排序方式: 共有73条查询结果,搜索用时 0 毫秒
1.
2.
分析了离心球铁管承口针孔及其成因。结果表明,来自树脂粘结剂中的N2,H2等气体是导致针孔的主要气体。氧化夹杂物作为气泡生核的核心,并使之生长。若铸件凝固速度等于气泡逸出速度,针孔生成。 相似文献
3.
The influence of pinholes on the chip on film (COF) in screen-printing was studied in this paper. Yield improvement is the most challenging part of COF manufacturing in view of its processing complexity, mainly in the screen-printing process. The process parameters such as ink capacity, origin control distance, angle of the squeezer, method of mixing, freshness of ink, speed of printing, and speed of scraper are considered to improve the pinholes. In Taguchi method, a two level orthogonal array is used to determine the signal-to-noise (S/N) ratio. Analysis of variance and the F-test values are used to determine the most significant process parameters affecting the pinholes. Confirmation analysis tests with the optimal levels of process parameters are carried out. The results of the experiment show that Taguchi method is a very suitable approach with regard to solving quality problems related to such pinholes. 相似文献
4.
基准离焦偏差控制技术 总被引:1,自引:0,他引:1
一种新的采用基准离焦信号的针孔调焦方案,用于激光直写的自动对焦子系统。通过在离焦曲线上提取参考离焦信号,建立基准离焦判据,它能容易地区分前离焦或后离焦,有效地克服了原有针孔调焦方案难于根据离焦信号来分辨离焦方向的弱点。借助微处理器和模拟电路实现了这一方案,并因此获得了均匀的1靘线宽的线条。 相似文献
5.
GAO Xiuli YANG Shunfang YU Yongli SHI Meiping ZHAO Lanxiang YE Jianding LU Jianying 《核技术(英文版)》2008,19(5):290-296
The study was to investigate the role of pinhole single photon emission computed tomography (SPECT), the human pulmonary adenocarcinoma bone-seeking metastasis cell line SPC-A-1BM was used. These cells form typical osteolytic bone metastases when inoculated into the arterial circulation of NIH-Beige-Nude-XD (BNX) mice v/a the left ventricle. In order to evaluate the irradiation impact of ^99mTc-MDP versus X-ray on cells growth, we used six groups of SPC-A-IBM cells in our imaging scheme and irradiated by various doses of ^99mTc-MDP (37, 74, 111, 370, 740 MBq) and X-ray(40 kV, 2 mA, 6 s) respectively. The cell's number of each group was well recorded in different exposure time( 4, 8, 12, 24, 48, 72, 96 hours ). After that, SPC-A-1BM cells (1×106) were inoculated into the mice via left ventricle. We compared the results obtained with those different doses of ^99mTc-MDP using pinhole SPECT and conventional X-ray skeletal surveys. The data show that the cell-survival number of 111 MBq group has insignificant difference with that of X-ray and the dose is adequate to have an ideal image. Besides, it is important that the chromosome of the cells in the group of 111 MBq showed no irradiation-related damages in our test. These results implied that ^99mTc-MDP pinhole SPECT may provide another way other than conventional X-ray skeletal surveys in detecting bone metastasis of pulmonary adenocarcinoma in BNX mice. 相似文献
6.
Experiments were carried out to investigate the corrosion behavior of epoxy-coated rebar(ECR) with pinhole defect(diameter in hundreds of microns) immersed in the uncarbonated/carbonated simulated pore solution(SPS) of seawater concrete. Corrosion behavior was analyzed by electrochemical impedance spectroscopy. The composition and morphology of corrosion products were characterized by X-ray diffraction, energy-dispersive spectrometry and scanning electron microscopy. Meanwhile, oxide film produced by preheating before spray coating was investigated by X-ray photoelectron spectroscopy and Mott–Schottky technology. Results indicated that corrosion behavior of ECR with pinhole defect exhibited three stages when immersed in the uncarbonated/carbonated SPS. In the initial stage, steel in defect was passivated when exposed in the uncarbonated SPS and corroded when exposed in the carbonated SPS, due to competitive adsorption between chloride and hydroxyl ions. In the second stage, the oxide film under coating reconstituted(the thickness and defects density decreasing) in the uncarbonated SPS, which was caused by the synergy between high hydroxide and chloride activity, while in the carbonated SPS, crevice corrosion happened under the coating around pinhole,because of the different oxygen concentrations cell at the coating/steel interface. In the third stage, localized corrosion occurred under the coating around the pinhole in the uncarbonated SPS, which was probably induced by ion diffusion at the nano-scale coating/steel interface. The corrosion products adjacent to the defects were re-oxidized from FeCl_2·4H_2O and Fe_2(OH)_3Cl to Fe_2O_3·H_2O, and the corrosion area was expanded outward in the carbonated SPS. 相似文献
7.
8.
Piotr Macech 《Thin solid films》2009,517(18):5399-5403
Nanoscopic defects present in ultrathin (~ 6 nm) silica films covalently attached to gold substrates through a gold oxide layer exhibit a voltammetric response consistent with a random array of ultramicroelectrodes. These pinholes can be passivated via electrochemical polymerization of phenol to create insulating poly(phenylene) oxide plugs as documented by atomic force microscopy and infrared reflectance-absorbance spectroscopy. Passivation of pinholes is ~ 99.5% complete after 550 voltammetric cycles of oxidative electropolymerization. 相似文献
9.
Stereovision is an effective technique to use a CCD video camera to determine the 3D position of a target object from two
or more simultaneous views of the scene. Camera calibration is a central issue in finding the position of objects in a stereovision
system. This is usually carried out by calibrating each camera independently, and then applying a geometric transformation
of the external parameters to find the geometry of the stereo setting. After calibration, the distance of various target objects
in the scene can be calculated with CCD video cameras, and recovering the 3D structure from 2D images becomes simpler. However,
the process of camera calibration is complicated. Based on the ideal pinhole model of a camera, we describe formulas to calculate
intrinsic parameters that specify the correct camera characteristics, and extrinsic parameters that describe the spatial relationship
between the camera and the world coordinate system. A simple camera calibration method for our CCD video cameras and corresponding
experiment results are also given.
This work was presented in part at the 7th International Symposium on Artificial Life and Robotics, Oita, Japan, January 16–18,
2002 相似文献
10.