Abstract: A liquid chromatography piston includes a connecting plate, below which two chromatographic columns are fixed, two pistons respectively slidably disposed within the two chromatographic columns and located above the stationary phase packing, two nuts rotatably disposed on the connecting plate and respectively in threaded connection with the two threaded tubes, rotating each nut allows adjustment of a position of one piston within one chromatographic column, two connecting strips, and two liquid inlet tubes respectively slidably arranged within the two threaded tubes, upper ends of the two liquid inlet tubes respectively pass through the two connecting strips and are fixedly connected to one flow guide fixed above the connecting plate, a sample tube and a cleaning agent tube are provided above the flow guide, the sample tube is configured to introduce a mobile phase sample, and the cleaning agent tube is configured to introduce a cleaning agent.

Abstract: A method for establishing a multi-degree-of-freedom bending-shear coupling nonlinear analysis model and a method for applying the model are provided. Collected building information is counted and analyzed; floor mass and floor moment of inertia of the building are calibrated by a mass and moment of inertia matrix; based on different types of the building structures, a proportion of the bending stiffness and a proportion of the shear stiffness of each floor of the building are different; global damping of the building is calibrated by a global damping matrix based on the processed building information; the global elastic rigidness of the building is calibrated by a global elastic rigidness matrix; a weight of the shear stiffness matrix and a weight of the bending stiffness matrix in the global elastic stiffness matrix are controlled; and a multi-degree-of-freedom bending-shear coupling model is established.

Abstract: Disclosed is a sheep PDGFD, nucleic acids encoding PDGFD and recombinant lentivirus, host cell and use thereof, which relate to the technical field of molecular cell biology. The sheep platelet-derived growth factor PDGFD includes one or two of PDGFD-T1 and PDGFD-T2. The amino acid sequence of PDGFD-T1 is set forth in SEQ ID NO:1, and the amino acid sequence of PDGFD-T2 is set forth in SEQ ID NO:2. PDGFD-T1 and PDGFD-T2 are able to significantly inhibit the differentiation and maturation of precursor adipocytes and significantly reduce the mRNA relative expression levels of adipogenic differentiation-related genes CEBP?, PPAR?, FAS, FABP4 and LPL, thereby inhibiting animal fat deposition and improving animal meat quality, and have important guiding significance in the fields of life science, medical science, animal husbandry and the like.

Abstract: The present disclosure provides a method for quantitatively evaluating overall damage of building structure based on structural strain energy, comprising: establishing an elastic-plastic calculation model, and preliminarily and secondarily screening seismic waves; applying seismic waves filtered at the second time to the elastic-plastic calculation model of the building structure for elasticity time history analysis, to acquire seismic waves; performing main shock and main aftershock bidirectional excitation on the elastic-plastic calculation model of the building structure by using the acquired seismic waves, and drawing an IDA curve; drawing basic calculation parameters, such as a graph of a family of IDA curves, percentile graphs, a building structure capacity curve and an energy versus time history graph under the action of the main shock and main after shock; calculating a structural strain energy-based building structure overall damage index by formulas, and performing quantitative evaluation on the bui

Abstract: A method for detecting a stress state-of rocks surrounding a roadway based on three-dimensional electric potential response is disclosed. By collecting electric potential data, and performing spatial interpolation on all the electric potential measurement points to obtain a three-dimensional electric potential imaging volume, three-dimensional electric potentials can be used to draw electric potential isosurface models. By using a radial basis function surface interpolation method to draw a three-dimensional abnormal electric potential inversion probability isosurface model, it is possible to intuitively visualize electric potential distribution spatial characteristics of rocks surrounding a roadway, so as to clearly display a spatial range, direction and development trend of abnormal stress zones, and accurately identify and determine the stress states of roadway rock formations.

Abstract: The present disclosure provides a method for detecting stress state of roadway surrounding rocks based on three-dimensional electric potential response.

Abstract: A fluidized coal mining method utilizing self-energy storage of a coal seam is provided, and includes developing a mine roadway, uncovering coal actively, mining coal in fluidization, and backfilling a goaf. Dynamic phenomenon is induced by uncovering the coal actively, a coal-mining drilling well is established from a ground to the coal seam, and the coal seam is subjected to hydraulic in-situ cutting, and a coal-rock mixture subjected to hydraulic cutting flows into a roadway system along a floor roadway, and then coal, gangue and water in the mixture are separated and recycled in a subsequent circulating coal mining process.

Abstract: A fluidized coal mining method utilizing self-energy storage of a coal seam is provided, and includes developing a mine roadway, uncovering coal actively, mining coal in fluidization, and backfilling a goaf. Dynamic phenomenon is induced by uncovering the coal actively, a coal-mining drilling well is established from a ground to the coal seam, and the coal seam is subjected to hydraulic in-situ cutting, and a coal-rock mixture subjected to hydraulic cutting flows into a roadway system along a floor roadway, and then coal, gangue and water in the mixture are separated and recycled in a subsequent circulating coal mining process.

Abstract: The present disclosure relates to the field of air conditioning technology. In particular, it involves a heat pump system and control method.

