset condition are decomposed, to obtain a plurality of first field groups, so that the theta join operation can be implemented in steps in a form of the plurality of field groups. This can reduce a data amount of Cartesian product calculation during one join operation, greatly reduce network transmission overheads, computing overheads, and memory overheads, and improve execution efficiency.

Abstract: A piezoelectric printing device includes a piezoelectric plate and a substrate with at least one row of drop ejectors. Each drop ejector includes a pressure chamber on a first side of the substrate and a nozzle on a second side of the substrate. The piezoelectric plate is attached to the substrate by a bonding layer. A first electrode layer is disposed on a first surface of the piezoelectric plate that is proximate to the first side of the substrate. The first electrode layer includes signal lines and ground traces corresponding to each pressure chamber. A second electrode layer including signal input pads and ground return pads is disposed on the first side of the substrate. Signal lines and ground traces in the first electrode layer are electrically connected to signal input pads and ground return pad(s) respectively on the second electrode layer through solder joints.

Abstract: A piezoelectric printing device includes a substrate and a piezoelectric plate. At least one row of drop ejectors is disposed along a row direction. Each drop ejector includes a nozzle in fluid communication with a pressure chamber that is bounded by side walls. The piezoelectric plate has a first surface that is disposed proximate to the first side of the substrate. A bonding layer is disposed between the piezoelectric plate and the substrate. An electrode layer is disposed between the first surface of the piezoelectric plate and the bonding layer. The electrode layer includes a signal line corresponding to each pressure chamber. Each signal line leads to a signal input pad. The electrode layer also includes ground traces disposed on both sides of each pressure chamber. The ground traces are electrically connected to at least one common ground bus that is electrically connected to at least one ground return pad.