A limited-area primitive equation model is used to study the role of the β-effect and a uniform current on tropical cyclone (TC) intensity. It is found that TC intensity is reduced in a non-quiescent environment comp...A limited-area primitive equation model is used to study the role of the β-effect and a uniform current on tropical cyclone (TC) intensity. It is found that TC intensity is reduced in a non-quiescent environment compared with the case of no uniform current. On an f-plane, the rate of intensification of a tropical cyclone is larger than that of the uniform flow. A TC on a β-plane intensifies slower than one on an f-plane. The main physical characteristic that distinguishes the experiments is the asymmetric thermodynamic (including convective) and dynamic structures present when either a uniform flow or β-effect is introduced. But a fairly symmetric TC structure is simulated on an f-plane. The magnitude of the warm core and the associated subsidence are found to be responsible for such simulated intensity changes. On an f-plane, the convection tends to be symmetric, which results in strong upper-level convergence near the center and hence strong forced subsidence and a very warm core. On the other hand, horizontal advection of temperature cancels part of the adiabatic heating and results in less warming of the core, and hence the TC is not as intense. This advective process is due to the tilt of the vortex as a result of the β-effect. A similar situation occurs in the presence of a uniform flow. Thus, the asymmetric horizontal advection of temperature plays an important role in the temperature distribution. Dynamically, the asymmetric angular momentum (AM) flux is very small on an f-plane throughout the troposphere. However, the total AM exports at the upper levels for a TC either on a β-plane or with a uniform flow environment are larger because of an increase of the asymmetric as well as symmetric AM export on the plane at radii >450 km, and hence there is a lesser intensification.展开更多
目的:基于文献计量学分析榄香烯相关研究领域的发展现状和发展态势。方法:从中国知网(CNKI)和Web of Science核心合集中检索2004—2024年榄香烯研究领域的相关文献,运用CiteSpace和VOSviewer进行文献计量学与可视化分析。结果:共纳入文...目的:基于文献计量学分析榄香烯相关研究领域的发展现状和发展态势。方法:从中国知网(CNKI)和Web of Science核心合集中检索2004—2024年榄香烯研究领域的相关文献,运用CiteSpace和VOSviewer进行文献计量学与可视化分析。结果:共纳入文献1 821篇,其中中文文献462篇,英文文献1 359篇。相比之下,英文文献发文量较大且总体呈逐年上升趋势。中英文发文量均为第一的作者为杭州师范大学的谢恬,其所在单位杭州师范大学也是英文文献发文量第一的科研机构。中英文关键词显示,榄香烯的研究热点主要集中于活性成分分析、榄香烯衍生产品和抗肿瘤作用。主要成分“β-榄香烯”为中英文文献中出现频数最高的关键词。结论:榄香烯相关研究领域目前仍处于上升阶段,发展前景良好,因此应深度剖析榄香烯的可能作用机制和临床应用,充分发挥其疗效优势和临床价值以推动中医药的传承创新发展。展开更多
文中先用硅烷偶联剂KH570对硅灰石处理得到表面硅烷化硅灰石(KH-W),再通过无皂乳液聚合得到聚甲基丙烯酸甲酯(PMMA)包覆硅灰石(PMMA-W),最后用庚二酸处理获得具有β成核作用的改性硅灰石(PA-W),分别以上述表面改性硅灰石为填料,马来酸酐...文中先用硅烷偶联剂KH570对硅灰石处理得到表面硅烷化硅灰石(KH-W),再通过无皂乳液聚合得到聚甲基丙烯酸甲酯(PMMA)包覆硅灰石(PMMA-W),最后用庚二酸处理获得具有β成核作用的改性硅灰石(PA-W),分别以上述表面改性硅灰石为填料,马来酸酐(MA)接枝聚烯烃弹性体(POE-g-MA)为增容剂,通过熔融挤出制备了聚丙烯(PP)/硅灰石复合材料,并对其结构与性能进行了研究。结果表明,添加POE-g-MA提高了硅灰石与聚丙烯基体间的相容性,硅灰石经PMMA包覆改性后与PP间的相互作用进一步增强;PA-W具有强的β成核作用,其填充聚丙烯复合材料的缺口冲击强度最高,达到了(32.76±1.53) k J/m^(2),约为纯PP的7倍;此外,与纯PP相比,PMMA-W和PA-W填充聚丙烯复合材料具有较高的延展性、储能模量、熔体强度和热稳定性。展开更多
