Abstract: The present application relates to a bidirectional digital switching power amplifier based on a magnetic suspension drive platform and its multi-step current predictive control method. The control method includes the following steps: establishing a prediction model of a bidirectional digital switching power amplifier; introducing a feedback correction term for a closed loop prediction; calculating an optimal modulation duty cycle through a value function; generating, according to the obtained modulation duty cycle, four PWM drive signals by a pulse width modulation module to control four switch tubes respectively to achieve current prediction control. The present application effectively improves the system control accuracy with small steady-state error, small on-line computation amount, simple algorithm, easy digital realization, and good practical value and application prospect.

Abstract: According to an image processing method and system for improving three-dimensional display effect of blood vessels provided by the present invention, the image processing method comprises the following steps: design an interpolation algorithm to preprocess the original data to obtain a preprocessed image based on the original image volume data before projection; determine the blood vessel trend according to the preprocessed image, eliminate isolated points, and perform image smoothing processing on the blood vessel trend to obtain a smooth image; and process the smooth image by a nonlinear change method to perform nonlinear enhanced display of blood vessels and suppress the background. And improve the display effect of blood vessel signals.

Abstract: A permanent magnet motor with a high-efficiency air-water mixed cooling system is provided. An inner circumference of a stator core of the permanent magnet motor is provided with multiple stator slots along a circumferential direction, armature windings are arranged in the stator slots, an outer circumference of the stator core is provided with multiple axial ventilation channels along an axial direction and a radial ventilation channel along a radial direction. The radial ventilation channel is communicated with the axial ventilation channels and contacts with a rotor core. Stator water-cooling discs are arranged at both ends of the stator core. A casing is provided with an air inlet communicated with the radial ventilation channel, multiple air outlets communicated with the axial ventilation channels, casing water-cooled water inlets and casing water-cooled water outlets. The casing water-cooled water inlets and the casing water-cooled water outlets are both communicated with the stator water-cooling discs.

Abstract: A wire harness wall-passing structure and an installation method thereof. The wire harness wall-passing structure comprises: a sleeve pipe, a pouring sealant, and at least one sealing plug, wherein the sleeve pipe is alternately filled with the pouring sealant and the sealing plug along the axis direction of the sleeve pipe; and at least one first through hole formed in the sealing plug, and a wire harness which can penetrate through the pouring sealant and the first through hole in the sealing plug. According to the wire harness wall-passing structure, the sleeve pipe is filled with the pouring sealant and the sealing plug, so multi-stage sealing and multi-time sealing of the wire harness are achieved, the sealing performance of the wall-passing structure is greatly improved, and the wire harness wall-passing structure is more suitable for to-be-fixed devices such as a high pressure vessel.

Abstract: A tensegrity offshore wind power generation support structure is provided, relating to the technical field of offshore wind power. The support structure includes inclined columns, prestressed cables, a rigid support, a floating foundation and anchoring systems. A stable self-balancing space supporting structure is formed by the inclined columns and the cables; the inclined columns inclines outwards, upper parts of the inclined columns are connected with the prestressed cables; the bottom ends of the inclined columns are connected with the floating foundation; the middle parts of the inclined columns are connected with the rigid support; and the floating foundation is fixed with a seabed through the anchoring systems. According to the support structure, a tower in the traditional design is not needed, and all the cables are ensured to be in a tension state through the support of the inclined columns.

Abstract: A stator liquid cooling structure and a stator structure of a stator yokeless disc motor are provided. The cooling structure includes an annular stator bracket and a water jacket. An outer periphery of the stator bracket is in a groove structure and is fixedly connected with the water jacket. Opposite upper and lower ends of the water jacket are provided with a liquid inlet and a liquid outlet. The stator structure includes stator cores, an armature winding, the stator bracket and the water jacket. A first stator core and a second stator core of the stator cores are same in structure and oppositely arranged. The armature winding is wound on first stator tooth bodies and second stator tooth bodies of the stator cores; the first stator tooth bodies and the second stator tooth bodies are inserted into gaps between adjacent blade-shaped cavities and fixed on the stator bracket.

