Abstract: A full-hole reverse circulation cluster-type down-the-hole (DTH) hammer with multiple independent channels is provided. The DTH hammer includes a drill rod, a drill rod joint, a drill rod air pipe, a diversion chamber, at least one hammer, and an upper pressure plate, a lower pressure plate, and an upper outer hammer protection pipe for fixing the hammer, where at least one jet air pipe communicated with the diversion chamber and at least one drill cuttings discharge pipe are arranged between the hammers; lower ends of the jet air pipe and the drill cuttings discharge pipe are located close to a hammer drill bit; and the lower end of the jet air pipe is provided with jet holes for producing a negative pressure.

Abstract: This application provides a bulk acoustic wave resonator and a bulk acoustic wave filter, and relates to the technical field of filters. The bulk acoustic wave resonator includes a substrate, and a bottom electrode, a piezoelectric layer, a top electrode which are sequentially stacked on the substrate, and an outline of an orthographic projection of the top electrode on the substrate is formed by four curves which are end-to-end connected. Arc transition is set at a joint of every two adjacent curves, and every two curves arranged in a spaced manner are not parallel. Accordingly, reliability of devices can be effectively improved, meanwhile, parasitic resonance amplitude can be effectively restrained, a Q value is increased, and thus device properties are improved.

Abstract: A to-be-measured partially coherent fractional vortex beam passes through a scattering object, an error between measurable information and to-be-measured information is minimized by using an optimization algorithm, and a main electric field mode and a weight of a to-be-measured fractional vortex beam are reconstructed by using a multimode stacked diffraction algorithm. A cross-spectral density function of the partially coherent fractional vortex beam is calculated, a cross-spectral density of a partially coherent fractional vortex optical field is reconstructed, and complete information including light intensity, a light intensity association, an electric field association, a phase, and the like of the partially coherent fractional vortex optical field is obtained.

Abstract: The present disclosure relates to a method of preparing a nano-porous powder material. The method includes: firstly removing A in the alloy AxTy by using an ultrasonically-assisted de-alloying method to prepare a nano-porous T coarse powder, and then, allowing the nano-porous T coarse powder to perform M-ization reaction with a gas reactant containing M to obtain a nano-porous T-M coarse powder, and finally, further crushing the nano-porous T-M coarse powder using a jet mill to obtain a nano-porous T-M fine powder. The method can achieve low-cost mass production of the nano-porous T-M fine powder, bringing broad application prospects.