期刊文献+
共找到3篇文章
< 1 >
每页显示 20 50 100
黏接界面性能劣化的非线性超声检测研究进展 被引量:5
1
作者 李立 焦敬品 +3 位作者 高翔 贾召会 吴斌 何存富 《科学通报》 EI CAS CSCD 北大核心 2022年第7期621-629,共9页
作为传统机械连接的重要补充形式,黏接结构在工业领域应用广泛.在外载及环境因素的综合作用下,黏接界面的性能会出现劣化,严重影响黏接结构的安全使用.因此,黏接界面性能检测一直是无损检测领域的热点和难点问题.线性超声技术能有效实... 作为传统机械连接的重要补充形式,黏接结构在工业领域应用广泛.在外载及环境因素的综合作用下,黏接界面的性能会出现劣化,严重影响黏接结构的安全使用.因此,黏接界面性能检测一直是无损检测领域的热点和难点问题.线性超声技术能有效实现黏接界面中分层、脱黏等损伤的检测,但难以实现黏接界面早期劣化(如界面闭合缺陷、界面弱黏接等)的检测及定量评价,而非线性超声技术可以克服传统线性超声技术在检测灵敏度方面的不足,有望成为一种有效的黏接界面性能早期劣化的检测手段.本文从理论模型和检测实验两方面对非线性超声技术在黏接界面性能检测与评价方面的研究进展进行了综述.从界面的接触非线性和中间层的材料非线性角度出发,介绍了界面非线性超声检测相关理论的简化模型,如非线性弹簧模型、界面接触模型及考虑中间层厚度的接触模型等.这些模型可用于描述超声波在弱黏接界面处产生的多种声学非线性效应,如二次谐波产生、混频和非线性谐振等,但需要进一步研究不同模型对超声波在弱黏接界面处非线性传播行为的描述能力.同时,介绍了非线性谐振、混频和二次谐波3种非线性技术在界面性能实验检测方面的研究进展.最后,对黏接界面性能劣化非线性超声检测技术的发展进行了展望. 展开更多
关键词 黏接界面 性能劣化 非线性超声 接触非线性 材料非线性 无损检测
原文传递
Complex effects of different types of acid rain on root growth of Quercus acutissima and Cunninghamia lanceolata saplings
2
作者 Xin Liu Shilin Ma +6 位作者 zhaohui jia Muhammad Ramzan Miaojing Meng Jinping Wang Chong Li Yinlong Zhang Jinchi Zhang 《Ecological Processes》 SCIE EI 2022年第1期51-64,共14页
Background:Soil acidification caused by acid rain(AR)can damage plant roots,which in turn negatively impacts plant health.In response to changing AR types,research efforts to elucidate their specific impacts on plants... Background:Soil acidification caused by acid rain(AR)can damage plant roots,which in turn negatively impacts plant health.In response to changing AR types,research efforts to elucidate their specific impacts on plants have become intense.Methods:For this study,we investigated the effects of simulated sulfuric,nitric,and mixed AR on the root systems of Quercus acutissima Carr.and Cunninghamia lanceolata(Lamb.)Hook.under different acidity levels.Results:As the AR S/N ratio and pH decreased,the height growth rate(HGR),basal diameter growth rate(DGR),total root length(TRL)and total root surface area(TRS)of C.lanceolata decreased,whereas the TRL and TRS of Q.acutissima remained the same.When the NO_(3)^(−)concentration in AR was increased,the root activity,superoxide dismutase(SOD)and catalase(CAT)activities of C.lanceolata roots revealed a downward trend;however,the root activity of Q.acutissima and the peroxidase(POD)activity of C.lanceolata roots revealed an upward trend.Further,redundant analysis and structural equation models indicated that AR pH had a greater impact on the HGR of Q.acutissima than that of C.lanceolata,while the impact of the AR S/N ratio on C.lanceolata growth rates was greater than that of Q.acutissima.Conclusions:Our results suggested that the root systems of different tree species had variable responses to AR,and the AR S/N ratio was an important factor affecting plant root growth.This might facilitate new strategies for the culti‑vation and protection of plantations in the future. 展开更多
关键词 Sulfuric and nitric acid rain Root growth Root morphology Root activity Antioxidant enzyme activity
原文传递
Development of solid base catalyst X/Y/MgO/-Al_(2)O_(3) for optimization of preparation of biodiesel from Jatropha curcas L.seed oil
3
作者 Rui WANG Song YANG +7 位作者 Shitao YIN Baoan SONG Pinaki SBHADURY Wei XUE Shuwei TAO zhaohui jia Da LIU Liang GAO 《Frontiers of Chemical Science and Engineering》 SCIE EI CSCD 2008年第4期468-472,共5页
The preparation and regeneration conditions of the identified catalyst X/Y/MgO/?-Al2O3 with high catalytic activity were studied and optimized. The biodiesel was prepared by transesterification of Jatropha curcas see... The preparation and regeneration conditions of the identified catalyst X/Y/MgO/?-Al2O3 with high catalytic activity were studied and optimized. The biodiesel was prepared by transesterification of Jatropha curcas seed oil produced in Guizhou with methanol at its reflux temoerature in the presence of X/Y/MgO/?-Al2O3 . The pilot plant tests were carried out in a 100 L reaction vessel. Both average yield and fatty acid methyl esters (FAME) content reached more than 96.50% under the optimum reaction conditions of the pilot plant tests designed with an oil/methanol molar ratio of 1 : 10, catalyst concentration of 1.00%, and reaction time of 3 h at reflux temperature. In addition, analysis shows that the quality of biodiesel meets the standard EN 14214. 展开更多
关键词 Solid base catalyst Jatropha curcas oil Transesterification reaction Pilot plant test
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部