考虑潜在威胁区的航天器最优规避机动策略

随着一系列轨道转移飞行器的工程化实施,航天器可能面临的非合作交会威胁日趋严重。针对该问题,根据交会机动的特点定义了新的规避机动指标——潜在威胁区,相较于传统的相对距离和碰撞概率等规避指标,潜在威胁区更适合航天器在面对非合作交会追踪器时进行规避机动,能够有效提升航天器的抗交会能力。首先,建立追踪器多脉冲最优交会模型,以此为基础给出潜在威胁区的定义与计算方法;然后,以潜在威胁区弧长为优化目标,建立了目标器最优规避模型,采用遗传算法进行目标优化;最后,根据所建立的双层优化模型进行数值仿真,以初始相距100km为初始条件进行仿真并计算得到了使潜在威胁区为零所需规避脉冲值,验证了文中模型的正确性,结果显示所定义的潜在威胁区弧长随着规避脉冲的增大呈严格的单调递减关系。研究为在轨航天器在面对非合作交会时提供了有效的规避策略,提升了航天器的空间生存能力。

Impacts of Globalization： Hegemonic Threats of English in Taiwan

With the spread of globalization and information technology, the status of English as a lingua franca worldwide is undisputable. Consequently, the impact of globalization on ELT （English language teaching） is phenomenal. In responding to the impact of global competitors and internationalization, English teaching is often regarded as a principal issue in education. English education is treated as a tool to keep up with the rapid globalization of the world economy. Discussing ELT in Taiwan as an example, this paper aims to raise caution among the periphery educators that under the impact of globalization, the imposition of western culture and language via ELT could be potentially hegemonic and harmful to the local culture and language. This paper will be organized into three parts. Firstly, the impact of globalization on the dominance of English will be discussed. Secondly, the potential threats of linguistic hegemony via ELT will be analyzed. Thirdly, proactive solutions to the hegemonic threats of ELT are proposed as the key to ride out the wave of globalization.