Abstract: Disclosed in the present invention is a voltage and current control method for a direct-current transmission system. The method comprises: calculating a DC voltage reference value of a voltage source converter of a DC voltage control end, on the basis whether a direct-current voltage end of a direct-current pole of a direct-current transmission system substantially controls a direct-current voltage; using ½ of the calculated direct-current voltage reference value of the voltage source converter as a bridge arm voltage direct-current bias, calculating a difference between the direct-current voltage reference value of the voltage source converter and a measured direct-current voltage value, and inputting the difference into a direct-current voltage control outer loop of the voltage source converter to perform closed-loop control, so as to control the direct-current voltage or the direct current of the direct-current pole.

Abstract: Disclosed is a noise reduction device for heat dissipation fans, the noise reduction device being applied to a heat dissipation fan with an interference structure for rotor and stator blades, wherein the noise reduction device comprises a duct formed at an end portion of a through-flow area of the heat dissipation fan, the inner diameter D of the duct is determined by the size and the rotation speed of the heat dissipation fan, and the axial length L of the duct is determined by an acoustic cutoff condition of the heat dissipation fan.

Abstract: The present invention provides a series compensator and a control method. The series compensator includes a series transformer, a series transformer bypass device, a voltage source converter, a high-speed converter bypass device, a high-speed switch, and a reactor. The reactor and the high-speed switch are connected in parallel to form a current limiting module; one winding of the series transformer has two ends connected in series to a line, and the other winding thereof is sequentially connected to the current limiting module and the high-speed converter bypass device; the voltage source converter and the high-speed converter bypass device are connected in parallel; and at least one winding of the series transformer are connected in parallel to at least one series transformer bypass device.

Abstract: An intraoperative near-infrared-I and near-infrared-II multi-spectral fluorescent navigation system and method of using same includes a light source module for emitting white light and excitation light for illuminating tissue to be tested to generate an emission light. An optical information collection module includes a white light camera for collecting the white light image, and near infrared-I and near infrared-II fluorescence cameras for collecting the near infrared-I and near infrared-II fluorescence images. A central control module is coupled to the light source and the optical information collection modules. An image processing unit pre-processes the white light image, and the near infrared-I and near infrared-II fluorescence images, for de-noising and enhancement.

Abstract: A bipolar bidirectional DC converter comprises at least two valve group series (101, 102) and at least six magnetic elements (103), and said valve group series are divided into a Type-I valve group series (102) and a Type-II valve group series (101) each valve group series (101, 102) comprises a high-voltage DC port, a low-voltage DC port and at least three AC ports, and each AC port is connected to a magnetic element (103); and the other ends of the magnetic elements (103), which are connected to all the AC ports in the same valve group series (101, 102), are connected.

Abstract: The present disclosure provides a fine identification method of a tight reservoir fracture based on conventional logging data. The method includes: eliminating a logging interference factor from a non-fracture response, choosing a basic lithological background for fracture identification, analyzing logging response features on different fracture scales, analyzing fracture aperture and filling features on a scale that can be identified by conventional logging data, identifying occurrence of an open fracture, and identifying a development degree of a fracture through a relative amplitude difference between a deep resistivity and a bedrock resistivity. The method of the present disclosure is suited for fine evaluation of a tight reservoir fracture.

Abstract: A DC voltage coordination control method is applied to a multi-terminal VSC-HVDC power transmission system or a VSC-HVDC power grid system. When a lower-level control is used in the active power control mode, the active power reference value of the converter is generated according to the converter DC voltage and the converter DC voltage active power curve; it also includes an upper-level control to adjust the control mode and active power setting value of the lower-level control to ensure the steady-state performance of the system. This method has low dependence on communication, avoids the problem that the fixed slope and margin cannot meet all operating conditions, and is suitable for large-scale VSC-HVDC systems, and has scalability.

