Abstract: The present application provides a hot-work die steel and a preparation method thereof wherein the chemical constituents of the hot-work die steel in mass percentage are as follows: C: 0.20-0.32 wt %, Si: ?0.5 wt %, Mn: ?0.5 wt %, Cr: 1.5-2.8 wt %, Mo: 1.5-2.5 wt %, W: 0.5-1.2 wt %, Ni: 0.5-1.6 wt %, V: 0.15-0.7 wt %, Nb: 0.01-0.1 wt %, and a balance of iron, wherein an alloying degree is 5-7%; a tensile strength of the hot-work die steel at 700° C. is 560-700 MPa; a value of hardness of the hot-work die steel at room temperature is 32-38 HRC after holding at 700° C. for 3-5 h; and the hot-work die steel has an elongation of 14% to 16% at room temperature, a percentage reduction of area of 48% to 65%, and an impact toughness of 52-63 J at room temperature. The hot-work die steel of the present application has an excellent thermal stability as well as a good plasticity and a toughness at room temperature.

Abstract: A production apparatus and method for electric arc furnace steelmaking with a fully continuous ultra-short process are provided. A continuous adding, melting, smelting and continuous casting of a metal material are integrated, and a metallurgy process is completed in a flowing of a molten steel, to realize a continuous production of ingot blanks. The production apparatus includes four operation sites of an electric arc furnace for melting and primary refining, a sealed tapping chute for molten steel flowing, a refinement storage bed for molten-steel desulfurization and alloying and a conticaster for continuous casting A material flow, an energy flow and a time stream in the four operation sites are in a dynamic equilibrium. The production apparatus and method realize a molten-steel casting is started within 120 minutes after the metal material is started to be continuously added, and an uninterrupted continuous production is maintained for above 80 hours.

Abstract: A production apparatus and method for electric arc furnace steelmaking with a fully continuous ultra-short process are provided. A continuous adding, melting, smelting and continuous casting of a metal material are integrated, and a metallurgy process is completed in a flowing of a molten steel, to realize a continuous production of ingot blanks. The production apparatus includes four operation sites of an electric arc furnace for melting and primary refining, a sealed tapping chute for molten steel flowing, a refinement storage bed for molten-steel desulfurization and alloying and a conticaster for continuous casting A material flow, an energy flow and a time stream in the four operation sites are in a dynamic equilibrium. The production apparatus and method realize a molten-steel casting is started within 120 minutes after the metal material is started to be continuously added, and an uninterrupted continuous production is maintained for above 80 hours.

Abstract: Provided are a multi-functional stratigraphic structure model testing system and testing method. The system includes a test piece testing device platform that includes a watertight fan-shaped closed cavity, a fluid-solid coupling loading system, and an anti-arc reaction frame system. A coupling loading system region consist of hydraulic (liquid) loading and multi-directional solid-skeleton loading onto a pore or crack test piece, which can be independently operated or combined with each other's. The fan-shaped closed cavity is fixed through the anti-arc reaction frame system, and a fan-shaped center region is provided with an application region of underground working face. The other two flat fan sides are provided with application regions of physical and chemical improvement for surrounding rock.

Abstract: A channel estimation method of a steel penetration system is configured to reduce computational complexity and required memory. The method includes: reconstructing, at a receiving end, a channel estimation with a compressed-sensing sparse reconstruction algorithm according to a received pilot signal to obtain estimation values of a channel state response of the steel penetration system; and equalizing a received signal of the receiving end according to the estimation values of the channel state response to obtain an equalized signal.

Abstract: Provided are a multi-functional stratigraphic structure model testing system and testing method. The system includes a test piece testing device platform that includes a watertight fan-shaped closed cavity, a fluid-solid coupling loading system, and an anti-arc reaction frame system. A coupling loading system region consist of hydraulic (liquid) loading and multi-directional solid-skeleton loading onto a pore or crack test piece, which can be independently operated or combined with each other's. The fan-shaped closed cavity is fixed through the anti-arc reaction frame system, and a fan-shaped center region is provided with an application region of underground working face. The other two flat fan sides are provided with application regions of physical and chemical improvement for surrounding rock.

