Enhanced low-temperature activity and huimid-SO2 resistance of MnFe-based multi-oxide catalysts for the marine NH3-SCR reaction

Yi Wei,Wenhua Li,Qi Wang,Mengyu Liu,Peiyuan Liang,Lina Wang,Tianjun Sun 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.123 No.-

Several MnFe-based multi-metal oxides were synthesized as NH3-SCR catalysts by a simple coprecipitationmethod for abating NOx of marine diesel exhausts. The Co and Nb-doped MnFeCeAl catalysts exhibitNOx conversion over 90% and N2 selectivity above 95% at 180–270 C, especially the MnFeCeAlCo catalystscan inhibit nearly all sulfate species growth within 150 ppm humid-SO2 gases at 225 C. The structuralcharacterization results revealed that Co, Nb, Sm, and Sb doping can enhance interactions amongdifferent components and promote active component dispersion. Temperature programmed analysisindicated that the Co doping is not only more favorable for improving redox properties, but can alsoenhance the surface acidity, which are advantageous to improve the activity, N2 selectivity, andhumid-SO2 resistance. Moreover, the XPS results implied that the binding energy shift or the valence variationof the Sm, Sb, Nb, and Co species on catalyst surfaces are favored to raise the atomic ratios of highvalentMn species and surface adsorbed oxygen, which can promote the redox property significantly andfurther facilitate SCR activity. Accordingly, the excellent activity and humid-SO2 tolerance of theMnFeCeAlCo catalyst should attribute to its lower redox temperature, strong interaction between oxides,47.3% surface Mn4+/Mn3+ species, and 71.8% adsorbed oxygen, which provide a method for improving theSCR performances of MnFe-based catalysts with humid SO2 resistance.

Fault Diagnosis of Marine Turbocharger System Based on an Unsupervised Algorithm

Yi Wei,Hailong Liu,Gengxuan Chen,Jiawei Ye 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.3

The fault diagnosis of a marine turbocharger system is very crucial for realizing intelligent operation and maintenance in a big data analysis context. In order to improve the diagnostic rate of faults in engineering applications, in this paper, a new unsupervised machine learning algorithm, which is based on one-class support vector machine (OSVM), afnity propagation (AP) and Gaussian mixture model (GMM), called OAGFD is proposed for fault diagnosis. OSVM was frstly used to divide samples of marine turbocharger system into normal and fault samples, and only the fault samples are used in following steps to identify specifc fault types. The AP was adopted automatically to provide an initial value for expectation maximization, which can obtain the maximum value of iteration parameters. The GMM is used to classify faults of marine turbocharger system and output the fault diagnosis results. Finally, the OAGFD is validated by actual data. The experiment results show that OAGFD can quickly and accurately be trained. The OAGFD method can achieve higher identifcation accuracy for multi-faults of marine turbocharger system and takes on faster operation speed and stronger generalization ability than tradition methods. It is an efcient and unsupervised fault diagnosis technique and has both theoretical and practical value. This research provides a new method for automatic fault diagnosis of the marine turbocharger system.

Complete weight enumerators of some classes of linear codes with a few weights

Yiwei Liu,Zihui Liu 대한수학회 2018 대한수학회보 Vol.55 No.3

By choosing defining set properly, several classes of linear codes with a few weights over the finite field $\mathbb{F}_{p}$ are constructed for an odd prime $p$, and the complete weight enumerators of these classes of codes are determined.

Autonomous Blimp Control using Reinforcement Learning

Yiwei Liu,Zengxi Pan,David Stirling,Fazel Naghdy 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8

This paper presents a new approach for navigation control of an autonomous blimp using an intelligent reinforcement learning algorithm. Compared to the traditional model based control methods, this control strategy does not require a dynamic model of the blimp, which provides huge advantage in many practical situations where the blimp system model is either hard to acquire or too complicated to apply. As the blimp will acquire a range of the pilot skills through a learning and rewarding mechanism during actual navigation trials, it can automatically account for the environmental changes during the navigation. The simulation data generated from a Webots Robotics Simulator (WRS) demonstrate satisfactory results for planar steering motion control. Reinforcement learning based blimp control is shown to be a promising and effective solution for autonomous navigation tasks.