基金sponsored by the National Natural Science Foundation of China under Grant Nos.49975014,40275018,and 40333025
文摘A limited-area primitive equation model is used to study the role of the β-effect and a uniform current on tropical cyclone (TC) intensity. It is found that TC intensity is reduced in a non-quiescent environment compared with the case of no uniform current. On an f-plane, the rate of intensification of a tropical cyclone is larger than that of the uniform flow. A TC on a β-plane intensifies slower than one on an f-plane. The main physical characteristic that distinguishes the experiments is the asymmetric thermodynamic (including convective) and dynamic structures present when either a uniform flow or β-effect is introduced. But a fairly symmetric TC structure is simulated on an f-plane. The magnitude of the warm core and the associated subsidence are found to be responsible for such simulated intensity changes. On an f-plane, the convection tends to be symmetric, which results in strong upper-level convergence near the center and hence strong forced subsidence and a very warm core. On the other hand, horizontal advection of temperature cancels part of the adiabatic heating and results in less warming of the core, and hence the TC is not as intense. This advective process is due to the tilt of the vortex as a result of the β-effect. A similar situation occurs in the presence of a uniform flow. Thus, the asymmetric horizontal advection of temperature plays an important role in the temperature distribution. Dynamically, the asymmetric angular momentum (AM) flux is very small on an f-plane throughout the troposphere. However, the total AM exports at the upper levels for a TC either on a β-plane or with a uniform flow environment are larger because of an increase of the asymmetric as well as symmetric AM export on the plane at radii >450 km, and hence there is a lesser intensification.
文摘目的:基于文献计量学分析榄香烯相关研究领域的发展现状和发展态势。方法:从中国知网(CNKI)和Web of Science核心合集中检索2004—2024年榄香烯研究领域的相关文献,运用CiteSpace和VOSviewer进行文献计量学与可视化分析。结果:共纳入文献1 821篇,其中中文文献462篇,英文文献1 359篇。相比之下,英文文献发文量较大且总体呈逐年上升趋势。中英文发文量均为第一的作者为杭州师范大学的谢恬,其所在单位杭州师范大学也是英文文献发文量第一的科研机构。中英文关键词显示,榄香烯的研究热点主要集中于活性成分分析、榄香烯衍生产品和抗肿瘤作用。主要成分“β-榄香烯”为中英文文献中出现频数最高的关键词。结论:榄香烯相关研究领域目前仍处于上升阶段,发展前景良好,因此应深度剖析榄香烯的可能作用机制和临床应用,充分发挥其疗效优势和临床价值以推动中医药的传承创新发展。
文摘文中先用硅烷偶联剂KH570对硅灰石处理得到表面硅烷化硅灰石(KH-W),再通过无皂乳液聚合得到聚甲基丙烯酸甲酯(PMMA)包覆硅灰石(PMMA-W),最后用庚二酸处理获得具有β成核作用的改性硅灰石(PA-W),分别以上述表面改性硅灰石为填料,马来酸酐(MA)接枝聚烯烃弹性体(POE-g-MA)为增容剂,通过熔融挤出制备了聚丙烯(PP)/硅灰石复合材料,并对其结构与性能进行了研究。结果表明,添加POE-g-MA提高了硅灰石与聚丙烯基体间的相容性,硅灰石经PMMA包覆改性后与PP间的相互作用进一步增强;PA-W具有强的β成核作用,其填充聚丙烯复合材料的缺口冲击强度最高,达到了(32.76±1.53) k J/m^(2),约为纯PP的7倍;此外,与纯PP相比,PMMA-W和PA-W填充聚丙烯复合材料具有较高的延展性、储能模量、熔体强度和热稳定性。
