摘要：介绍了交流伺服螺旋精压机的机械结构及工作原理,并对其控制系统进行了研究和分析,提出了控制系统的三种设计方案,最后进行了控制方案的比较和选择。

摘要：In this paper, a numerical simulation of the traditional graded distributed Bragg reflector (DBR) and a design of the novel DBR with short period superlattices (SPSs DBR) used by vertical cavity surface emitting laser (VCSEL) are reported. First, the optical characteristic matrix of the graded DBRs is derived using the theories of thin film optics. Second, its reflective spectrum is numerical simulated and it is found that the simulative results are similar with the experimental data. The difference of the cavity mode position between the experimental and simulative data is discussed. Finally, based on the simulative results of graded DBR, a novel DBR with 4.5-pair GaAs/AlAs SPSs is designed, and its reflective spectrum is numerical simulated and analyzed.

摘要：目的 评价医务人员预防SARS医院内感染个人防护措施的效果,验证SARS的传播途径。方法 在广东省10家收治SARS患者的主要医院进行了成组设计的病例对照研究,对象为常规参加SARS诊治工作且直接抢救重患者的医护人员,共257人,其中病例组77例,对照组180人。采用统一调查表了解调查对象接触SARS患者程度、个人防护情况、卫生习惯、预防服药等方面情况。单因素分析采用X2检验、多因素分析利用非条件logistic回归分析。并用趋势X2检验分析个人防护措施的剂量反应关系和联合使用效果。结果 单因素分析结果显示,一直戴12层及以上口罩、穿隔离衣、用鞋套、戴手套、必要时戴眼罩、消毒洗手、漱口液漱口、用滴鼻滴眼液保护鼻眼黏膜、及时洗澡换衣、“不在病区吃饭/饮水/抽烟”、服oseltamivir phosphate等均有保护作用(P<0.05)。非条件logistic多因素回归分析有显著意义的有戴口罩(OR=0.78,95％CI:0.60～0.99)、戴眼罩(OR=0.20,95％CI:0.10～0.41)和穿鞋套(OR=0.58,95％CI:0.39～0.86)。并且趋势分析显示口罩及口罩类型、穿隔离衣、用鞋套、戴手套、必要时戴眼罩、漱口液漱口、用滴鼻滴眼液保护鼻眼黏膜和及时洗澡换衣等措施存在剂量效应关系。无防护参与SARS患者抢救的医护人员的罹患率高达61.5％(16/26)。