Abstract: A plant leaves-derived carbon material doped with two metals and preparation and use thereof are provided, the carbon material prepared by carbonizing, in an inert atmosphere, plant leaves which have absorbed ions of two metals M1 and M2. The metal M1 is Co, Mn, or Fe. The metal M2 is Ni, Cu, or Zn. The carbon material can be used as an efficient, green, and safe catalyst for the selective oxidation of cycloalkanes to produce cycloalkanols and cycloalkanones, and enable an increased selectivity of the target products (thus less by-products), a low yield of cycloalkyl peroxides, reduced reaction temperature, low environmental impact, and safe production.

Abstract: A drainage device, a water tank, a ventilation area design method thereof, and a storage medium and an electronic apparatus, wherein the top of the water tank is provided with a ventilation slit, an area of which is adjustable in real time, and the bottom of the water tank is provided with a drainage orifice. A determination model for determining whether bubbles are generated during a drainage process of the water tank is established, and a relationship between an area of the drainage orifice and that of the ventilation slit, which satisfies the condition of no bubble generation during the drainage process, is established on this basis.

Abstract: Disclosed in the present invention is a two-dimensional direction-of-arrival estimation method for a coprime surface array based on virtual domain tensor filling, which mainly solves the problems of the loss of multi-dimensional signal structural information and the inability to fully utilize virtual domain statistics in the existing method. The steps thereof are as follows: constructing a coprime surface array; modeling a tensor of a received signal of the coprime surface array; constructing an augmented non-continuous virtual surface array based on cross-correlation tensor transformation of the coprime surface array; deriving a virtual domain tensor based on mirror extension of the non-continuous virtual surface array; dispersing contiguous missing elements by reconstructing the virtual domain tensor; filling the virtual domain tensor based on the minimization of a tensor kernel norm; and decomposing a filled virtual domain tensor to obtain a direction-of-arrival estimation result.

Abstract: Disclosed are a high-speed motor system with air bearing support and a control method thereof. The system includes: a rotating shaft, air bearings, a motor stator, a motor rotor, and radial displacement sensors. The radial displacement sensors are arranged in two groups, located outside the rotating shaft at both sides of the motor rotor; the radial displacement sensors are used to detect displacement of the rotating shaft in x-axis and y-axis directions. The motor stator is provided with stator slots having armature windings inside. The armature windings are electrically connected to a controller. The armature windings are averagely divided into p winding units according to the number of pole pairs p thereof. The controller includes p controller units that control the winding units respectively. The controller unit inputs a damping current component to the corresponding winding unit, for generating an electromagnetic damping force.

Abstract: A method for a direct current (DC) islanding detection based on positive feedback of a bus voltage at a specific frequency, essentially including three steps: extraction of a specific frequency component of the bus voltage, injection of a disturbance component of the specific frequency, and determination of DC islanding. The extraction of the specific frequency component of the bus voltage and the injection of the disturbance component of the specific frequency constitute a positive feedback mechanism in a power management unit control loop. In a grid-connected mode of a DC grid, the positive feedback mechanism fails due to a control action of a voltage management unit on a bus, and the bus voltage remains stable. In an islanding mode of the DC grid, under an action of the positive feedback mechanism, the power management unit allows the bus voltage to generate a self-excited oscillation at the specific frequency.

Abstract: The present disclosure discloses an offshore wind farm low-frequency alternating-current uncontrolled rectification electric power transmission system, comprising an onshore converter station and an offshore alternating-current system. The offshore alternating-current system comprises wind turbine generators, alternating-current submarine cables, a confluence bus, and offshore booster stations; the onshore converter station comprises a wind field side alternating-current bus, an alternating-current system side alternating-current bus, an alternating-current filter, an energy dissipation device, a rectifier, and a converter; the rectifier is composed of a three-phase six-pulse uncontrolled rectifier bridge, and the converter may be an MMC or an LCC; the rated frequency of the offshore alternating-current system is selected to be close to 10 Hz.

Abstract: The present invention relates to a method for preparing a hollow covalent organic framework (COF) material and hollow COF material prepared by said method. Said method is characterized in including a monomer displacement step in the method, thereby obtaining the hollow COF material with a controllable particle size, wall thickness and/or specific surface area.

