排序方式: 共有25条查询结果,搜索用时 15 毫秒
1.
2.
Ji Hoon Yang Min Hyung Yum Eun Jung Kim Myeung Hoi Kwon Cheol Woong Yang Ha-Jin Song Yong-Wan Jin 《Carbon》2006,44(11):2219-2223
Nitrogen molecules have been encapsulated into the central hollows of vertically aligned carbon nitride (CN) multiwalled nanofibers by dc plasma-enhanced chemical vapor deposition with C2H2, NH3, and N2 gases on a Ni/TiN/Si(1 0 0) substrate at 650 °C. X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectra showed the existence of nitrogen molecules in CN nanofibers. Elemental mapping images with electron energy loss spectroscopy of the CN nanofiber and catalyst metal, and optical emission spectroscopy spectra of the plasma showed the distribution of nitrogen atoms and molecules in the CN nanofiber, catalyst metal, and gaseous precursor, respectively. These studies showed that atomic nitrogen diffused into the catalytic metal particle because of the concentration gradient and then saturated at the bottom of the particle. Saturated nitrogen atom participated in the formation of the CN nanofiber wall but most of nitrogen was trapped in the central hollow of the nanofiber as molecules. 相似文献
3.
铑(Ⅲ)氯水配合物的制备及紫外可见光谱的研究 总被引:4,自引:0,他引:4
采用封管氯化的方法[1 ] ,制得铑的标准溶液。在一定条件下处理H3[RhCl6]溶液 ,获得K2 [Rh(H2 O)Cl5]、K3[RhCl6]和 [Rh(H2 O) 6]·(ClO4) 3种态。以K2 [Rh(H2 O)Cl5]和K3[RhCl6]为起始物 ,利用国产 71 7阴离子树脂 ,分别得到trans - [Rh(H2 O) 4 Cl2 ]+、cis- [Rh(H2 O) 4 Cl2 ]+、mer- [Rh(H2 O) 3Cl3]、fac- [Rh(H2 O) 3Cl3]和cis- [Rh(H2 O) 4 Cl4]- 种态。研究它们的紫外 -可见吸收光谱发现 ,随着配位内界水分子数的增加 ,其特征吸收峰表现为紫移。通过分析和研究它们的极性及特性吸收峰 ,提出了铑 (Ⅲ )氯水配合物新的鉴别方法。 相似文献
4.
脉冲噪声环境下的恒模盲均衡算法 总被引:2,自引:0,他引:2
α稳定分布噪声导致现有的基于梯度下降法的恒模盲均衡算法(SGD-CMA)失效.通过分析厚拖尾噪声对现有算法的影响,给出了2种改造算法,即韧性梯度下降恒模盲均衡算法(SGD-RCMA)和递归最小二乘恒模盲均衡算法(RLS-RCMA).仿真表明2种改造算法比传统的恒模盲均衡算法具有更好的适用性,不仅适用于高斯噪声环境而且适合于脉冲噪声环境.同时RLS-RCMA与SGD-RCMA相比具有更快的收敛速度和更好的码间干扰抑制能力. 相似文献
5.
Woo-Gon Kim Song-Nan Yin Yong-Wan Kim Woo-Seog Ryu 《Transactions of the Indian Institute of Metals》2010,63(2-3):145-150
Creep behaviours for Alloy 617, such as creep properties, oxidation and creep fracture morphologies were investigated by a series of creep tests with different stress levels at 1223 K. Creep constants of A, n, m, and C were obtained at 1223 K for Alloy 617. To accurately predict the long-term creep life (or strength) for Alloy 617, a multi constant method with two C in the Larson-Miller (LM) parameter was newly proposed instead of the conventional one with a unique C. The conventional method did not thoroughly match with the creep rupture data, and revealed an overestimation for the prediction of the long-term creep strength. On the other hand, the multi constant method revealed a good agreement with the creep rupture data, and this method was more accurate than the conventional one. The multi constant analysis can be used to accurately predict the long-term creep rupture life of Alloy 617 above 105 h for 1173 K, 1223 K and 1273 K. 相似文献
6.
