Comparison of preoperative simulated and postoperative real safety distances using anterior segment OCT in patients with phakic IOL according to iris configuration

AIM:To compare the simulated safe distance(SSD)preoperatively versus real safe distance(RSD)postoperatively in patients with iris-claw phakic intraocular lens(p IOL)implantation according to iris configuration.METHODS:Totally 60 eyes of 60 patients underwent p IOL implantation for surgical correction of myopia.Anterior chamber depth(ACD)was measured with the IOLMaster 700,and nasal and temporal safety distances(SD)were measured pre-and postoperatively using Anterior Segment Visante-OCT.SD was defined as a line measured between the edge of the optic or its simulated image to the endothelium.Eyes were divided into 3 groups:convex,concave,and plane according to preoperatory iris configuration.Statistical analysis was performed using the R program,for the comparison of independent groups and multiple comparisons,the Kruskal-Wallis test and the Dunn test were used respectively.RESULTS:Mean difference between nasal preoperative SSD and postoperative RSD was-0.36±0.38,-0.29±0.48,and-0.18±0.30 mm in the concave,convex,and plane group,respectively.Mean difference between temporal SSD and RSD was-0.36±0.37,-0.14±0.38,and-0.24±0.33 mm in the concave,convex,and plane group,respectively.There were statistically significant differences between SSD and RSS for both nasal and temporal sides in the concave and plane group(P<0.002).CONCLUSION:Preoperative SSD and postoperative RSD for iris-claw p IOL shows significant differences in patients with concave and plane iris.

Interaction analyses between tunnel and landslide in mountain area

This paper focuses on the analytical derivation and the numerical simulation analyses to predict the interaction influences between a landslide and a new tunnel in mountain areas. Based on the slip-line theory, the disturbance range induced by tunneling and the minimum safe distance between the tunnel vault and the sliding belt are obtained in consideration of the mechanical analyses of relaxed rocks over the tunnel opening. The influence factors for the minimum safe crossing distance are conducted,including the tunnel radius, the friction angle of surrounding rocks, the inclination angle of sliding belt,and the friction coefficient of surrounding rocks. Secondly, taking account of the compressive zone and relaxed rocks caused by tunneling, the Sarma method is employed to calculate the safety factor of landslide. Finally, the analytical solutions for interaction between the tunnel and the landslide are compared with a series of numerical simulations, considering the cases for different perpendicular distances between the tunnel vault and the sliding belt. Resultsshow that the distance between the tunnel vault and the slip zone has significant influence on the rock stress and strain. For the case of the minimum crossing distance, a plastic zone in the landslide traversed by tunneling would be formed with rather large range, which seriously threatens the stability of landslide. This work demonstrates that the minimum safe crossing distance obtained from numerical simulation is in a good agreement with that calculated by the proposed analytical solutions.

Stochastic model updating using distance discrimination analysis

This manuscript presents a stochastic model updating method, taking both uncertainties in models and variability in testing into account. The updated finite element（FE） models obtained through the proposed technique can aid in the analysis and design of structural systems. The authors developed a stochastic model updating method integrating distance discrimination analysis（DDA） and advanced Monte Carlo（MC） technique to（1） enable more efficient MC by using a response surface model,（2） calibrate parameters with an iterative test-analysis correlation based upon DDA, and（3） utilize and compare different distance functions as correlation metrics. Using DDA, the influence of distance functions on model updating results is analyzed. The proposed stochastic method makes it possible to obtain a precise model updating outcome with acceptable calculation cost. The stochastic method is demonstrated on a helicopter case study updated using both Euclidian and Mahalanobis distance metrics. It is observed that the selected distance function influences the iterative calibration process and thus, the calibration outcome, indicating that an integration of different metrics might yield improved results.

An Improved Underwater Confrontation Simulation Method of Naval Amphibious Operational Training System

This paper described an improved underwater confrontation simulation method of naval amphibious operational training system. The initial position of submarine forces on the enemy is generated automatically, and the attacking distance model of torpedoes is established based on the kinematics theory, which is more flexible and reasonable to judge the launch condition compared to traditional method. The two kinds of confrontation behavior models on the enemy submarine are created to depict its tactical action from the defensive to the offensive as well as the contrary, ensuring that operational style is simulated more comprehensively and properly. The existing motion trajectory estimation and collision detection algorithms on operational platforms are also improved to reduce the iteration error and further enhance the detection accuracy of target hit.