Abstract: A method for preparing an oxygen-free passivated titanium or titanium-alloy powder product by means of gas-solid fluidization is provided.

Abstract: A method for developing shale gas by tapered gradient pressure drop with multi-stage fractured horizontal well is provided and the method comprises: acquiring fracturing crack form parameters of the multi-stage fractured horizontal well and reservoir characteristic parameters of nearby formation; dividing the formation near the shale gas multi-stage fractured horizontal well into strongly transformed area, weakly transformed area and matrix area; establishing pressure difference-flow models of gas-phase and water phase of the three areas respectively, and coupling the models of the three areas to establish production equation of the multi-stage fractured horizontal well; according to the production equation of the multi-stage fractured horizontal well, performing numerical simulation with different combinations of production pressure differences in the three stages of the multi-stage fractured horizontal well; and selecting a combination of production pressure differences with the greatest economic benefit as

Abstract: A channel estimation method of a steel penetration system is configured to reduce computational complexity and required memory. The method includes: reconstructing, at a receiving end, a channel estimation with a compressed-sensing sparse reconstruction algorithm according to a received pilot signal to obtain estimation values of a channel state response of the steel penetration system; and equalizing a received signal of the receiving end according to the estimation values of the channel state response to obtain an equalized signal.

Abstract: A method based on fluidizing for modifying and preparing low-cost titanium powders for 3D printing includes: using hydrogenated-dehydrogenated irregularly-shaped titanium powders as the raw material, adding the titanium powders to a fluidized bed reactor, and introducing Ar or H2 at the flow rate of 0.5-1.5 L/min, heating the reactor to 300-700° C., and fluidizing for 5-90 min to modify the titanium powders. When filled with high-purity argon gas and heated at high temperature, the sharp edges and corners of irregularly-shaped titanium powders are ground collision of the particles due to the friction among powder particles.

Abstract: A plastic single-axis zero-expansion composite material and a preparation method thereof are provided, featuring incorporating an ?-Fe second phase into a matrix of R2Fe17-type intermetallic compound, in which R refers to a rare earth element with a low atomic content of 4%. The material has simple synthesis steps and can be easily implemented, and the phase interface formed by the eutectic reaction is more stable than the composite structures obtained by the traditional solid-phase sintering, thereby realizing the regulation of the thermal expansion, and significantly improving the mechanical properties.

Abstract: A multi-system, multi-parameter, integrated, comprehensive early warning method for a coal and rock dynamic disaster includes: obtaining monitoring data of a plurality of monitoring systems for the coal rock dynamic disaster, and extracting multivariate characteristic parameters capable of reflecting precursor information of the coal and rock dynamic disaster in each monitoring system based on the monitoring data; screening out a combination of characteristic parameters with a highest early warning effectiveness in each monitoring system and an optimal critical value of each characteristic parameter based on the multivariate characteristic parameters; calculating a comprehensive early warning index and an early warning effectiveness of each monitoring system; and calculating a multi-system comprehensive early warning result of the coal and rock dynamic disaster based on the comprehensive early warning index and the early warning effectiveness of each monitoring system.

Abstract: A method for determining the temperature-induced sag variation of the main cable and the tower-top horizontal displacement of suspension bridges takes the sag variation and the span variation of each span of the main cable as the unknown quantities. By using the horizontal tension equilibrium at the tower top, the geometric relationship between the shape and the length of the main cable, and the compatibility condition to be satisfied by the sum of spans of each span of the main cable, a linear system of equations is constructed. The linear system of equations is solved to obtain the temperature-induced sag variation of the main cable and the tower-top horizontal displacement of the suspension bridge. This method can be extended to the temperature deformation analysis of the other cable systems with any number of spans such as transmission lines, ropeways, and the like.

Abstract: A multi-degree-of-freedom automatic center-adjusting device, a hydraulic quick-coupling device, and rescue equipment are provided. The automatic center-adjusting device includes an active coupling valve set, a spring, and a dynamic adjustment swing rack. A first end of the dynamic adjustment swing rack is fixed to operation tools, and a second end of the dynamic adjustment swing rack is connected to the active coupling valve set through the spring. The dynamic adjustment swing rack includes a frame, a limit slot, and a spring limit cylinder, wherein the frame is used to support and fix the active coupling valve set, the limit slot is used to define a limit activity position of the active coupling valve set, and the spring limit cylinder is used to constrain the spring. The automatic center-adjusting device is used to solve technical problems of position errors and a center mismatch in a coupling process.

