检索结果-内蒙古大学图书馆

CeO 2 quantum dots/LZU1 Z-scheme heterojunction for photocatalytic selective oxidative coupling of benzylamines

Journal of Rare Earths 2024年

作者： Yezi Hu Rusong Sang Feng Chu Zewen Shen Guixia Zhao Junrong Yue Xiubing Huang MOE Key Laboratory of Resources and Environmental System Optimization College of Environmental Science and Engineering North China Electric Power University Beijing 102206 China State Key Laboratory of Multi Phase Complex System Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China Beijing Advanced Innovation Center for Materials Genome Engineering Beijing Key Laboratory of Function Materials for Molecule & Structure Construction School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Imines play a pivotal role as multifunctional intermediates in pharmaceutical and biological applications, and their selective synthesis under mild conditions has attracted increasing interest. In this study, a covalent-organic frameworks (COFs) modified with CeO 2 quantum dots (QDs) were prepared through a simple chemical reaction using LZU1 COFs and Ce(NO 3 ) 3 ·6H 2 O serving as precursors. The optimized 5CeO 2 QDs@LZU1 decorated with about 3.9 wt% CeO 2 QDs demonstrates excellent performance in the photocatalytic selective oxidative of amines in visible light conditions, achieving nearly 100% benzylamine conversion and over 99% imine selectivity within 6 h, which is significantly superior to that of pure LZU1 and CeO 2 . The remarkable enhancement in activity is mainly attributed to the fact that the interaction between CeO 2 QDs and LZU1 COF in 5CeO 2 QDs@LZU1 improves the visible light response and concurrently promotes the separation efficiency of photogenerated e ‒ and h + pairs. Broad substrate scope also provides a prospect for the industrial synthesis of various imines. Our findings not only expand the application range of COFs by incorporating QDs but also lay the groundwork for their further rational design and optimization.

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Stability and energetics of two-dimensional surface crystals in liquid AuSi thin films and nanoscale droplets

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Physical Review Materials 2021年第7期5卷 074003-074003页

作者： Hailong Wang Mengyuan Wang Alireza Shahabi Alain Karma Moneesh Upmanyu CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics CAS Center for Excellence in Complex System Mechanics University of Science and Technology of China Hefei Anhui 230027 China Group for Simulation and Theory of Atomic-Scale Material Phenomena (stAMP) Department of Mechanical and Industrial Engineering Northeastern University Boston Massachusetts 02115 USA Department of Physics Northeastern University Boston Massachusetts 02115 USA

We employ atomic-scale computational frameworks to study the surface crystallization in AuSi films and droplets as a function of composition, temperature, and size. Above the melting point, the surfaces of both thin films and droplets undergo a first-order transition from a two-dimensional (2D) Au2Si crystalline phase to a laterally disordered yet stratified layer. The thin film surfaces exhibit an effective surface tension that increases with temperature and decreases with Si concentration, while for droplets in the size range 10–30 nm, the bulk Laplace pressure alters the surface segregation as it occurs with respect to a strained bulk. Above the transition, the size effect on the surface tension due to the stratified surface layer is small, while the crystalline surface layer below the transition is strained and composed of 2D crystallites separated by extended grain boundary scars that lead to large fluctuations in its energetics. As a specific application, all-atom simulations of AuSi droplets on Si(111) substrate subject to Si surface flux show that the supersaturation dependent surface tension destabilizes the contact line via formation of a precursor wetting film on the solid-vapor interface and has ramifications for size selection during droplet-catalyzed routes for nanowire growth. Our study sheds light on the interplay between stability and energetics of surfaces in this unique class of binary alloys and offers pathways for exploiting their surface structure for varied applications such as catalytic nanocrystal growth, dealloying, and polymer crystallization.

关键词： Crystal forms Growth Interface & surface thermodynamics Nanocrystals Structural phase transition 2-dimensional systems Surfaces Molecular dynamics

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Identifying Key Node with Motif-Based PageRank on Acupoint-Disease Network

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Evidence-based complementary and alternative medicine : eCAM 2023年第1期2023卷 6101751页

作者： Xuelong Yu Xiao Liu Li Luo Hai Zhao Engineering Research Center of Security Technology of Complex Network System School of Computer Science and Engineering Northeastern University Shenyang 110169 China. Beijing PERCENT Technology Group Co. Ltd. Beijing 100096 China. School of Computer Communication Lanzhou University of Technology Lanzhou 730050 China.