Abstract: Disclosed is a sheep PDGFD, nucleic acids encoding PDGFD and recombinant lentivirus, host cell and use thereof, which relate to the technical field of molecular cell biology. The sheep platelet-derived growth factor PDGFD includes one or two of PDGFD-T1 and PDGFD-T2. The amino acid sequence of PDGFD-T1 is set forth in SEQ ID NO:1, and the amino acid sequence of PDGFD-T2 is set forth in SEQ ID NO:2. PDGFD-T1 and PDGFD-T2 are able to significantly inhibit the differentiation and maturation of precursor adipocytes and significantly reduce the mRNA relative expression levels of adipogenic differentiation-related genes CEBP?, PPAR?, FAS, FABP4 and LPL, thereby inhibiting animal fat deposition and improving animal meat quality, and have important guiding significance in the fields of life science, medical science, animal husbandry and the like.

Abstract: The present disclosure relates to the field of air conditioning technology. In particular, it involves an air control method for air handler unit.

Abstract: A LiDAR odometry method based on the directed geometric point and sparse frame includes: obtaining original three-dimensional point cloud data of a surrounding environment in the coordinate system of the current frame of the LiDAR sensor; constructing and converting the first directed geometric point set and first environmental directed geometric point set into the second directed geometric point set and second environmental directed geometric point set in the world coordinate system, respectively; calculating candidate associated points in the second environmental directed geometric point set in association with each point in the second directed geometric point set, and determining the best associated point of each point in the second directed geometric point set; constructing and solving a pose optimization function to obtain an optimized pose from the coordinate system of the current frame of the LiDAR sensor to the world coordinate system; and updating directed geometric point sets of sparse frames.

Abstract: The present disclosure relates to the field of air conditioning technology. In particular, it involves a heat pump system and control method.

Abstract: Disclosed are a measurement-while-drilling method and device for obtaining a coal seam gas parameter applicable to measurement of a coal seam gas/coal seam methane parameter while drilling and evaluation of gas drainage performance. The invention performs a measurement-while-drilling operation to obtain information about downhole gas and a coal seam, thereby realizing on-site measurement of a coal seam gas parameter while drilling. The measurement-while-drilling device for obtaining a coal seam gas parameter comprises a compartment (17), a pressure sensor (15), a temperature sensor (14), a flow sensor (4), an acoustic emission sensor (16), a monitoring and control module (11), a power module and a communication module. The device is installed between a drill bit (1) and a first drill pipe (20).

Abstract: The present invention provides an inversion calculation method of coal-bed gas parameters of fast test while-drilling. The technical solution is that an inversion calculation method of coal-bed gas parameters of fast test while-drilling includes: during drilling in a coal bed, testing a gas flow and a gas concentration of an orifice in real time while-drilling, calculating drilling gas discharge amounts of the orifice, inversely calculating a coal-bed gas pressure at a drill bit based on borehole and coal-bed permeability parameters, and calculating a coal-bed gas content according to a gas content and gas pressure relational expression. The present invention has the beneficial effects that the present invention does not occupy the drilling and drill rod replacement time, is accurate, convenient, real-time and fast, and can test and calculate the coal-bed gas parameters of each section along the whole borehole length.

Abstract: The present disclosure relates to the field of air conditioning technology. In particular, it involves a refrigerant charging method for variable speed compressor based ac system.

Abstract: The present disclosure relates to the field of air conditioning technology. In particular, it involves an air control method for air handler unit.

Abstract: The present invention provides an inversion calculation method of coal-bed gas parameters of fast test while-drilling. The technical solution is that an inversion calculation method of coal-bed gas parameters of fast test while-drilling includes: during drilling in a coal bed, testing a gas flow and a gas concentration of an orifice in real time while-drilling, calculating drilling gas discharge amounts of the orifice, inversely calculating a coal-bed gas pressure at a drill bit based on borehole and coal-bed permeability parameters, and calculating a coal-bed gas content according to a gas content and gas pressure relational expression. The present invention has the beneficial effects that the present invention does not occupy the drilling and drill rod replacement time, is accurate, convenient, real-time and fast, and can test and calculate the coal-bed gas parameters of each section along the whole borehole length.

Abstract: A measurement-while-drilling method and device assesses outburst risk and evaluates gas drainage performance of a coal seam. The device includes a compartment, a pressure sensor, a temperature sensor, a flow sensor, an electromagnetic sensor, an acoustic sensor, a wave velocity measurement module, a monitoring and control module, a power supply and a communication interface. These are installed between a drill bit and an inclinometer or a first drill pipe. Measurements are performed while drilling to obtain a real time gas parameter, lithologic and coal seam information, for on-site assessment of outburst risk. During drill bit replacement, gas pressure, temperature, flow velocity, wave velocity, electromagnetic radiation, and an acoustic signal are recorded in real time, to calculate stress of the coal seam and coal seam outburst risk. On-site measurement is done while drilling without sampling and can use multiple parameters to perform synchronous measurement to obtain a comprehensive evaluation.

Abstract: A measurement-while-drilling method and device assesses outburst risk and evaluates gas drainage performance of a coal seam. The device includes a compartment, a pressure sensor, a temperature sensor, a flow sensor, an electromagnetic sensor, an acoustic sensor, a wave velocity measurement module, a monitoring and control module, a power supply and a communication interface. These are installed between a drill bit and an inclinometer or a first drill pipe. Measurements are performed while drilling to obtain a real time gas parameter, lithologic and coal seam information, for on-site assessment of outburst risk. During drill bit replacement, gas pressure, temperature, flow velocity, wave velocity, electromagnetic radiation, and an acoustic signal are recorded in real time, to calculate stress of the coal seam and coal seam outburst risk. On-site measurement is done while drilling without sampling and can use multiple parameters to perform synchronous measurement to obtain a comprehensive evaluation.