在帆船时代,中外船只进出珠江口的航线主要集中在大西水道、担杆水道和大屿山水道。中国船民最早开发和利用这些水道,而外国人在很长一段时间里对这些水道的地理状况知之甚少。所以外国船只经过上述水道前往广州和澳门或由此返航时,一般由中国船民充当＂引水＂为其领航。这些船民受沿海州县管理,并向官府提供外国船只在珠江口活动的情报。19世纪初英国东印度公司组织人力物力对这些水道进行了详细的勘探,据此编制了准确的地图和航海指南,记录了水道的地理状况和航行方法。随着地图和航海指南的推广应用,外国船只摆脱了对中国船民的依赖,较为
The Duffing equation describes the oscillations of a damped nonlinear oscillator [1]. Its non-linearity is confined to a one coordinate-dependent cubic term. It
<正> 关于辽代省制问题,中外学者都曾有过研究,并取得一些重要成果,但由于古代史书对辽代省制的记载失误和疏漏太多,仍有许多问题值得探讨。本文试就辽代省制体系问题作粗浅分析,以祈方家指正。 辽建国之初,太祖耶律阿保机因名而设的汉官,是直承晚唐、五代官制体系。对从后唐入辽的官吏,给予后唐的高官职。如康默记为左尚书,韩延徽守政事令,王郁为同政事门下平章事。实际上,凡藩汉相涉事及汉制建设,皇帝都参用他们的建议并利用他们扩大军事征服,安定新占领汉人地区的社会秩序,他们的官称和实际职掌并不相符。这时,辽
A novel 4 by 4 array of electromagnetic micro-actuators operating on the principle of voice-coil actuators is presented. The intended application of the array i
We have theoretically studied the modal dispersion equation and effective refractive index of one-dimensional plasma photonic crystals (1-D PPCs) having differe
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As permanent magnet motors and generators produce torque, vibration occurs through the small air gap due to the alternating magnetic forces created by the rotat
This paper presents a modeling and an analysis of one-dimensional periodic structure composed of a cascade connection of N cells considered as infinite. The ABC
In this article, we have given a review of thallium based (TlmBa2Can-1CunO2n+2) and copper based (CuBa2Can-1 CunO2n+4) high temperature superconductors. This re
In order to realize the micromation of position sensors, and extend the application area into micro scale, this paper designs a novel micro position sensor, Mac