An analysis and research on composite modulation algorithm
This paper focuses on the problem of Doppler spread caused by high-speed target motion during coherent accumulation period for linear FM signals, then a Dual linear FM composite algorithm is proposed. The theory analysis and simulation are presented, and the conventional processing algorithm is compared with the proposed algorithm based on the echoed signal. The results shows that the composite algorithm is useful and able to be realized in engineering.
Integration Detection Research for Moving Target with High Velocity Based on Changeable Pulse Width Waveform
This paper presents a new method of transmiting changeable pulse width signals to solve the problem of a high velocity target coherent integration at low signal-to-noise ratio with meter-wave low pulse repetition frequency radar.First,wide pulse echoes are used to estimate the moving parameters.Secondly,narrow pulse echoes are coherent integrated after target envelope motion and phase compensation.This may ensure the radar range resolution.This method solves the coherent integration problem of a target range and Doppler migration with high radial velocity and acceleration.Simulations testify the validity of the new algorithm.
Properties of a monopivot centrifugal blood pump manufactured by 3D printing
An impeller the same geometry as the impeller of a commercial monopivot cardiopulmonary bypass pump was manufactured using 3D printing. The 3D-printed impeller was integrated into the pump casing of the commercially available pump to form a 3D-printed pump model. The surface roughness of the impeller, the hydraulic performance, the axial displacement of the rotating impeller, and the hemolytic properties of the 3D-printed model were measured and compared with those of the commercially available model. Although the surface roughness of the 3D-printed model was significantly larger than that of the commercially available model, the hydraulic performance of the two models almost coincided. The hemolysis level of the 3D-printed model roughly coincided with that of the commercially available model under low-pressure head conditions, but increased greatly under high-pressure head conditions, as a result of the narrow gap between the rotating impeller and the pump casing. The gap became narrow under high-pressure head conditions, because the axial thrust applied to the impeller increased with increasing impeller rotational speed. Moreover, the axial displacement of the rotating impeller was twice that of the commercially available model, confirming that the elastic deformation of the 3D-printed impeller was larger than that of the commercially available impeller. These results suggest that trial models manufactured by 3D printing can reproduce the hydraulic performance of the commercial product. However, both the surface roughness and the deformation of the trial models must be considered to precisely evaluate the hemolytic properties of the model.