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排序方式: 共有173条查询结果,搜索用时 44 毫秒
1.
Kyu-Hyun Han Kyong-Won Seo Dae-Hyun Hwang Soon Heung Chang 《Nuclear Engineering and Design》2006,236(2):164-178
Gas-cooled reactors have been highlighted as a promising option for next generation reactor technology. A thermal hydraulic analysis code for gas-cooled reactors has been developed with a heat transfer model of a block element, which is solved implicitly with the helium energy equation. Validation was carried out through comparison with both experimental and analytical results. A computation module for annular fuel rods has been coupled to the code for comparative analyses of an annular fuel-based block element. At normal operation, the annular fuel shows 80 °C lower peak temperature than the solid fuel for the same power in Japan's high temperature engineering test reactor (HTTR), even though the pressure drop is higher in the annular fuel. 相似文献
2.
Liquid-phase catalytic degradation of waste polyolefinic polymers (HDPE, LDPE, PP) over spent fluid catalytic cracking (FCC)
catalyst was carried out at atmospheric pressure with a stirred semi-batch operation. The effect of experimental variables,
such as catalyst amount, reaction temperature, plastic types and weight ratio of mixed plastic on the yield and accumulative
amount distribution of liquid product for catalytic degradation was investigated. The initial rate of catalytic degradation
of waste HDPE was linearly increased with catalyst amount (4-12 wt%), while that was exponentially increased with reaction
temperature (350-430 ‡C). Spent FCC catalyst in the liquid-phase catalytic degradation of polymer was not deactivated fast.
The product distribution from catalytic degradation using spent FCC catalyst strongly depended on the plastic type. The catalytic
degradation of mixed plastic (HDPE: LDPE: PP: PS=3: 2: 3: 1) showed lower degradation temperature by about 20 ‡C than that
of pure HDPE. 相似文献
3.
4.
Neural networks are widely used in many applications including astronomical physics,image processing, recognition, robotics, and automated target tracking, etc. Their ability to approximate arbitrary functions is the main reason for this popularity. In this paper, we discuss the constructive approximation on the whole real line by a neural networks with a sigmoidal activation function and a fixed weight. Using the convolution method, we show neural network approximation with a fixed weight to a continuous function on a compact interval. Also, we demonstrate a computational work that shows good agreement with theory. 相似文献
5.
Il-Rock Oh Man-Ki Kim Yong-Woo Jo Dae-Hyun Kim Young-Don Choi Young-June Moon Jin-Teak Chung 《Journal of Mechanical Science and Technology》2012,26(12):3833-3841
We conducted a computational analysis to better understand the coherent flow structure that arises when the rotation of a disk drive generates flow-induced noise. We set the flow domain to be similar to the actual shape of the flow in Blu-ray disks and examined the phenomena of vortex generation and shedding at the disk edge, focusing on the source of the noise. Our results showed that disk edge vortex shedding was the primary cause of disk-drive-flow-induced noise; therefore, we investigated the technique of lowering the intensity of a disk edge vortex to reduce this noise. We attached concentric projections onto the cover of the disk to suppress the flow returning to the center of the disk through the gap between the disk and cover. Noise induced by disk rotation was reduced by 2.68 dB at the optimal setting: projections 0.002 m wide and 0.006 m width between the projections (and thus a ratio of 1: 3). 相似文献
6.
Bombi Lee Jinhee Park Sunoh Kwon Mijung Yeom Bongjun Sur Insop Shim Hyejung Lee Suk Hoo Yoon Dong-Myong Jeong Dae-Hyun Hahm 《Food science and biotechnology》2012,21(3):723-729
The aim of this study was to investigate the effects of sowthistle (Ixeris dentata, IXD) on development and expression of nicotine-induced locomotor sensitization and underlying neuronal activation reflected by c-Fos expression in rats. Rats were pretreated with IXD 30 min before a daily injection of nicotine during an 8-day development phase and then challenged with nicotine after a 6-day withdrawal period. In another set of experiments, same IXD doses were administered once 30 min before nicotine challenge. Daily IXD treatment during development phase was not effective in blocking nicotine-induced locomotor sensitization in rats. However, a single IXD treatment after the development and withdrawal periods of nicotine sensitization significantly alleviated sensitized locomotor behavior on day 15. These behavioral results were coincident with significant inhibition of nicotineinduced c-Fos expression in the nucleus accumbens. These results indicated that IXD pretreatment significantly blocked the expression, but not the development of nicotine-induced locomotor sensitization in rats. 相似文献
7.