CHEOL LAE ROH MOON NO LEE MYUNG JIN CHUNG 《International journal of systems science》2013,44(4):419-424
In this paper we propose a design method of an iterative learning controller (ILC) for a non-minimum phase (NMP) system by model-matching theory. The ILC consists of two learning filters acting on both the previous input signal and the previous error signal. To design the learning filters, we convert the convergence condition of the ILC into the model-matching problem and get the stable and proper learning filter by solving the Nevanlinna's algorithm. To show the usefulness of the proposed algorithm, some design examples are included. 相似文献
7.
Ozone (O3) was employed as an oxygen source for the atomic layer deposition (ALD) of titanium dioxide (TiO2) based on tetrakis-dimethyl-amido titanium (TDMAT). The effects of deposition temperature and O3 feeding time on the film growth kinetics and physical/chemical properties of the TiO2 films were investigated. Film growth was possible at as low as 75 °C, and the growth rate (thickness/cycles) of TiO2 was minimally affected by varying the temperatures at 150–225 °C. Moreover, saturated growth behavior on the O3 feeding time was observed at longer than 0.5 s. Higher temperatures tend to provide films with lower levels of carbon impurities. The film thickness increased linearly as the number of cycles increased. With thicker films and at higher deposition temperatures, surface roughening tended to increase. The as-deposited films were amorphous regardless of the substrate temperatures and there was no change of crystal phase even after annealing at temperatures of 400–600 °C. The films deposited in 0.5 mm holes with an aspect ratio of 3: 1 showed an excellent conformality. 相似文献
8.
In the immunoassay based on surface plasmon resonance (SPR) system, the signal enhancement was done by means of the conjugate of gold (Au) nanoparticle-antibody fragment. Antibody fragment was prepared for the improved immobilization based on Au-thiol interaction. Through the ellipsometric analysis on surface, the conjugation between Au and antibody fragment was performed in the oriented manner. The optimal fabrication conditions such as concentration and incubation time were determined for the constant size of the fabricated nanoparticle-antibody conjugate. Through the plot of SPR angle difference versus antigen concentration, the linear correlation was achieved, of which the detection limit was 100 fg/ml. 相似文献
9.
Do-Yoon Kim Jong-Hak Lee Prashant S. Alegaonkar In-Taek Han Yong-Wan Jin Kee-Won Kwon 《Thin solid films》2008,516(11):3534-3537
The photolithography process has generally been used for the making of catalyst layers used for the synthesis of CNTs due to its comparative ease. However, this method results in the formation of undesirable catalyst particles, which deteriorate the quality of the devices. Therefore, we tried to form a catalyst layer without using any lift-off or wet etching process, especially for the formation of carbon nanotube interconnects. After spin coating the samples, which were previously fabricated with several vias, with an iron-acetate solution, the catalyst layer was pulled down into the bottom of the holes through the force of gravity. We were able to remove the catalyst layer which was coated over undesirable areas, by TMAH (tetramethylammonium hydroxide, N(CH3)4OH) treatment. After the catalyst deposition process, we synthesized CNTs and observed them by scanning electron microscopy (SEM). 相似文献
10.
Woo-Gon Kim Song-Nan Yin Ji-Yeon Park Sung-Deok Hong Yong-Wan Kim 《Journal of Mechanical Science and Technology》2012,26(2):379-387
This paper presents an improved methodology for determining high-temperature tensile design strengths of Alloy 617, which
is regarded as one of main structural materials for very high temperature reactor (VHTR) system. In establishing time-independent
allowable stress values, an existing ASME standard procedure is preliminarily analyzed and their limitations are pointed out.
Then, an improved methodology, which has a consistent and quantifiable design margin at low and high temperatures for tensile
strengths, is proposed and compared with the ASME method. To find suitable curves of temperature trend to the tensile strength
data, three fitting methods are demonstrated, and a statistical technique is adopted for design use. The results will be utilized
to reasonably determine the tensile design strengths of Alloy 617 for application in the VHTR system. 相似文献