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The old urban district is the carrier of urban development, and its protection and renewal is of great significance for urban construction. This study with a view to protecting and renovating the old urban district by the boundary space design, taking Chengdu Yulin district as an example, proposing the "boundary thickening" strategy, and put forward the complete walking system, multiple public space, LID water purification corridor and compound functional wall four specific design measures, in order to enhance the space vitality of the entire district through the transformation design of the boundary space. It will help the protection and renewal of the old urban district, and provide some reference for the design of the same type of block boundary space in the future.

Our Purpose is to study the effects of intraocular pressure (IOP) and aspheric transition zone (ATZ) on corneal biomechanics after pure hyperopia correction by using the finite element analysis (FEA). The values of IOP were changed, and 1-5# aspheric transition zones were designed in 1-5D hyperopia correction model. Simulate and calculate the wavefront aberration, stress and vertex displacement of cornea. The results show that with the increase of IOP and diopter, defocus increases positively and sphere increases negatively. Diopter and IOP have slight influence on coma. At 22mmHg, the maximum value of defocus was 1.367mm at 5D-1#, and the maximum value of sphere was -0.32mm at 5D-5#. IOP and diopter have great influence on the stress in the marginal region of the anterior corneal surface, and 1D-1 # has the maximum value at 22mmHg. With the increase of IOP and diopter, the vertex displacement of posterior corneal surface increased. The ATZ ablation profile has little effects on the wavefront aberration and displacement. We can draw a conclusion that refractive surgery destroys the physiological structure of cornea and has a great influence on the biomechanical properties of cornea. IOP plays an important role in maintaining the physiological structure of cornea.

The three-dimensional (3D) finite element model of human eye was established, and the intraocular pressure (IOP) was loaded to simulate refractive surgery. The biomechanical properties of human cornea after SMILE and LASIK surgery were studied from the stress, strain and induced wavefront aberration. Our results showed that SMILE had less impact on the biomechanics, having less stress and strain changes than LASIK. However, the stress and strain of the cornea increased with the increase of the diopter and were concentrated in the central region. We also investigated the changes in wavefront aberrations of the cornea after surgery, and the results indicated that the defocus and vertical commotion were significantly affected by SMILE and LASIK surgery, while the remaining aberrations were approximately unchanged. In conclusion, both SMILE and LASIK sergury procedures changed the postoperative corneal biomechanics, but SMILE had less impact on the biomechanics of corneal.

The finite element method is used to simulate the optical coherent elastic imaging in Agar. The shear wave velocity in Agar was measured by ARF-OCE system, and then the Agar model was established by finite element method, and then the shear wave velocity in Agar model was measured. The shear wave velocity in experiment and finite element simulation were compared and analyzed. The shear wave velocity obtained in the experiment is 2.50 m/s, and the range of shear wave velocity obtained in the finite element simulation is 2.4802m/s, and the average wave velocity is 2.5167m/s. The finite element method can express tissue elasticity directly and clearly, and it plays a great guiding role in corneal elastography.

The three-dimensional finite element model of the postoperative whole human eye after small incision lenticule extraction (SMILE) surgery and the axisymmetric air-puff model were established, the influencing factors in the Air-puff test were explored from the displacement nephogram on anterior corneal surface. Our results showed that the maximum depression displacement was positively correlated with the corrected diopter when the peak pressure of ejection and air-puff center location were constant, but the highest concavity radius of concave curvature was negatively correlated with the corrected diopter. At the same time, we also found that when the decentration of air-puff center position was 1mm, the maximum depression displacement of the anterior corneal surface was reduced by 8.3% under the condition of constant correction diopter and peak air-puff pressure, compared with the maximum depression displacement of the anterior corneal surface when the decentration of air-puff center position was 0 mm. In conclusion, the corrected diopter and decentration of air-puff position have an important effect on the results of air-puff test after SMILE.