时钟误差对太阳高度推算误差的影响

基于采用Ｊ２０００．０作为太阳赤道坐标的起算基准,而得到的太阳赤道坐标的高精度数学模型,分析了时钟误差引起太阳赤纬,赤经的推算误差值;又根据ＧＰＥＳ１型电子六分仪中的太阳格林时角数学模型 时钟误差引起多大的太阳格林时角的推算误差;最后利用航海天文学有关公式,论述了时钟误差产生的天体高度推算误差的情况。     

Influence of hot-rolling on the microstructure and mechanical properties of a near β-type Ti-5.2Mo-4.8Al-2.5Zr-1.7Cr alloy

In this work, the 90° clock rolling and the uni-directionally rolling processes at high temperature were carried out on the near β-type Ti-5.2Mo-4.8Al-2.5Zr-1.7Cr titanium alloy cutting from an ingot, respectively. The corresponding microstructures were quantitatively characterized, and its effect on the dynamic mechanical properties and fracture mechanism were emphatically investigated. It was found that after 90° clock rolling, the microstructure composed of equiaxed primary α phase(α_p) with an average size of about 2 ?μm and the β transformed regions containing the acicular secondary α phase(α_s) with an average thickness of about 50 ?nm and the separated β phase was obtained. However, in the uni-directionally rolled titanium alloy, no acicular α_s was observed, and the corresponding microstructure consisted elongated lamellar α phase (average thickness: about 1.3 ?μm), few equiaxed α phase (average grain size: about 300 ?nm) and the inlaid β phase. The microstructural difference of the hot-rolled titanium alloys was closely related to the deformation process. Moreover, a great number of α_p and α_s in the 90° clock rolled titanium alloy effectively enhanced the strength, and the dynamic compressive strength reached to 1730 ?MPa. Furthermore, equiaxed α_p was conducive to the homogeneous deformation, which counteracted the localized deformation caused by acicular α_s to a certain extent and made the 90° clock rolled titanium alloy exhibit an acceptable critical fracture strain of about 10.5%. Moreover, the fracture microstructures showed that the main failure mode of the 90° clock rolled and the uni-directionally rolled titanium alloy were ductile fracture and brittle fracture, respectively.     

无线传感器网络中一种基于安全性的时钟同步算法

无线传感器网络可以部署在各种危险的环境里,虽然风险性比较大,但是如果能够顺利完成任务,完全有可能延长安全时间。在保证安全的情况下,能够提高无线传感器工作有效性的新的算法——时钟算法。它主要是将网络中的恶意、不良的信息发现以后及时删除处理。此种方法能够使发恶意信息的网站有一定的收敛,并且时间精确。这种算法已经经过了许多的仿真实验,得出来的结论是这个算法是可以使用的。     

紧密耦合的多8096单片机系统

在实时控制和实时处理领域，有时需要多任务嵌入式系统．本文介绍一种具有该功能的紧密耦合多8096单片机系统的实现方法．着重阐述了构成该多机系统的控制电路、系统规模扩充的原理及系统全局时钟的设计．系统已经实际应用于工程项目中．