Rapid Predictions for Lower-Order Dynamics of Machine Tools Based on the Rigid Multipoint Constraints

Yiwei Ma,Yanling Tian,Xianping Liu 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.3

This study presents a rapid predicting method for lower-order dynamic performances of machine tools. Firstly, the governing equation of motion of the component substructure is obtained drawing on the dynamic condensation from the finite element analysis. Secondly, employing the rigid multipoint constraints at the joint and interface level, the improved reduced dynamic model of component substructures is formulated, resulting in a minimum set of generalized coordinates for external nodes. Then, utilizing the screw theory, the local stiffness mapping between joint and interfaces is illustrated. This is followed by merging the component and joint substructures, resulting in the reduced dynamic model of the entire machine tool. The proposed model is hugely efficient for predicting the distributions of dynamic performances within the entire workspace and guiding the optimal functional design under the framework of virtual machine tools. Finally, a comparison study on a box-in-box type precision horizontal machine tool shows that the lower-order dynamics predicted within the proposed approach have the same trend as those obtained by a complete order finite element model. The experimental modal analysis test shows that the errors of natural frequencies between the proposed model and experiments are lower than 15.61%, demonstrating the effectiveness and accuracy of the proposed model.

Between Enterprise and Compromise: Opportunities and Challenges for China’sDiplomacy after the Iraq War

Yiwei Wang 경남대학교 극동문제연구소 2004 ASIAN PERSPECTIVE Vol.28 No.3

To most Chinese, diplomacy is the art of compromise. In fact, from the perspective of the strong side, diplomacy is also the art of enterprise, in other words, diplomacy should take the initiative and the offensive. The Iraq war reveals that the United States will use military force when it cannot achieve its strategic goals, letting its diplomacy entirely serve the war effort. In this regard, U.S. diplomacy is often called a “pigeon with hawk’s paws” in China. China is rising, but cannot follow the American model, especially its model of diplomacy during war. How to express its enterprise and also its willingness to compromise is an urgent challenge that China will face in the next twenty-year “Strategic Opportunity Period.” The key is to achieve two basic goals for a country living in an anarchic world: security and development.

The End of Life

Yiwei Yuan,Siyu Cheng,Xiaowen Yan 한국콘텐츠학회 2015 ICCC International Digital Design Invitation Exhib Vol.2015 No.5

The Publicity and Promotion of Weifang Kate

Yiwei Yuan,Siyu Cheng,Xiaowen Yan 한국콘텐츠학회 2014 ICCC International Digital Design Invitation Exhib Vol.10 No.2

Dynamic Economic Dispatch and Control of a Stand-alone Microgrid in DongAo Island

Yiwei Ma,Ping Yang,Hongxia Guo,Yuewu Wang 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.4

A dynamic economic dispatch and control method is proposed to minimize the overall generating cost for a stand-alone microgrid in DongAo Island, which is integrated with wind turbine generator, solar PV, diesel generator, battery storage, the seawater desalination system and the conventional loads. A new dispatching strategy is presented based on the ranking of component generation costs and two different control modes, in which diesel generator and battery storage alternate to act as the master power source to follow system power fluctuation. The optimal models and GA-based optimization process are given to minimize the overall system generating cost subject to the corresponding constraints and the proposed dispatch strategy. The effectiveness of the proposed method is verified in the stand-alone microgrid in DongAo Island, and the results provide a feasible theoretical and technical basis for optimal energy management and operation control of stand-alone microgrid.

Modified Sub-aperture Stitching Algorithm using Image Sharpening and Particle Swarm Optimization

Yiwei Chen,Erlong Miao,Yongxin Sui,Huaijiang Yang 한국광학회 2014 Current Optics and Photonics Vol.18 No.4

This study proposes a modified sub-aperture stitching algorithm, which uses an image sharpening algorithm and particle swarm optimization to improve the stitching accuracy. In sub-aperture stitching interferometers with high positional accuracy, the high-frequency components of measurements are more important than the low-frequency components when compensating for position errors using a sub-aperture stitching algorithm. Thus we use image sharpening algorithms to strengthen the high-frequency components of measurements. When using image sharpening algorithms, sub-aperture stitching algorithms based on the least-squares method easily become trapped at locally optimal solutions. However, particle swarm optimization is less likely to become trapped at a locally optimal solution, thus we utilized this method to develop a more robust algorithm. The results of simulations showed that our algorithm compensated for position errors more effectively than the existing algorithm. An experimental comparison with full aperture-testing results demonstrated the validity of the new algorithm.