Estimation and Optimization of the Principal H-Maser Parameters

The scale along the coordinate axes in the equations of motion hitherto used for an H-maser (in relative units) is shown to depend on Q as the quality factor for an H-maser. This hinders both analysis of the operation of the H-maser and optimization of its parameters. The modified equations of motion proposed here do not have that shortcoming. We determine the atomic flux into the bulb that gives the H-maser the best metrological characteristics.     

Failure analysis of a broken tooth

Several days after heart surgery, a patient discovered his upper right canine tooth had broken at the root. Such tooth damage, recognized post-operatively, is usually assumed to be caused by blunt mechanical force from an instrument used by the anesthesiologist during placement of a breathing tube at the start of surgery. In this case, the patient had saved the crown portion of the broken tooth, and it was possible to examine the root fracture characteristics. The curvature and direction of the crack path and natural tooth situation suggested that failure could be described through a cantilever beam model. This was confirmed when a whole extracted sample tooth was embedded and broken by a measured force in a manner consistent with the model. The resulting fracture surface matched that of the patient’s broken canine tooth. However, the high load and force direction necessary to fracture the root was inconsistent with forces applied during the anesthesia procedure. The failure analysis and further investigation indicated tooth clenching on the breathing tube during recovery was the likely cause of fracture. This paper presents an alternate explanation for intubation-related dental injury, demonstrates the practicality of fractographic analysis of biological materials, and introduces a methodology for simulating in vitro tooth settings for mechanical testing.     

基于WVD的防空雷达直升机信号特征分析

基于直升机目标旋转部件的调制模型，本文针对防空雷达提出了分析直升机信号特征的一种新方法——WVD法，并对直升机目标旋转部件调制回波信号在不同噪声情况下加以仿真分析，结果表明：用WVD分析雷达回波中直升机信号特征是一种非常有效的方法。     

饼干炉湿度控制的改进方法

在大空间的温度控制系统中 ,采用简单的PID控制规律 ,对空间的温度、湿度进行解藕计算 ,将空间的相对湿度控制转化为送风含湿量的控制。该控制方式稳定、可靠 ,并且节约能源。本方法适用于所有的烘烤炉中     

天然气井井筒及井口安全技术研究

天然气勘探开发具有高温、高压、高风险,安全技术及管理难度大等特点,通过实例分析天然气井存在的主要问题,提出应采取的关键安全技术及需要解决的问题。     

在广西全面开展悬移质泥沙简测的可行性和重要性

通过对百色等水文站泥沙资料分析 ,并结合广西河流及泥沙特性和社会对泥沙资料的精度要求 ,得出了在广西实行悬移质泥沙简测的可行性。为满足广西国民经济可持续发展需要 ,提出了在广西改革悬移质泥沙测验方式的必要性和紧迫性     

乡镇供水工程设计中应注意的若干问题

乡镇供水作为水利开发建设中的一个新领域，设计工作是龙头，有许多技术问题需要研究和探索，阐述了乡镇供水工程设计应注意的若干问题，并对设计中存在的一些具体问题进行了分析和探讨。     

丙烯腈－苯乙烯共聚物水解磺化产物对泥浆的稳定作用

在实验室条件下对用丙烯腈－苯乙烯共聚物在硫酸存在下的水解磺化产物（ＨＳＡＳ）处理的泥浆性能进行了评定。ＨＳＡＳ处理的泥浆有较小的滤失性，较好的耐盐和抗高温性。     

利用黄河泥沙加固下游大堤

黄河是一条举世闻名的多泥沙河流，善淤、善决、善徒给沿河人民带来对过深重灾难，防洪问题一直是国家的心腹之患。泥沙问题是黄河防洪问题的症结所在。在总结固大堤经验的基础，进行挖河疏浚，淤筑“相对地下河”，已作为黄河治理的一项重大决策付诸实施。     

利用信息融合方法的三维特征提取

本文提出了一种基于信息融合的物体三维特征的提取方法，该方法利用两幅互相配准的三维测距图像和灰度图像，来提取多面体的三维特征。首先，通过分析灰度图像中的灰度变化及测距图像中的测距值变化，分别求取各自图像中物体的特征点及特征边；然后，利用两配准图像之间的对应关系，求得所有特征点、面与多边形在三维测距图像中的三维表示；接着，通过分析三维测距图像中所测得的各候选平面上特定点与边处的曲率及法向，验证候选平面