The low-altitude photogrammetry technology of unmanned aerial vehicles (UAVs) is widely used in many fields, but the absence of analysis and research affects the accuracy of its data products. At the same time, low-altitude photogrammetry faces the problem of low elevation positioning accuracy. The network space triangulation adjustment in the beam technique region is considered to eliminate perspective distortion in non-overlapping areas. This paper explains the key technologies of low-altitude photography and remote sensing mapping of UAVs, rectifies the distortion difference of remote sensing images, and then carries out grid division on the image according to the improved APAP (as-projective-as-possible warp) matching method. Next, it solves each grid homography matrix, linearizes the homography matrix, and carries out image matching according to the linearized homography matrix, which can effectively weaken the ghosting phenomenon during image matching. The network space triangulation adjustment in the beam technique region is considered to eliminate perspective distortion in non-overlapping areas. The two measurement areas’ accuracy level is analyzed using digital line drawing and digital orthophoto images (DOIs). Finally, the experimental results indicate that the image matching algorithm proposed in this paper has strong reliability and can substantially increase photogrammetric elevation positioning.

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With the slice tool in finite element software Magnet, 3D magnetic field distribution in airgap of an axial flux permanent magnet motor (AFPMM) is studied. Then analytical method, finite element method and average radius method are used to calculate the airgap magnetic flux of per pole respectively. The results which are gotten through these methods are approximate and can reflect per pole magnetic flux of AFPMM generally. The above research has achieved anticipated effect and provided a basis for the calculation of AFPMM airgap magnetic field.

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With the development of high-speed permanent magnet synchronous motors (PMSM), the requirements for speed are getting higher and higher, and the power density increase is getting bigger and bigger. However, too high a loss density will cause motor heat dissipation difficulties, resulting in motor insulation aging and permanent synchronous magnet demagnetization failure, which seriously affects the safe operation of the motor. Therefore, it is necessary to analyze the fluid field and temperature field for oil-cooled high-speed PMSM. In this paper, a 40 kW back-wound oil-cooled high-speed PMSM is used as the research object. Firstly, a three-dimensional fluid-solid coupled heat transfer model of high-speed PMSM is established based on the parameters of the motor, and the fluid flow characteristics inside the motor are analyzed based on fluid dynamics and heat transfer theory, and then the overall and local temperature rise distributions of the motor are compared and analyzed to reveal the influence of the temperature rise of each component inside the high-speed permanent magnet synchronous motor after being cooled by the cooling structure. Secondly, based on the finite element model, the motor temperature rises and oil flow characteristics with oil flow rate are analyzed to come up with an optimized solution. Finally, the accuracy of the analysis method is verified by conducting temperature rise experiments on the prototype.