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Xiaobo Wang,Jie Zhou,Caojian Jiang,Jia Wang,Keting Gui,Hywel Rhys Thomas 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.12
Mn-Ce-Ti catalysts were prepared by different precursors (including manganese nitrate, manganese acetate, and manganese chloride) and used for selective catalytic reduction (SCR) of NO with ammonia. The relationships among the structure, physicochemical properties, and catalytic activity were explored by N2 adsorption/desorption, X-ray diffraction (XRD), H2-temperature programmed reduction (H2-TPR), NH3-temperature programmed desorption (NH3TPD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), scanning electron microprobe (SEM) and energy dispersive spectroscopy (EDS) techniques. The results show that the different Mn precursors play important roles in the catalytic activity. The Mn-Ce-Ti(N) catalyst synthesized by manganese nitrate precursor exhibits the best catalytic activity, while the Mn-Ce-Ti(C) and Mn-Ce-Ti(Cl) catalyst prepared by manganese acetate and manganese chloride, respectively, exhibit relatively low catalytic activity. The manganese nitrate precursor could promote the specific surface area and redox ability, enhance the amounts of Brønsted and Lewis acid sites, and enrich the surface active species such as Mn4+, Ce3+ and surface chemisorbed oxygen of the catalyst, all of which will contribute to the SCR performance. Moreover, the Mn-Ce-Ti(N) catalyst possesses highly dispersed and uniform surface active species, which will result in the optimal physicochemical properties and superior catalytic performance.
Design and Realization of Intelligent Question Answering System Based on Ontology
Xiaobo Wang,Wei Cui,Weicun Zhang 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
This paper presents an intelligent question answering system based on ontology, which adopts Chinese natural language processing technology to generate concise and appropriate answers to the student’"s questions. The accuracy and intelligence of the system are guaranteed through ontology based knowledge description, word segmentation, and question pattern recognition.
王?波(Wang Xiaobo) 전남대학교 글로벌디아스포라연구소 2014 전남대학교 세계한상문화연구단 국제학술회의 Vol.2014 No.11
President Xi Jinping"s visit to South Korea has sparked international concern about the issue of Korean peninsula. There are more discussion and thinking about whether North Korea is able to abandon nuclear program and seize the economic development opportunities and how to grasp the good development trend to avoid the existing and future development obstacle factors between China and South Korea. This article proposed China"s development path that we should concentrate on our own development, develop a good strategy in Northeast Asia, pay more attention to the United States factors and adhere to a flexible and pragmatic principles and take notice of the art of diplomacy and so on.
3.2-kW 9.7-GHz Polarization-maintaining Narrow-linewidth All-fiber Amplifier
Hang Liu,Yujun Feng,Xiaobo Yang,Yao Wang,Hongming Yu,Jue Wang,Wanjing Peng,Yanshan Wang,Yinhong Sun,Yi Ma,Qingsong Gao,Chun Tang 한국광학회 2024 Current Optics and Photonics Vol.8 No.1
We present a Yb-doped narrow-linewidth polarization-maintaining (PM) all-fiber amplifier that achieves a high mode-instability (MI) threshold, high output power, and 9.7-GHz spectral linewidth. Six wavelength-multiplexed laser diodes are used to pump this amplifier. First, we construct a high-power fiber amplifier based on a master oscillator-power amplifier (MOPA) configuration for experiments. Subsequently, we examine the MI threshold by individually pumping the amplifier with wavelengths of 976, 974, 981, 974, and 981 nm respectively. The experimental results demonstrate that the amplifier exhibits a high MI threshold (>3.5 kW) when pumped with a combination of wavelengths at 974 and 981 nm. Afterward, we inject an optimized phase-modulated seed with a nearly flat-top spectrum into this amplifier. Ultimately, laser output of 3.2 kW and 9.7 GHz are obtained.