Abstract: The present invention relates to the technical field of organic light-emitting materials, and provides a tetradentate cyclometalated platinum (II) complex based on an oxygen atom linkage and containing phenyl acridine and an application thereof. The tetradentate cyclometalated platinum (II) complex has the structure as represented by general formula (I). (I) The cyclometalated platinum (II) complex in the present invention adopts a tetradentate ligand, is high in rigidity, and can improve the light stability of a light-emitting material. At the same time, the complex molecule can strongly emit light, and therefore can be used as a light-emitting material in an OLED device.

Abstract: A multi-nozzle concurrent printing system includes a plurality of extrusion type nozzle assemblies, a three-axial translation mechanism and an objective table. Each nozzle assembly is provided with a nozzle, a storage barrel and a temperature control module; the three-axial translation mechanism includes an X-axial translation unit, a Y-axial translation unit and a Z-axial translation unit, and the nozzle assemblies are mounted on the Z-axial translation unit; and there are a plurality of nozzle assemblies, the printing system is provided with a concurrent calibration sensor, and the concurrent calibration sensor is taken as an original point of a coordinate system of the printing system. The printing system is provided with the plurality of nozzle assemblies which can work cooperatively or sequentially, the printing mode is flexible and changeable, and non-uniform mixing system forming of materials can be realized; and stable output of the materials in a formal printing task is guaranteed.

Abstract: A dry dual-scroll vacuum pump includes a driving assembly and an upper cover located above the driving assembly, wherein the driving assembly includes an output shaft, and a movable disk is eccentrically arranged on the output shaft; two groups of first scroll teeth that are centrally symmetrical are arranged on a side of the movable disk that faces the upper cover; a fixed disk is arranged at a lower end of the upper cover, second scroll teeth that are in one-to-one correspondence with the first scroll teeth are arranged on the fixed disk, and the first scroll teeth are meshed with the second scroll teeth to form a compression cavity; and the upper cover is further provided with an air inlet and an air outlet, which correspond to the compression cavity.

Abstract: An experimental device and method for measuring a motion probability of nonuniform sediment are provided. The method includes: dyeing sediment of different particle sizes to obtain nonuniform dyed sediment, sticking sediment with the same grades to the bottom of a flume to form a rough plate; soaking the nonuniform dyed sediment, laying the nonuniform dyed sediment on the sediment feeder, transporting the sediment by water with given intensity, and once the flow is stable, starting the sediment feeder to perform a test until the sediment stops moving. Collecting, drying and sieving the sediment in the bedload collector and the suspended load collector, and weighing the dyed sediment of different particle sizes. Computing the incipient probability and the suspension probability respectively by measuring the weight ratios of the sediment of different grades from the two collectors to the initial ones.

Abstract: A transfer impedance calibration device for transducers based on spatial frequency domain smoothing technology is provided. The calibration device comprises a signal transmitter, a power amplifier, a transducer pair, a measurement amplifier, a signal collector, a measurement processor and a current sampler. The device extracts acoustic channel information through the sound filed spatial information or measurement method to design a spatial domain smoothing filter, and then comprehensively processes the transmitted current signal and the received signal through the spatial frequency domain smoothing technology to obtain the transfer impedance of the transducer pair.

Abstract: The present disclosure relates to a searchable encrypted data sharing method and system based on blockchain and homomorphic encryption, which protects security of sensitive data on the blockchain and realizes searchable and homomorphic calculation of data ciphertext. According to the present disclosure, a data owner encrypts the generated sensitive data and the keywords extracted according to the data with his own key, and then sends the encrypted transaction information to the cloud server. The cloud server verifies the identity of the data owner. If the verification succeeds, the uploaded ciphertext data is stored on a local server, and a ciphertext index, keyword ciphertext and related evidences of the data storage are uploaded to an alliance chain. The alliance chain node verifies the consistency of the uploaded transaction information, and if the verification succeeds, the transaction information is recorded.

