超导磁体螺栓结合面低温振动特性研究

振动特性对于超导磁体的各类工程应用具有重要意义,螺栓法兰盘连接是超导磁体系统的一种常见的支撑结构类型,然而螺栓结合面在低温条件下振动特性的相关研究目前尚少见报道.本研究中设计加工了简化的连接结构,在室温和液氮温度对其螺栓结合面进行振动特性的测试分析.接下来,采用集中质量法进行建模,并利用振型、频率与质量矩阵、刚度矩阵的关系求解了不同螺栓预紧力情况下的刚度矩阵,得到了系统总刚度和结合面刚度.使用上述方法对振动测量数据计算发现,该结构的系统总刚度与结合面刚度都随着预紧力增大而增大,同时液氮低温条件可使系统总刚度和结合面刚度进一步增大.     

振镜法测量等离子体离子温度

 离子温度是托卡马克等离子体一个重要参数，介绍了一套振镜扫描装置，该装置主要由0.5m单色仪和安装在出射狭缝前的振动的石英镜片组成，时间分辨率小于10ms，系统测量误差小于20eV。测量了HT-6M托卡马克CV(227.1nm)谱线的线形，并由谱线的多普勒展宽得出欧姆加热和离子回旋共振加热（ICRH）下的离子温度，结果表明ICRH期间离子温度由200eV升高到300eV。这套装置广泛应用在中小型托卡马克上。     

Spatial arrangement of the structural elements ofvocal fold layers: An adjustment to the vibration process

It is well established that the multilayered structure of the vocal fold is highly adjusted to the requirements of the vibration process during phonation. There is also some partial data indicating that the spatial arrangement of each vocal fold layer corresponds to the functional requirements, and thus facilitate the phonation process. Nevertheless, all reports on the spatial arrangement of the vocal fold structures deal only with an individual element of the vocal fold histologic structure. The present study encompasses the spatial histologic analysis of all major elements of the vocal fold layers. It was demonstrated that the vocal fold epithelial cells, the connective and muscle fibers, and even the blood vessels run parallel to the vocal fold free edge, which indicates a high adjustment to the phonation requirements and the vibration process.     

Investigation of dynamic displacements of lithographic press rubber roller by time average geometric moiré

Geometric moiré fringe formation method is a classical well-established experimental technique with numerous practical applications. This paper proposes the application of time-average geometric moiré analysis for the determination of dynamic displacements of the lithographic press rubber roller. This optical measurement technique is a natural extension of double-exposure geometric moiré for the identification of dynamic displacements of vibrating elastic structures. Experimental investigations prove the validity and effective practical applicability of the method.     

Measurement of modal damping by electronic speckle shearing interferometry

A time-average electronic speckle shearing interferometer (ESSI) has been used for modal damping measurement. This is effected by a new fringe enhancement technique. The damping factor of a cantilever measured by using this technique agrees well with the value measured by using the accelerometer method. The study shows that time-average speckle interferometry can be used as a convenient tool for modal damping measurement.     

Infrasonic sound pressure in dwellings at the Helmholtz resonance actuated by environmental noise and vibration

The Helmholtz resonator effect of a room with an open window or ventilation duct has been studied theoretically and experimentally. The effect results in a sound pressure buildup at infrasonic frequencies. For comparison, the frequencies of the standing-wave room resonances are above the infrasonic range for residential dwellings. The relations between the sound pressure inside a room and outside (environmental) sound pressure or vibration acceleration have been calculated for the third-octave frequency band incorporating the Helmholtz resonance frequency. The experiment on a small-scale model illustrated the Helmholtz resonator effect caused by environmental vibration.     

高层住宅水泵房噪声与振动治理

为解决高层居民住宅生活用水和消防用水，一般均设置水泵房，若水泵房设计安装不当，将成为扰民的噪声源和振动源。本文以上海几栋高层住宅水泵房为例，通过采取隔振，软联接等措施，有效地控制了振动传递，降低了噪声，达到了环保标准要求。     

Noise reduction efforts for the ALS infrared beamlines

The quality of infrared microscopy and spectroscopy data collected at synchrotron based sources is strongly dependent on signal-to-noise. We have successfully identified and suppressed several noise sources affecting beamlines 1.4.2, 1.4.3, and 1.4.4 at the advanced light source (ALS), resulting in a significant increase in the quality of FTIR spectra obtained. In this paper, we present our methods of noise source analysis, the negative effect of noise on the infrared beam quality, and the techniques used to reduce the noise. These include reducing the phase noise in the storage ring radio-frequency (RF) system, installing an active mirror feedback system, analyzing and changing physical mounts to better isolate portions of the beamline optics from low-frequency environmental noise, and modifying the input signals to the main ALS RF system. We also discuss the relationship between electron beam energy oscillations at a point of dispersion and infrared beamline noise.     

气相色谱法测定气固表面的吸附停留时间

提出了一个用气相色谱测定气体在固体表面上吸附停留时间的方法. 经推导, 得到了测定公式.用八种烷烃及苯在硅胶上的吸附实验数据进行验证和研究, 得到了满意的结果.     

Equations of Mathematical Physics and Compositions of Brownian and Cauchy Processes

We consider different types of processes obtained by composing Brownian motion B(t), fractional Brownian motion B _H (t) and Cauchy processes C(t) in different manners. We study also multidimensional iterated processes in ? ^d , like, for example, (B ₁(|C(t)|),…, B _d (|C(t)|)) and (C ₁(|C(t)|),…, C _d (|C(t)|)), deriving the corresponding partial differential equations satisfied by their joint distribution. We show that many important partial differential equations, like wave equation, equation of vibration of rods, higher-order heat equation, are satisfied by the laws of the iterated processes considered in the work. Similarly, we prove that some processes like C(|B ₁(|B ₂(…|B _n+1(t)|…)|)|) are governed by fractional diffusion equations.