Abstract: Provided are exosomes sourced from a granulocyte myeloid-derived suppressor cell and an application thereof. The exosomes are named as G-MDSC exo. Also provided is a use of the exosomes in preparing a drug used for suppressing autoimmune diseases. The G-MDSC exo can effectively suppress proliferation of CD4+T cells in vitro, promote induced proliferation of T regulatory (Treg) cells, alleviate foot swelling of model mice having delayed-type hypersensitivity, and suppress attacks of inflammatory bowel disease (IBD) and collagen-induced arthritis (CIA) of the mice.

Abstract: A coordinated control method for series voltage source converter valve groups comprises: allocating a total direct-current voltage reference value or a total active power reference value at the end where a direct-current electrode series voltage source converter valve group is located according to the total number of voltage source converter valve groups in series; for a direct-current voltage control end, controlling the direct-current voltage of each valve group according to the assigned direct-current voltage reference value for each valve group; for an active power control end, controlling the active power of each valve group according to the assigned active power reference value for each valve group and based on adding the active power compensation amount of the valve group which has voltage equalization effects on the valve group. Correspondingly, also providing a coordinated control device for series voltage source converter valve groups.

Abstract: A unidirectional DC voltage conversion device comprises a front end circuit (2), a main power circuit (1), a preceding-stage auxiliary isolation switch (5), and a subsequent-stage auxiliary isolation switch (6). A preceding-stage port of the main power circuit (1) and a subsequent-stage port of the front end circuit (2) form a cascade connection. The preceding-stage auxiliary isolation switch (5) is connected to a negative terminal (8) of a preceding-stage port of the front end circuit (2), and forms, together with a positive terminal (7) of the preceding-stage port of the front end circuit (2), a first input port of the unidirectional DC voltage conversion device.

Abstract: A bipolar bidirectional DC converter comprises at least two valve group series (101, 102) and at least six magnetic elements (103), and said valve group series are divided into a Type-I valve group series (102) and a Type-II valve group series (101) each valve group series (101, 102) comprises a high-voltage DC port, a low-voltage DC port and at least three AC ports, and each AC port is connected to a magnetic element (103); and the other ends of the magnetic elements (103), which are connected to all the AC ports in the same valve group series (101, 102), are connected.

Abstract: A movable platform includes one or more propulsion units configured to provide a driving force to the movable platform and a control unit operatively coupled to the one or more propulsion units. The control unit is configured to: communicate with a plurality of batteries adapted to supply current to the one or more propulsion units; obtain one or more electrical characteristics of each of the plurality of batteries; and determine, based on the electrical characteristics, a controlling signal to set a power supply state for at least one of the plurality of batteries.

Abstract: A coordinated control method for series voltage source converter valve groups comprises: allocating a total direct-current voltage reference value or a total active power reference value at the end where a direct-current electrode series voltage source converter valve group is located according to the total number of voltage source converter valve groups in series; for a direct-current voltage control end, controlling the direct-current voltage of each valve group according to the assigned direct-current voltage reference value for each valve group; for an active power control end, controlling the active power of each valve group according to the assigned active power reference value for each valve group and based on adding the active power compensation amount of the valve group which has voltage equalization effects on the valve group. Correspondingly, also providing a coordinated control device for series voltage source converter valve groups.

Abstract: The invention discloses a method for strengthening and widening subgrade with geocell based on conductive polymer, which belongs to the technical field of road construction. It includes the following steps: slope cutting and bench excavation for the existing embankment slope; leveling for the treated existing subgrade; filling and widening subgrade on the basis of the leveled existing subgrade; compacting the widened subgrade so that the compacted widened subgrade and the leveled existing subgrade are in the same plane; on the widened Subgrade The geocell based on the conductive polymer is tensioned and fixed for the first time; the geocell based on the conductive polymer is compacted to obtain the widened Subgrade of the geocell based on the conductive polymer. It can minimize the possibility of longitudinal cracks between the existing subgrade and the widened subgrade.

