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多轴齿形链系统曲线张紧约束布局设计及其张紧特性的研究
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作者 范成岩 许树新 +1 位作者 王洪军 邢建恒 《机械传动》 CSCD 北大核心 2016年第11期16-19,共4页
曲线张紧是汽车发动机正时链系统的常见约束方式,其布局设计直接关系到正时链系统的振动特性、噪声特性、平顺特性。通过某款发动机正时齿形链系统设计实例,解析了三轴系统的链条张力特点,并进行了张紧器的张紧力与松边张力的定量描述... 曲线张紧是汽车发动机正时链系统的常见约束方式,其布局设计直接关系到正时链系统的振动特性、噪声特性、平顺特性。通过某款发动机正时齿形链系统设计实例,解析了三轴系统的链条张力特点,并进行了张紧器的张紧力与松边张力的定量描述。通过缸盖反拖系统试验台测试了不同转速条件下的张紧力,以及特定转速的曲轴转矩,得到了正时链系统的载荷循环特性。结果表明,在保证正时链系统动力性能的基础上,张紧约束应综合考虑吸纳正时链的磨损伸长,以及张紧力的施力方向,还要兼顾正时链的静强度安全裕度。研究结论对链条在汽车发动机中的应用具有重要意义,同时对多轴系的链传动系统设计也具有一定的借鉴作用。 展开更多
关键词 正时齿形链 曲线张紧 布局设计 特性
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Usefulness of dynamic contrast-enhanced MR imaging in the evaluation of pulmonary isolated lesions 被引量:3
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作者 Zhiyong Li Tingting Zhang Jianlin Wu Wei Liu Qiang Wei Bin Xu Rui Han 《The Chinese-German Journal of Clinical Oncology》 CAS 2010年第6期334-336,共3页
Objective: The aim of our study was to investigate the value of dynamic contrast-enhanced MRI for evaluating differential diagnosis of pulmonary isolated lesions. Methods: Twenty-nine consecutive patients enrolled i... Objective: The aim of our study was to investigate the value of dynamic contrast-enhanced MRI for evaluating differential diagnosis of pulmonary isolated lesions. Methods: Twenty-nine consecutive patients enrolled in this study, all of whom underwent DCE-MRI examinations and received a histologic and clinical diagnosis. Among these, lung tuberculoma 7 cases, harmatoma 3 cases, peripheral lung cancer 19 cases. DCE-MRI was acquired with 3D LAVA technique, total 18 phases were acquired, scanner time of per phase was 5-7″. After contrasting agent, twice successive scanning was acquired at 10″ and 50″. Then 1′30″, 2′, 2′30″, 3′, 3′30″, 4′, 5′, 6′, 7′, 8′, 9′, 10′, 11′, 12′ performed scanning. Region of interest was placed on the Maximum level in the tumors. According to Schaefer's standard, four types of time signal intensity curve (TIC) were classified, which were A, B, C and D. Compared the dynamic parameters between benign and malignant nodules. Results: Lung tuberculoma may display three curves: A type 1 case, ring-shaped enhancement 4 cases (periphery ring A type, central region D type), D type 2 cases. Harmatoma may display three curves: A type 1 case, C type 2 case. Peripheral lung cancer may display A type. Except 2 cases D type lung tuberculoma, we compared curve data of 8 cases benign nodules (including tuberculoma Atype and periphery ring Atype, harmatoma Atype and C type) and lung cancer. SlEP%: benign nodules 0.7885 ±0.5543, lung cancer 1.2623 ±0.3059, P 〈 0.05; MER: benign nodules 1.0007 ± 0.4251, lung cancer 1.3694 ±0.2740, P 〈 0.05; washout: P 〉 0.05. Conclusion: Lung MR imaging is helpful to diagnosis and differential diagnosis of isolated benign and malignant nodules. SIEP% and MER could offer valuable information. The evolution of global tuberculosis may be from A type to ring-shaped ennoblement to D type. It was easy to do right diagnosis to lung tuberculoma with ring-shaped ennoblement and D type. Peripheral lung cancer commonly displayed A type and needed identification with acute inflammation. So, it is important to anti-inflammatory follow-up for a few A type nodules. 展开更多
关键词 non-small cell lung carcinoma dynamic contrast-enhanced MRI time signal intensity curve diagnosis
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