Abstract: A phase frequency detector-based high-precision feedback frequency measurement apparatus and method: a Field Programmable Gate Array (FGPA) roughly measures a frequency fx of a measured time-frequency pulse by an equal-precision frequency measurement method; a Direct Digital Synthesizer (DDS) automatically synthesizes a frequency fx? according to the fx roughly measured by the FPGA; the fx and the fx? are sent to a phase frequency detector for performing phase frequency detection and then sent to the FPGA after passing through a charge pump, a low-pass filter circuit, and an (Analogue-to-Digital) A/D converter; the FPGA processes a frequency difference obtained by the phase frequency detector and then transmits the processed frequency difference to the DDS to form a negative feedback frequency measurement system so that the DDS continuously adjusts the fx? according to a frequency difference measurement result until the output of the DDS is stable.

Abstract: A sample to be measured is placed in a medium solution between two circular magnets to ensure that the sample to be measured is levitated in a set circular area between the two circular magnets, and a levitation position of the sample to be measured in the magnetic field is measured. The density of the sample is calculated according to formula (I): ? s = ? m + ? m - ? s g ? ? 0 ? ( B r ? ? B z ? r + B z ? ? B z ? z ) . Compared to the prior art, the method of the present disclosure provides a novel method for measuring a density of a substance, in which the involved device is easy to operate and has low cost, and the measurement results are easy to observe and have high accuracy.

Abstract: A patrol helmet and method for livestock and poultry farms is described herein. The patrol helmet is wirelessly connected to an online farm management system on a cloud platform. The patrol helmet includes a helmet body, a controller, an augmented reality (AR) display component, an infrared (IR) camera, and a visible light camera. The AR display component is secured at the bottom edge of the helmet body. Both the IR camera and the visible light camera are disposed on the helmet body. The IR camera, the visible light camera, and the AR display component each is electrically connected to the controller. The IR camera and the visible light camera are configured to photograph livestock or poultry in an area in front of a wearer to obtain a temperature and an image of the livestock or the poultry.

Abstract: Provided is a hemostatic composition comprising trypsin and zeolite, wherein pore channels of the zeolite are micropores, the zeolite contains divalent metal cations, and the mass ratio of the trypsin to the zeolite is 1:200-4:10. In the present invention, the trypsin specifically binds to the zeolite, allowing the trypsin to maintain a certain conformation on the surface of the zeolite and to obtain a higher procoagulant activity, thereby obtaining a hemostatic composition with an excellent blood coagulation effect. The hemostatic composition of the present invention has the advantages of a simple preparation method, low cost and convenient use, and can be widely used in hemostasis during trauma and operations, especially in emergent hemostasis in hemophilia patients.

Abstract: A high-efficiency and short-process method for preparing a high-strength and high-conductivity copper alloy is disclosed, comprising the following steps: performing horizontal continuous casting to obtain an as-cast primary billet of copper alloy, wherein the alloying elements in the obtained as-cast primary billet being in a supersaturated solid solution state; after peeling the obtained as-cast primary billet, directly performing continuous extrusion, cold working and aging annealing treatment to obtain a copper alloy, and keeping the alloying elements of the billet in a supersaturated solid solution state during the process of continuous extrusion. The method shortens the flow, reduces energy consumption and improves the product forming rate.

Abstract: A backup voltage and frequency support method for a 100%-renewable energy sending-end grid, including: (S1) selecting a plurality of support nodes in the 100%-renewable energy sending-end grid; (S2) mounting a backup voltage and frequency support device at each support node; and (S3) dynamically adjusting an active power output of a renewable energy station of the 100%-renewable energy sending-end grid according to a frequency of a grid-connection point.

Abstract: Related to is a bidirectional CLLC circuit with a coupled inductor, which is associated with a circuit topology and operation control of a bidirectional CLLC resonant converter. Provided is a structure of a bidirectional CLLC resonant circuit with a coupled inductor, including a primary side bridge, a secondary side bridge, a primary side resonant capacitor, a secondary side resonant capacitor, a coupled resonant inductor, and a transformer. Compared with a structure of a conventional bidirectional CLLC resonant circuit, two separate resonant inductors located at a primary side and a secondary side in an original resonant cavity are replaced with one coupled resonant inductor in the circuit; the coupled resonant inductor has opposite dotted terminals with the transformer, and a primary side and a secondary side of the coupled resonant inductor are respectively in serial connection with a primary side and a secondary side of the transformer.