Abstract: A method and apparatus for suppressing the impact of a compensator on line distance protection is provided, wherein the method comprises: obtaining a first current of a line connected to a compensator or series converters in the compensator, and a first voltage of a bus connected to the compensator or the line connected to the compensator; exiting the series converters and series transformers if the first current is greater than a preset current threshold and a duration is greater than a first preset time threshold; exiting the series converters and the series transformers if the first voltage is less than or equal to a preset voltage threshold and duration is greater than a second preset time threshold set the output voltage of the series converters to zero, and if a second current of an element corresponding to the first current meets conditions which the first current needs to meet; and otherwise, canceling the setting of the output voltage of the series converters to zero and obtaining a first current if

Abstract: The present disclosure provides a light-weight flexible high-thermal-conductivity nano-carbon composite film and a method for preparing same. The nano-carbon composite film includes a plurality of composite units laminated sequentially. The, composite unit includes flexible adhesive layers and a graphene film layer, and the flexible adhesive layers are disposed on both sides of the graphene film layer. The preparation method includes sequentially laminating the composite units and hot pressing to obtain the nano-carbon composite film. The nano-carbon composite film has the characteristics of high thermal conductivity, light weight and flexibility, and has an in-plane thermal conductivity of up to 500 W/m·K or higher, a density of 2.0 g/cm3 or less, and still a thermal conductivity of 500 W/m·K or higher after the nano-carbon composite film is repeatedly bent by 180° for 50 times while there is no peeling of graphene from the surface.

Abstract: A FFL-based magnetic particle imaging three-dimensional reconstruction method includes: acquiring current signal data of an induction coil during FFL-based three-dimensional scanning process of a scanned object; based on the current signal data, performing deconvolution through a preset kernel function to acquire a two-dimensional image data set, wherein the kernel function is a step function with L2 regularized constraint; based on the two-dimensional image data set, acquiring an initial three-dimensional image by using a Wiener filtering deconvolution algorithm; and based on the initial three-dimensional image, performing deconvolution through a Langevin function, and acquiring a final three-dimensional image by Radon transformation.

Abstract: A fault switch configuration and clearing method in a flexible DC converter station, the flexible DC converter station is configured with a grid side switch and a valve side phase-split switch in the converter station. When a fault occurs, a faulty phase and a non-faulty phase are detected and identified by means of differential protection or low voltage overcurrent. An alternating current zero crossing condition is created by means of firstly turn off the non-faulty phase valve side phase-split switch and the grid side switch, thereby cutting off the faulty phase, disconnecting the connection between a power supply and a fault point, and achieving the clearing for faults. The described fault-clearing method is simple and practical, highly reliable, and connection between the fault point and the power supply is quickly and effectively cut; converter station equipment is effectively protected, and further expansion of the fault is avoided.

Abstract: A FFL-based magnetic particle imaging three-dimensional reconstruction method includes: acquiring current signal data of an induction coil during FFL-based three-dimensional scanning process of a scanned object; based on the current signal data, performing deconvolution through a preset kernel function to acquire a two-dimensional image data set, wherein the kernel function is a step function with L2 regularized constraint; based on the two-dimensional image data set, acquiring an initial three-dimensional image by using a Wiener filtering deconvolution algorithm; and based on the initial three-dimensional image, performing deconvolution through a Langevin function, and acquiring a final three-dimensional image by Radon transformation.

Abstract: A second near-infrared window/first near-infrared window dual-mode fluorescence tomography system having a lighting module, an excitation module, a second near-infrared window collection module, a first near-infrared window collection module, a CT imaging module and a central control module. The central control module is configured to reconstruct second near-infrared window three-dimensional and tomographic images and first near-infrared window three-dimensional and tomographic images based on the white light images, the second near-infrared window fluorescent images, the first near-infrared window fluorescent images, and the CT images. The reconstructed three-dimensional space tumor signal has depth characteristics, which is closer to the real distribution of tumors, such that the reconstruction position is more accurate. The three-dimensional shape of the tumor is displayed intuitively and clearly at any angle with the usage of image display unit.