Methane (CH4) concentration distribution in a semiconductor process chamber was controlled using the measurement of computed tomography-tunable diode laser absorption spectroscopy (CT-TDLAS) and the ...feedback control toward the feeding CH4 concentrations and flow rates. CH4 diluted with nitrogen was fed into the chamber through a shower head having three separate and concentric areas. Thirty-two laser paths were configured in the chamber to collect the infrared absorption spectra for the CT-TDLAS measurement. The computed tomography calculation using the 32 spectra reconstructed the two-dimensional CH4 concentration distribution in the chamber. The measured concentration distribution was updated once per second. Based on the measured concentration distribution, the feedback control algorithm determined the feeding CH4 concentration and flow rate of each shower head area. In this work, we set the target distribution as a ring shape. In the control algorithm, first the feeding CH4 flow rate of each shower head area was adjusted to match the concentration peak radius in the measured distribution to the radius in the target distribution. Then, the feeding CH4 concentration of each area was adjusted in sequence to match the measured average concentration of each area to the corresponding concentration in the target distribution. The algorithm worked successfully, and the concentration distribution reached the target distribution. The extension of the application and its limitations were also discussed.
We performed in-situ monitoring of bis-cyclopentadienyl magnesium (Cp2Mg) vapor pressure supplied into a metal-organic vapor phase epitaxy reactor. As a light source we adopted a quantum cascade ...laser (QCL) of 12.9 m, which is the wavelength of Cp2Mg infrared absorption. We directly configured a laser path in the reactor to construct the Cp2Mg in-situ monitoring system. We streamed Cp2Mg and measured the vapor pressure in the reactor to evaluate it and its saturation and purge times in comparison with their calculated values which were determined from the measured values in the supply line. Next, we streamed Cp2Mg and other gas species used in gallium-nitride processes one by one to investigate their saturation times with the same QCL. Characteristic features of Cp2Mg such as the largest saturation time ratio and its large fluctuation were observed. These results indicate the importance of Cp2Mg in-situ monitoring in the reactor.
A CASE OF GIANT FIBROUS BREAST TUMOR GOTO, Ryoichi; MINAMI, Masakazu; TAKAHASHI, Masato ...
Nihon Rinsho Geka Gakkai Zasshi (Journal of Japan Surgical Association),
2002, Letnik:
63, Številka:
7
Journal Article
Odprti dostop
A premenopausal 49-year-old, woman, who noted a mass in her right breast, 7 years earlier was admitted when the tumor occupied her entire right breast. Fine-needle aspiration cytology showed no ...epithelial cells. Core needle biopsy showed proliferated fibrous connective tissue. We could not distinguish this tumor from a phylloides tumor so we conducted a simple mastectomy, the cut surface of the tumor was whitish, solid, homogeneous, cyst-free and about 15cm at its greatest diameter. Microscopically, the lesion consisted of collagenous stroma with markedly decreased or absent ductal and lobular elements, which we diagnosed as a fibrous tumor. The tumor was the largest among previously reported fibrous tumors.
A new method for simple robust control of multimodes of vibration of flexible structures is proposed. Although robust control theories such as H∞ theory are useful for controlling systems with ...unknown factors and parameter variations, they are not effective for controlling multimodes of vibration of flexible structures. The proposed method combines the suboptimum control theory and two kinds of filtering technique for reducing the number of sensors and preventing spillover of neglected higher modes of vibration. Therefore, the method is called the filtered suboptimal control method. The effectiveness of the method is demonstrated by showing that the first five modes of vibration of a model structure of large bridge tower are well controlled without spillover of neglected higher modes.
The vibration of towers of suspended bridges due to strong wind has been of great concern to scientists and engineers. In this study, attention is given to the vibration control of a tall bridge ...tower under construction. An active control method is presented based on the lumped model of the bridge tower and the suboptimal control theory. Since the dynamic parameters of the tower differ under different phases of construction, it is necessary to reevaluate the corresponding model, nevertheless, the control strategy is maintained. Three typical construction phases of a bridge tower are considered in this paper. The modeling method and results of the simulation control are presented to illustrate the validity of the proposed method.
This report deals with a method for the natural vibration analysis of high speed semi-submergeble catamaran which is made up of two cylindrical lower hulls, struts and upper deck. The exact ...evaluation of added mass of water is inevitable to estimate the natural frequencies for such a structure, because vibration modes are fully three dimensional and are much different from the ordinary ship hull vibration modes. Therefore the authors present here a method to compose a three dimensional added mass matrix by use of J factor, which is well known as a three dimensional correction factor. The exciting tests of the experimental model were carried out, and the measured results showed a fairy good agreement with the calculated values obtained by the proposed method.
A fundamental study on vibration characteristics of the air cushion craft was performed taking dynamic behavior of the pneumatic seal structure into consideration. A linearized mathematical model of ...the air cushion craft dynamics was derived. The effect of each parameter on the dynamic stability was obtained analytically and experimentally from the view point of negative resistance excitation system. The conclusions are as follows : 1) The dynamic stability of pneumatic seal structural vibration depends on the air transmission line characteristics and the seal configuration. The effects of these parameters on the stability criteria of the system are numerically examined. 2) In the model test, the self excited vibration caused by the instability of the pneumatic seal system was observed in some range of the inlet area of fan and feedhole area in the air chamber. 3) The calculated fundamental natural frequency for air cushion craft model agreed very well with model test results. The stable region varied in accordance with feedhole area in the model test, and a similar tendencies were also observed in the numerical analysis. A further study is necessary to discuss the difference between model test results and numerical analysis results.
PDF