Existing research combines acupuncture theory with network science and proposes a new paradigm for the study of acupoint selection patterns-a key acupoint mining algorithm based on acupoint networks. However, the basic idea of this study for finding key acupoints is based on binary acupoint synergy relationships, which ignores the higher-order synergy among multiple acupoints and does not truly reflect the implicit patterns of each acupoint among meridian systems. Moreover, the mining results assessment method, which this new paradigm involves, does not have wide applicability and universality. In this paper, with the introduction of higher-order interactions between multiple acupoints, a high-specificity key acupoint mining algorithm based on 3-node motif is proposed in the acupoint-disease network (ADN). In response to the narrow applicability of the new research paradigm involving the evaluation of algorithms' measures, new and widely applicable and universal evaluation criteria are introduced in terms of resolution, network loss, and accuracy, respectively. Based on the principles of acupoint selection involved in acupuncture clinics in Chinese medicine, the acupoints involved in the data were divided into a total of 19 regions according to their distribution characteristics. From these 19 regions, we selected the key acupoints that have a large impact on the global network. Finally, we compared this algorithm with five other acupoint importance assessment algorithms in terms of resolution, network loss, and accuracy, respectively. The comprehensive results show that the algorithm identifies key acupoints with an accuracy of 63%, which is 14% to 21% higher than other existing methods. The key acupoints identified by the algorithm have a significant disruptive effect on the connectivity of the network, indicating that the key acupoints are at the core of the acupoint-disease network topology. They have a significant propagation influence on other acupoints, which

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Design and polarization scattering characteristics of L-shape reflector

TechRxiv

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TechRxiv 2020年

作者： Bai, Xiaokai Wang, ZhanLing Huang, Jiankai Pang, Chen Li, Jianbing Li, Yongzhen State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and Engineering National University of Defense Technology Hunan Changsha410073 China

This paper presents a new L-shape reflector to enhance the cross-polarization radar cross section (RCS). Cross-polarization component can increase the jamming effect against the polarization radars. Such L-shape reflectors can also be used as radar tags in cars, books and so on for radar target detection. By bending the structure of traditional dipole reflector to L shape, the direction of surface current is changed, which produces the cross-polarization component. We have simulated L-shape reflector with different lengths of branches in X-band. Compared with the scattering characteristics of traditional dipole reflector, the linear depolarization ratio (LDRvh ) of the L-shape reflector can be easily controlled by changing the length of two branches. © 2020, CC BY.

关键词： Radar cross section

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Regularized densely-connected pyramid network for salient instance segmentation

arXiv

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arXiv 2020年

作者： Wu, Yu-Huan Liu, Yun Zhang, Le Gao, Wang Cheng, Ming-Ming TKLNDST College of Computer Science Nankai University Tianjin300350 China ETH Zurich Switzerland School of Information and Communication Engineering University of Electronic Science and Technology of China China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing China

Much of the recent efforts on salient object detection (SOD) have been devoted to producing accurate saliency maps without being aware of their instance labels. To this end, we propose a new pipeline for end-to-end salient instance segmentation (SIS) that predicts a class-agnostic mask for each detected salient instance. To better use the rich feature hierarchies in deep networks and enhance the side predictions, we propose the regularized dense connections, which attentively promote informative features and suppress non-informative ones from all feature pyramids. A novel multi-level RoIAlign based decoder is introduced to adaptively aggregate multi-level features for better mask predictions. Such strategies can be well-encapsulated into the Mask R-CNN pipeline. Extensive experiments on popular benchmarks demonstrate that our design significantly outperforms existing state-of-the-art competitors by 6.3% (58.6% vs. 52.3%) in terms of the AP metric. The code is available at https://***/yuhuan-wu/RDPNet. © 2020, CC BY-NC-ND.

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Demand estimation of water resources based on algorithm comparison

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International Journal of Wireless and Mobile Computing 2019年第2期16卷 110-116页

作者： Wang, Junyan Zhang, Jiangjiang Cai, Xingjuan Ma, Yanyan Jiangxi Province Key Laboratory of Water Information Cooperative Sensing and Intelligent Processing Nanchang Institute of Technology Nanchang330099 China Complex System and Computational Intelligence Laboratory TaiYuan University of Science and Technology Taiyuan003024 China Shanxi Cloud Era TISCO Information Automation Technology Co. Ltd. Taiyuan030003 China

Water is the source of life and the correct assessment of water resources is an important prerequisite for the rational utilisation of water resources. In this paper, water resources are evaluated and predicted by three different algorithms, including Bat Algorithm (BA), Particle Swarm Optimisation (PSO) and Pigeon-Inspired Optimisation (PIO). Comparing the errors of water resources assessed for the three algorithms, we select an algorithm of the minimum error to predict the future water demand. In the experiments, firstly, the water data from 2003 to 2012 are used to find the optimal weights of the models. Then, the weight factor is combined with the given model to gain the error between predicted value and the remaining data (2013–2015). Finally, the simulation results show that PIO algorithm has a better performance compared with the BA and PSO algorithms. Copyright © 2019 Inderscience Enterprises Ltd.