Abstract: A multi-stage gas atomization preparation method of titanium alloy spherical powder for a 3D printing technology includes the following steps: bar preparation and machining step, multi-stage gas atomization powder preparation step through vacuum induction, and powder screening step. The collision probability of the metal droplets at the gas atomization stage is reduced by controlling the gas atomization pressure and the feeding speed of the titanium alloy electrode bar in a hierarchical manner, so that the collaborative control of the particle size and the surface quality of the titanium alloy 3D printing powder in the gas atomization preparation process is realized.

Abstract: The present application belongs to the technical field of bridge engineering, and particularly relates to a structure for relieving cracking of a steel bridge deck. The structure for relieving cracking of a steel bridge deck comprises a steel bridge deck and a plurality of U-ribs welded and fixed to a bottom of the steel bridge deck, and further inventions an iron-based shape memory alloy (Fe-SMA) fixing unit, a filling unit, a structural layer, and a test wire. A Fe-SMA having a restoration capability in the case of heating is used and formed into a honeycomb structure to greatly reduce an amplitude of fatigue stress and an influence of fatigue cracking of a welding part on the bridge deck.

Abstract: The present invention relates to the technical field of bridges, and specifically discloses a bridge sling based on electrochemical detection on steel wire corrosion. By means of winding a steel wire bundle with a wrapping tape, and coating the wrapping tape with a shielding coating, the steel wire bundle and the shielding coating are electrically connected with positive and negative electrodes of a voltage test assembly respectively, so that simple and accurate detection on corrosion in the sling during service is realized, and the safety of the sling during the service is ensured.

Abstract: The present invention provides a high-pressure bearable scale type bridge rubber bearing, comprising spring rubber vibration reduction pad assemblies, a flexible steel plate assembly and a rubber bearing body. The rubber bearing body comprises an outer rubber portion and an inner rubber portion; the outer rubber portion is wrapped around the outside of the spring rubber vibration reduction pad assemblies and the flexible steel plate assembly; the spring rubber vibration reduction pad assemblies are arranged on the upper side and the lower side of the inner rubber portion; and the flexible steel plate assembly is fixedly mounted between the spring rubber vibration reduction pad assemblies. The rubber bearing of the present invention has a relatively large elastic deformation after being loaded and can effectively conduct vibration reduction and earthquake resistance during use.

Abstract: A method for quickly predicting a fatigue life of a wrinkle defect-containing main spar in a wind turbine blade is provided. The method includes: S1: testing a tensile property of a wrinkle defect-containing main spar to be tested; S2: calculating, according to surface temperature data of the specimen obtained in step S1, intrinsic dissipated energy of the main spar specimen under different loading stresses; S3: plotting a relational graph between intrinsic dissipated energy of the specimen and a corresponding ultimate tensile strength (UTS) level; S4: establishing, based on a change of the intrinsic dissipated energy in a fatigue process, a normalized residual stiffness model containing parameters to be determined, and putting fatigue test data into the model; S5: deducing a fatigue life prediction model for the wrinkle defect-containing main spar specimen according to the normalized residual stiffness model with determined parameters; and S6: obtaining a normalized failure stiffness.

Abstract: The invention relates to the technical field of operation and maintenance of wind turbines, and is also applicable to non-destructive measurement of a depth of a defect of other resin-based composite materials. It is aimed at the problem that the depth of the defect cannot be determined by an intuitive infrared thermal image in the measurement of a depth of a defect of a large wind turbine blade. This method not only ensures accuracy of the measurement, but can also be widely applied.

Abstract: Provided are a double auxiliary resonant commutated pole three-phase soft-switching inverter circuit and a modulation method. The circuit includes a three-phase main inverter circuit and a three-phase double auxiliary resonant commutator circuit. An A-phase double auxiliary resonant commutator circuit, an A-phase main inverter circuit, a B-phase double auxiliary resonant commutator circuit, a B-phase main inverter circuit, a C-phase double auxiliary resonant commutator circuit and a C-phase main inverter circuit are connected in parallel in sequence and simultaneously connected with a DC power supply in parallel. The present invention can achieve the separation of the resonant current of the double auxiliary resonant commutator circuit from the load current at the moment of current commutation, thereby effectively reducing the current stress of the auxiliary switching tubes and the efficiency can be greatly increased particularly under light load condition.