Effect of Front and Rear Rotor Stages on Aeroelasticity in Multi-Stage Environment
Xiaobo Zhang,Yanrong Wang,Xianghua Jiang,Zhizhong Fu 한국항공우주학회 2019 International Journal of Aeronautical and Space Sc Vol.20 No.1
An energy method based on the mixing-plane model and phase lagged boundary condition has been developed to estimate the flutter characteristics of rotor blades in multi-stage environment. The effects of front and rear rotor stages on the aerodynamic damping of the rotor blades have been investigated using this method. The results show that the mixing-plane model enables to consider the averaging effect of the other stages on the aeroelasticity of the checked rotor blades without having to perform the unsteady full annual multi-stage (FAMS) flow computations. Comparing with the isolated rotor blade, the upstream and downstream rotor stages have a significant influence on the aeroelasticity of the rotor blade with altering the intensity and location of the shock wave and separation flow region on suction surface. It is worth to point out that the neighbor rotor stages reduce the effect of the inter-blade phase angle (IBPA) on the aerodynamic damping. Moreover, the impact of the rear rotor stage on aerodynamic damping of the rotor blade is more remarkable than that of the front one. Compared to the measured data, the capability of this method used in the aeroelasticity assessment of a multi-stage turbomachine has been validated. Furthermore, the relationship between the aerodynamic damping and the motion of the shock wave has been revealed, which can assist the compressor design.
Mistuning Effects on Aero-elastic Stability of Contra-Rotating Turbine Blades
Xiaobo Zhang,Yanrong Wang 한국항공우주학회 2019 International Journal of Aeronautical and Space Sc Vol.20 No.1
The aero-elasticity of contra-rotating turbine blades has been evaluated by employing the energy method and the aero-elastic eigenvalue method, which is different from the normal turbine blades with HPT wake impinging on the LPT directly. The effects of two different intentional mistuning patterns and random mistuning with standard deviation from 0.1 to 1% on aeroelastic stability of the low-pressure turbine (LPT) blades have been investigated by use of the eigenvaluemethod. Studies show that the best stabilized effect can be obtained with a specific distribution of mistuning amount for alternate and sinusoidal patterns. The random mistuning can improve the stability of tuned system with the increase of the standard deviation. But when the standard deviation is greater than 0.6%, the improving effect is invariable. For the mistuned system, the random mistuning decreases the stability of the intentional mistuned system and the optimal mistuning pattern has been changed. Additionally, when the standard deviation of the random mistuning is fixed, the mistuning amount has a more significant effect on the alternate mistuning than the sinusoidal mistuning.
Wang Wenjie,Han Zhenhua,Pei Jin,Pavesi Giorgio,Gong Xiaobo,Yuan Shouqi 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.1
To reduce the energy consumption of large centrifugal pumps, modified heuristic intelligent algorithms are used to directly optimize the diffuser of centrifugal pumps. Considering the hydraulic efficiency under the design condition as the optimization target, in this study, 14 geometric parameters such as the inlet diameter, outlet diameter, and leading and trailing vane angles of the diffuser are selected as design variables, and the modified particle swam optimization and gravitational search algorithm are used to directly search for optimization in the design space. The performance and loss of internal entropy production of the different models before and after optimization are compared and analyzed in detail. The results show that the global optimization ability of the modified algorithm is improved. The diffuser model changes from cylindrical to twisted, the vane wrap angle increases, and the thickness of the leading edge decreases. Under the design condition, the efficiency of modified particle swarm optimization algorithm solution is increased by 2.75% and modified gravitational search algorithm solution by 2.21%, while the power remains unchanged. Furthermore, the optimization solution has the largest lift efficiency improvement under part-load conditions. After optimization, the unstable flow in the model is improved and internal entropy production loss is reduced significantly. The interior of the diffuser is dominated by turbulent entropy production and direct entropy production under different operating conditions, and the wall entropy production accounts for the smallest proportion.
Xia Wang,Zongbao Li,Lichao Jia,Xiaobo Xing 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.10
A simple strategy to greatly increase the photocatalytic ability of nanocrystalline anatase has been put forward to fabricate efficient TiO2-based photocatalysts under visible irradiation. By surface modification with V ion, samples with different ratios were synthesized by using an incipient wetness impregnation method. The as-prepared specimens were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectroscopy. The photocatalytic activities were evaluated by using methylene blue degradations. Meanwhile, the optimized loading structure and electronic structures were calculated by using the density function theory (DFT). This work should provide a practical route to reasonably design and synthesize high-performance TiO2-based nanostructured photocatalysts.