关键词： Water resources

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Optimal Terrain Following Trajectory Regeneration Using Linear Gauss Pseudo-Spectral Method

Optimal Terrain Following Trajectory Regeneration Using Line...

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2019 IEEE International Conference on Unmanned systems, ICUS 2019

作者： Feng, Yijun Chen, Wanchun Yang, Liang Wei, Donghui Beihang University School of Astronautics Beijing China Beijing Electro-Mechanical Engineering Institute Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing China

ISBN: (纸本)9781728137926

A numerical method for two-dimensional terrain following optimal trajectory regeneration is proposed in this paper, which corrects the planned optimal trajectory to avoid collision with previously unknown obstacles. The neighboring extremal problem is established near the optimal terrain following trajectory, which can be regarded as a two-point boundary-value problem (TPBVP) and solved using Linear Gauss Pseudo-Spectral (LGP) method. Compared with the classical backward sweep method for solving TPBVPs, LGP method is much faster in obtaining approximate results. Numerical simulations are provided to validate the effectiveness and demonstrate the features of the problem. © 2019 IEEE.

关键词： Numerical methods

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Radar Signal Recognition Based on Squeeze-and-Excitation Networks

Radar Signal Recognition Based on Squeeze-and-Excitation Net...

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2019 IEEE International Conference on Signal, Information and Data Processing, ICSIDP 2019

作者： Qu, Qizhe Wei, Shunjun Su, Hao Wang, Mou Shi, Jun Hao, Xiaojun State Key Lab. of Complex Electromagnetic Environment Effects on Electronics and Information System Luoyang471003 China University of Electronic Science and Technology of China Chengdu611731 China

ISBN: (纸本)9781728123455

Classification and recognition of radar signals is an important part of modern warfare. Traditional radar signal recognition method based on the pulse description word may be not suitable for the complex electromagnetic environment. In this paper, a novel radar signal recognition method based on Squeeze-and-Excitation networks is proposed. Firstly, time-domain, frequency-domain and time-frequency-domain features of five kinds of radar signals are transformed into images. Then the images are classified by convolutional neural networks and output the result of each domain. Finally, the results of the three domains are combined to obtain the correct identification results. And the recognition effects of three different modules are compared. The experiments prove the efficiency of our method, especially on different SNR condition and center frequency. And confusion matrixes demonstrate that under the low SNR condition, our method still has a good recognition effect and are better than traditional radar signal recognition method based on PDW. © 2019 IEEE.

关键词： Convolution

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Monocular visual based obstacle distance estimation method for ultra-low altitude flight

Monocular visual based obstacle distance estimation method f...

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2019 IEEE International Conference on Unmanned systems, ICUS 2019

作者： Cheng, Jin Wei, Donghui Chen, Wanchun Gao, Wang Beijing Electro-Mechanical Engineering Institute Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing China Beihang University School of Astronautics Beijing China

ISBN: (纸本)9781728137926

This paper focuses on the problem of ultra-low-altitude flight obstacle distance estimation for monocular vision-assisted aircraft. First, the basic error model of distance estimation using sequence images is derived and the phenomenon of "epipole dead zone" is revealed. Then the distance estimation algorithm based on pairs of coplanar points is proposed as well as its error model. This algorithm is proved to be a solution of the "epipole dead zone" problem theoretically. Finally, numerical simulations show that the proposed distance estimation algorithm can effectively improve the accuracy of distance estimation in the "epipole dead zone". © 2019 IEEE.

关键词： Vision

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A study on the modified proportional guidance of LOS angle acceleration

A study on the modified proportional guidance of LOS angle a...

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2019 IEEE International Conference on Unmanned systems and Artificial Intelligence, ICUSAI 2019

作者： Li, Xingan Xu, Cheng Zhang, Di Fu, Wenxing Zheng, Meiyun Chang, Xiaofei School of Astronautics Northwestern Polytechnical University Xi'an China Science and Technology on Complex System Control and Intelligent Agent Cooperation Laboratory Beijing China Shanghai Academy of Spaceflight Technology Shanghai China Unmanned System Research Institute Northwestern Polytechnical University Xi'an China School of Marine Science and Technology Northwestern Polytechnical University Xi'an China

ISBN: (纸本)9781728158594

Because of the increasing mobility of air targets and the trend of heavy using of UAV in the future, the paper analyzes the parameters and ballistic characteristics of the proportional guidance method based on the revised idea of proportional guidance. The method has certain defects in the face of high maneuvering targets, so we have derived a kind of modified proportional guidance law, and designed a new modified proportional guidance law which can effectively overcome the target maneuvering interference. The digital simulation results show that the modified guidance law can effectively overcome the interference factors such as target maneuvering, and it is easy to implement in engineering. © 2019 IEEE.

关键词： Air navigation

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