Jinu Park Sang-Bum Kim Jae-Mok Ha Myung-Soo Kim Hong-Soo Park Hyun-Sik Hahm 《Korean Journal of Chemical Engineering》2001,18(4):468-474
The crystallization of the [Ga]-MFI was investigated as a function of synthesis time under atmospheric pressure. The molar
composition of the reactants was 100SiO2-Ga2O3-llNa2O-llTPABr-3500H2O. The crystallinity of the [Ga]-MFT was examined by using several analytical instruments, such as XRD, XPS, XRF, FT-IR, solid-statemas-NMR, DTG/DTA, and SEM. The [Ga]-MFI was successfully synthesized under atmospheric pressure at 97 ‡C in 72 h. It was found that
the nucleation of the [Ga]-MFI took a quite long time, but the crystallization took place very fast. It is supposed that nucleation
is the rate-controlling step in the [Ga]-MFI synthesis under atmospheric pressure. Consequently, if the induction period of
the nucleation can be shortened, it would be possible to synthesize the [Ga]-MFI commercially under atmospheric pressure. 相似文献
8.
Dae-Hyun Hwang Se-Young Chun Keung-Koo Kim Chung-Chan Lee 《Nuclear Engineering and Design》2007,237(4):369-376
The characteristics of Critical Heat Flux (CHF) were investigated for a square array of rod bundles which could possibly be loaded into an integral-type advanced light water reactor. The parametric effects of the mass velocity and the unheated rod were examined by conducting CHF experiments with 5 × 5 test bundles in a Freon-loop. The influence of a cold wall on the CHF was interpreted by introducing a simple phenomenological model which accounts for the influence of a thermal mixing inside the boiling channel. A local parameter CHF correlation applicable to an integral-type reactor was developed from the CHF data base for square-arrayed rod bundles. The local thermal–hydraulic conditions calculated by the subchannel analysis code MATRA were used for the optimization of the correlation coefficients. Correction factors for the low mass velocity, spacer grids, and the non-uniform axial power shapes have been devised which reflected the results of the data assessment and the experimental observations. As a result of the thermal margin evaluation at steady state conditions, it was revealed that the integral-type reactor core has a greater DNBR margin than a typical 1000 MWe PWR core. 相似文献
9.
Marc Delcroix Keisuke Kinoshita Tomohiro Nakatani Shoko Araki Atsunori Ogawa Takaaki Hori Shinji Watanabe Masakiyo Fujimoto Takuya Yoshioka Takanobu Oba Yotaro Kubo Mehrez Souden Seong-Jun Hahm Atsushi Nakamura 《Computer Speech and Language》2013,27(3):851-873
Research on noise robust speech recognition has mainly focused on dealing with relatively stationary noise that may differ from the noise conditions in most living environments. In this paper, we introduce a recognition system that can recognize speech in the presence of multiple rapidly time-varying noise sources as found in a typical family living room. To deal with such severe noise conditions, our recognition system exploits all available information about speech and noise; that is spatial (directional), spectral and temporal information. This is realized with a model-based speech enhancement pre-processor, which consists of two complementary elements, a multi-channel speech–noise separation method that exploits spatial and spectral information, followed by a single channel enhancement algorithm that uses the long-term temporal characteristics of speech obtained from clean speech examples. Moreover, to compensate for any mismatch that may remain between the enhanced speech and the acoustic model, our system employs an adaptation technique that combines conventional maximum likelihood linear regression with the dynamic adaptive compensation of the variance of the Gaussians of the acoustic model. Our proposed system approaches human performance levels by greatly improving the audible quality of speech and substantially improving the keyword recognition accuracy. 相似文献
10.
Jinu Park Sang-Bum Kim Jae-Mok Ha Hong-Soo Park Hyun-Sik Hahm 《Catalysis Letters》2001,75(1-2):125-130
The crystallization of [Ga]-MFI was investigated as a function of synthesis time under atmospheric pressure. The molar composition of the reactants was 100SiO2–Ga2O3–11Na2O–11TPABr–3500H2O. The crystallinity of [Ga]-MFI was examined using several analytical instruments, such as XRD, XPS, XRF, FT-IR, solid state MAS-NMR, and DTG/DTA. [Ga]-MFI was successfully synthesized under atmospheric pressure at 97°C in 72 h. It was found that the nucleation of [Ga]-MFI took quite a long time, but the crystallization took place very fast. It is supposed that the nucleation is the rate-controlling step in [Ga]-MFI synthesis under atmospheric pressure. Consequently, if the induction period of the nucleation can be shortened, it would be possible to synthesize [Ga]-MFI commercially under atmospheric pressure. 相似文献