Abstract: A multi-degree-of-freedom automatic center-adjusting device, a hydraulic quick-coupling device, and rescue equipment are provided. The automatic center-adjusting device includes an active coupling valve set, a spring, and a dynamic adjustment swing rack. A first end of the dynamic adjustment swing rack is fixed to operation tools, and a second end of the dynamic adjustment swing rack is connected to the active coupling valve set through the spring. The dynamic adjustment swing rack includes a frame, a limit slot, and a spring limit cylinder, wherein the frame is used to support and fix the active coupling valve set, the limit slot is used to define a limit activity position of the active coupling valve set, and the spring limit cylinder is used to constrain the spring. The automatic center-adjusting device is used to solve technical problems of position errors and a center mismatch in a coupling process.

Abstract: A multi-system, multi-parameter, integrated, comprehensive early warning method for a coal and rock dynamic disaster includes: obtaining monitoring data of a plurality of monitoring systems for the coal rock dynamic disaster, and extracting multivariate characteristic parameters capable of reflecting precursor information of the coal and rock dynamic disaster in each monitoring system based on the monitoring data; screening out a combination of characteristic parameters with a highest early warning effectiveness in each monitoring system and an optimal critical value of each characteristic parameter based on the multivariate characteristic parameters; calculating a comprehensive early warning index and an early warning effectiveness of each monitoring system; and calculating a multi-system comprehensive early warning result of the coal and rock dynamic disaster based on the comprehensive early warning index and the early warning effectiveness of each monitoring system.

Abstract: A flight test system for a flapping-wing aerial vehicle includes a host computer platform, a measurement mechanism, and a wind tunnel. The measurement mechanism is configured to mount a to-be-tested flapping-wing aerial vehicle prototype. The measurement mechanism includes an Euler angle controller, a flow angle controller, and a tripod. The flow angle controller is mounted on the tripod. The Euler angle controller is in transmission connection with the flow angle controller. The flapping-wing aerial vehicle prototype is detachably connected to the Euler angle controller by using a first connecting member. The host computer platform is in communication connection with the measurement mechanism and the wind tunnel, and is configured to control a wind speed of the wind tunnel and display a flight status of the flapping-wing aerial vehicle prototype in real time during test.

Abstract: An efficient long-service-life blowing method include the steps of introducing vanadium extraction converter flue gas and decarburization converter flue gas into an oxygen combustor; obtaining first-purity CO2—N2 mixed gas through the vanadium extraction converter flue gas; obtaining second-purity CO2—N2 mixed gas through the decarburization converter flue gas; obtaining O2—CO2—N2 mixed gas through the decarburization converter flue gas; obtaining first-purity CO2 gas through the second-purity CO2—N2 mixed gas; and using the first-purity CO2—N2 mixed gas for bottom blowing of the vanadium extraction converter, using the second-purity CO2—N2 mixed gas as a carrier gas for blowing iron ore powder into the vanadium extraction converter, and using the O2—CO2—N2 mixed gas and the first-purity CO2 gas as a carrier gas for bottom blowing of the decarburization converter and bottom injecting of lime powder into the decarburization converter.

Abstract: A simulation method for flow field of multi-stage fracturing on horizontal well in tight oil reservoir is provided.

Abstract: The present invention provides a device and a method for measuring overburden of injected gas in cyclic gas injection development of condensate gas reservoir. The device comprises sand packed model and temperature control system. The temperature control system is nested outside the sand packed model. The sand packed model comprises sand pack cell, four gas inlets, four gas outlets, bracket, direction control component, rotating shaft, upper cover, lower cover, fixing bolts, two top pressuring inlets, pressure transmission rods, pressure transfer piston and multiple gas sampling ports. The sand pack cell can be filled with quartz sand of different particle size and composition, and the angle of the whole device is adjusted by the direction control component.