门脉高压犬小肠微循环超微结构的变化

目的　研究门脉高压犬小肠微循环超微结构的改变。方法　行缩窄门静脉主干1/2 加丝线慢性栓塞术建立犬肝前性门脉高压症模型,观察小肠黏膜上皮和黏膜及黏膜下层微循环超微结构的改变。结果　肝前性门脉高压犬小肠黏膜及黏膜下微循环超微结构改变的特征为:血管数量增多,直径增大;微动脉腔小、壁厚,胶原纤维增生、紊乱,内皮细胞受损;微静脉腔大、壁薄,基膜及内皮细胞受损;毛细血管内皮细胞受损,白细胞浸润;肠黏膜上皮细胞、基底膜受损,回肠平滑肌细胞核畸形。结论　门脉高压犬小肠黏膜及黏膜下微循环超微结构出现明显改变。     

无碴轨道混凝土桥梁的徐变变形研究

对高速铁路无碴轨道混凝土桥梁徐变效应的分析理论进行了深入的研究，提出了适用于混凝土桥梁徐变变形的计算方法。运用该方法可以跟踪模拟桥梁在整个施工及投入运营后任意时刻的结构变形，便于在施工时合理确定二期恒载的施加时间，为我国无碴轨道混凝土桥梁的工程实践提供依据。     

自封式安全轮胎与普通轮胎装车对比道路试验

介绍了一种自封式安全轮胎的结构及工作原理,并与同规格普通轮胎进行了装车后的性能对比道路试验.试验结果表明,安装此种自封式安全轮胎车辆的动力性、经济性及平顺性等与安装普通轮胎的车辆相比无明显变化,制动性略有改善,但安全防护性能大大提高.     

Image series segmentation and improved MC algorithm

A semiautomatic segmentation method based on active contour is proposed for computed tomography （CT） image series. First, to get initial contour, one image slice was segmented exactly by C-V method based on Mumford-Shah model. Next, the computer will segment the nearby slice automatically using the snake model one by one. During segmenting of image slices, former slice boundary, as next slice initial contour, may cross over next slice real boundary and never return to right position. To avoid contour skipping over, the distance variance between two slices is evaluated by an threshold, which decides whether to initiate again. Moreover, a new improved marching cubes （MC） algorithm based on 2D images series segmentation boundary is given for 3D image reconstruction. Compared with the standard method, the proposed algorithm reduces detecting time and needs less storing memory. The effectiveness and capabilities of the algorithm were illustrated by ,experimental results.     

D20发动机多楔带的研究

结合D20发动机前端轮系的设计与开发工作,介绍D20发动机前端轮系的布置与参数,多楔带的布置方案,多楔带校核等相关设计内容,并对设计中出现的问题进行了讨论。经过450h发动机台架强化实验表明,D20发动机性能指标满足设计要求。     

对电气化铁路相关设备的采购工作及供应商选择的初步探讨

在铁路跨越式大发展的今天，高速铁路特别是电气化铁路成为当仁不让的幸运者。自2004年秦沈客运专线建成通车以来．经过广大科研生产人员的不懈努力．中国已成为继法国、德国、西班牙，日本、韩国、中国台湾等国家和地区之后．拥有并全面掌握高速铁路设计、制造、施工、运营、维护技术的国家之一，电气化铁路设计、施工、集成技术也在跨越式发展当中．对电气化铁路相关设备的采购工作也提出了新要求。     

六点式安全带防护效率试验研究

利用Hybrid Ⅲ 50th假人佩戴六点式安全带进行了前碰撞试验,并对比分析了三点式安全带约束下的头部和胸部损伤值.在试验基础上,又进行了Hybrid Ⅲ 50th假人仿真对比分析.结果表明,六点式安全带较三点式安全带头部和胸部损伤值明显降低,尤其是胸部压缩值.分析指出,进一步优化安全带的强度和材料参数可以获得更好的保护效果.     

轨道交通站域步行系统优化研究

城市轨道交通的建设是老旧街区转型发展的重要契机,一方面引导居民出行方式,提高出行便利度,另一方面对轨道站点周边空间进行更新改造,补充完善公共服务设施,打造高品质的公共空间环境。本文以重庆南岸区海棠溪轨道站步道为例,从轨道站步行系统安全性、便捷性、舒适性的角度,提出优化步行通道的措施,对改善居民轨道接驳交通出行具有重要意义。     

Fuzzy sliding mode control method for vertical motion of autonomous underwater gliders北大核心CSCD

［Objective］This paper proposes a fuzzy sliding mode controller based on T-S fuzzy logic for the vertical plane motion control of an autonomous underwater glider (AUG) with limited actuator capability. ［Methods］In the fuzzy sliding mode controller, the fuzzy switching rate is used to replace the switching rate in the fixed time controller to effectively suppress buffeting. The fuzzy switching rate is obtained by fitting the switching rate of the fixed time controller with T-S fuzzy rules. Based on the limited capabilities of AUG actuators, a saturation auxiliary system is designed to improve the actuator saturation effect. Finally, the performance of the system is verified by Lyapunov stability analysis and numerical simulation. ［Results］The results show that the AUG under the fuzzy sliding mode controller and the saturation auxiliary system can converge in finite time. The effectiveness of the fuzzy sliding mode controller and the saturation auxiliary system are verified by numerical simulation. ［Conclusions］By making comparisons with the fixed-time controller, it is verified that the two controllers have similar control performance, and the buffeting of the fuzzy sliding mode controller is lesser. © 2022 Journal of Clinical Hepatology. All rights reserved.