大变幅盾牌座δ型变星（HADS）是变星研究中历史悠久而又受到持续关注的变星类型。我们于2009年2月对AD CMi和EH Lib进行了为期两周的观测，并对得到的数据进行了处理与分析。集合文献中的数据，我们得出的AD CMi的光变周期为0.122974500±0.000000026天。O-C分析显示，AD CMi的光变周期在变短，与以前的研究结果相反。由于观测所使用的望远镜存在问题，导致所得到的数据不能够用于频谱分析，但是我们使用Pongsak等（2007）的频率进行拟合，拟合曲线与我们的观测曲线符合良好。我们对EH Lib着重进行了频谱分析，得到了其脉动频率，除了确定脉动的基频和倍频之外，还发现一个超低频率。这为EH Lib存在的极大值的起伏和某些观测中出现的O-C的弥散提供了一个可能的解释。 NGC 1817的观测作为STEPHI联测的最新项目，于2009年在三个国家同时进行，我们使用兴隆的85厘米望远镜参加了此次联测。观测的初步结果证实了所有原先发现的盾牌座δ变星。通过对其中三颗变星的模型研究，发现NGC 1817可能是一个金属丰度相当低的贫金属星团。NGC 869与NGC 1893的联测作为NGC 884和NGC 6910在2005-2006年的成功观测之后的续作，我们也参与了其中的观测，目前数据还在处理中。 根据参与多台站国际联测的经验，我们尝试独立选择疏散星团，进行脉动变星的搜寻研究。根据一定的标准，我们选择了五个疏散星团，分别用于在云南天文台和兴隆观测站的观测。在云南天文台的观测由于望远镜出现机械故障而没有能够得到有效数据。为兴隆站的观测而准备的NGC 3231，后来被证实并不是一个疏散星团，但是我们依然对得到的数据进行了分析，结果显示，在我们的观测精度之内，视场里没有变星。

Abstract High-amplitude δ Scuti star (HADS) is a subgroup of δ Scuti star and has a relatively larger amplitude while has less pulsation modes that are much easier to detect and identify. V band photometry observations were taken to investigate the period and frequency variability of the HADS AD CMi and EH Lib during February in 2009. New period of AD CMi was derived from the data collected from both papers and observations to be 0.122974500± 0.000000026 days. Because of the poor quality of the data, we did not do frequency spectrum analysis. But still we used frequencies from former paper to fit the observed data, and found that the fitting curve and the observed data fitted well. We did frequency spectrum analysis to EH Lib, and found that besides the fundamental frequency and its harmonics, there is an ultra low frequency. International campaigns are popular during recent years, because by this means ground-based observations can avoid the 1 c/d aliasing. We take part in two international campaigns for open clusters to investigate variable stars. One is the long-lasted STEPHI campaign, and its target is the NGC 1817 which was found to be rich in δ Scuti stars. And another one is the campaign targeted at NGC 869 and NGC 1893. Preliminary results have been released for the first campaign, while data for the latter one is under processing. Several open clusters were selected as targets for observations by our own at single site. But we did not get enough data for four of them because of the telescope we used broke down. Yet another open cluster was consequently confirmed to be not an open cluster. Still we did data analysis for the collected data and found that under the limitation of our observation, there were no signs for variability for stars observed.