A new interpretation of the historical records of observing Venus in daytime with naked eye: Focusing on the meteorological factors in the astronomical observation records

Observing Venus during the daytime is challenging. However, observational data of Venus during the daytime can be found in history books from East Asian countries such as Korea, China and Japan. In this study, we are focused on data from Korean history book, and using records left in the Joseon wangjo sillok, one of the Korean history books from the Joseon dynasty (CE 1392–1910), tries to prove whether the reported observations were actual observation data. We collected these 4663 records from the Joseon wangjo sillok to determine whether they were actual observations, and to confirm the scientific validity of the records. When we looked at the distribution of observations on a yearly basis, we noticed that there were more observations in the fall and winter, while there were only limited numbers of observations in the spring. This difference in distribution suggests that observations were strongly affected by atmospheric conditions due to the weather. From the 4663 data collected, we found a cycle of about 1.6?years. The cycle of about 1.6?years is assumed to be related to the conjunction cycle of Venus. And, we found a cycle of about 1.0?years. The cycle of about 1.0?years is assumed to reflect the indirect effects of the Asian dust phenomenon. Our research result verified the record as actual observational data. In addition, this result verified that meteorological factors were involved in the recorded astronomical observation data. We think that our data can be helpful to climate studies on the natural sources of key climate-affecting aerosols.     

Extracting multiple frequencies from phase-only data

The problem of extracting multiple frequencies from phase-only data is addressed. Multiple frequency estimation is accomplished by reconstructing the Fourier transform of the complex-valued time signal and then finding peaks in the frequency domain. We present a set of conditions under which a discrete-time complex sequence can be completely specified by its phase-only information. Two candidate multiple frequency estimation schemes are introduced, one based on a closed-form least-squares inverse, the other an iterative reconstruction algorithm. The uniqueness of the closed-form solution and the convergence of the iterative scheme have been proven under certain conditions. Several examples are given, including the case where the phase is quantized as would happen in an analog-to-digital (A/D) converter. Extensions to the multidimensional case, and to the case of real-part only reconstruction are straightforward.     

Implementation of a three-phase high-power-factor rectifier with NPC topology

A three-phase four-wire power factor corrector based on neutral-point-clamped (NPC) topology is adopted to reduce the current harmonics and increase the input power factor. Using the NPC topology, the voltage stress of power switches can be reduced to the half of the dc-link voltage. With the dc-link voltage controller and the phase locked loop circuit, the balanced and sinusoidal line currents can be drawn from the ac supply system under the balance and unbalance mains voltages. The hysteresis current comparators are adopted in the current control loop to track the line current commands. Three voltage levels are generated on the ac terminal to the neutral point. Simulations and experiments are provided to verify the validity and the effectiveness of the proposed control scheme.     

ASN.1在网络拍卖系统中的应用研究

目前,很多电子商务系统之间都存在平台差异、数据差异等问题,这些问题妨碍了电子商务系统的发展。针对这一点,利用表示层的抽象描述语法ASN.1及Visual C ,设计了一个可运行在一组通过LAN连接的主从计算机上的、无平台及数据差异的拍卖系统。     

What Determines the Composition of SEPs in Gradual Events?

Gradual solar energetic particle (SEP) events are evidently accelerated by coronal/interplanetary shocks driven by coronal mass ejections. This talk addresses the different factors which determine the composition of the accelerated ions. The first factor is the set of available seed populations including the solar wind core and suprathermal tail, remnant impulsive events from preceding solar flares, and remnant gradual events. The second factor is the fractionation of the seed ions by the injection process, that is, what fraction of the ions are extracted by the shock to participate in diffusive shock acceleration. Injection is a controversial topic since it depends on the detailed electromagnetic structure of the shock transition and the transport of ions in these structured fields, both of which are not well understood or determined theoretically. The third factor is fractionation during the acceleration process, due to the dependence of ion transport in the turbulent electromagnetic fields adjacent to the shock on the mass/charge ratio. Of crucial importance in the last two factors is the magnetic obliquity of the shock. The form of the proton-excited hydromagnetic wave spectrum is also important. Finally, more subtle effects on ion composition arise from the superposition of ion contributions over the time history of the shock along the observer’s magnetic flux tube, and the sequence of flux tubes sampled by the observer.     

多向编织碳／碳复合材料力学行为研究

本文综述了作者近十年来在多向编织碳／碳复合材料力学性能研究方面的成果，包括力学模型与强度准则、热应力分析、断裂行为、性能预报与优化设计、超高温试验技术及组织性能与高温退化等内容，并分析了其存在的新问题和解决途径。     

计算机辅助机械设计的实践与研究

本文结合作者编制计算机辅助机械设计课程设计应用软件的经验，介绍了机械设计中计算机应用程序的构造、流程和数据处理方法，这些方法适用于计算量大、数据量多的设计过程。     

机动再入飞行器自适应飞行控制系统设计

研究机动再入飞行器的制导控制问题。为了解决机动再入飞行器气动系数变化范围大、气动耦合严重和气动参数非线性过零常值大等恶劣条件下的控制，并且能充分利用飞行器可测量信息提高系统自适应能力，本文提出了状态方程参数辨识－－极点配置－－前馈补偿自适应控制的飞行控制系统的设计方法。通过对新型号再入飞行器的制导系统仿真，可以看出该控制系统使其有很好的飞行性能。     

推进剂功能组分作用机理研究——(Ⅱ)丁羟/铝粉体系

在丁羟 /铝粉组成的实验体系中 ,通过测定药浆流变性的变化 ,研究了一些功能组分在推进剂中的作用机理。结果表明 ,醇胺络合物TEA·BF3 是推进剂中铝粉的偶联剂 ,在其它功能组分存在的条件下 ,仍能竞争吸附于铝粉颗粒表面。实验发现 ,在Al/HTPB/IPDI体系药浆中 ,TEA·BF3 与MAPO间存在明显的协同效应 ,使药浆流变性能显著恶化。文中对其它一些功能组分在药浆中的作用机理也进行了分析探讨。     

纤维缠绕复合材料壳体中金属嵌件的受力分析及优化设计

本文对一纤维缠绕复合材料壳体中金属嵌件进行了受力分析及形状设计。通过受力分析与设计使得复合材料与金属嵌件接触面应力分布合理化，保证了接触面的变形协调，得到了优化的金属嵌件形式。