检索结果-内蒙古大学图书馆

SSRN 2023年

作者： Hu, Qiongyu Yang, Kejian Li, Ming Li, Ping Zhao, Haoxu Zhang, Bin Liu, Jing Yang, Yongming Chen, Xiaohan Center for Optics Research and Engineering Key Laboratory of Laser & Infrared System Ministry of Education Shandong University Shandong Qingdao266237 China Institute of Novel Semiconductors State Key Laboratory of Crystal Materials Shandong University Jinan250100 China School of Information Science and Engineering Shandong Provincial Key Laboratory of Laser Technology and Application Shandong University Shandong Qingdao266237 China

The evolution of multiple pulses and the pump hysteresis phenomenon were observed in a passively mode-locked Er-doped fiber laser using an Sb2S3-PVA saturable absorber. As the pump power was increased, the generations of onefold, twofold, and threefold pulses were meticulously documented. When the pump power was decreased, the evolution of fivefold and sixfold pulses was carefully recorded, accompanied by a clear pump hysteresis phenomenon. A thorough analysis was conducted to examine and reveal the inversely proportional relationship between the RF spectrum modulation periods and the total pulse intervals of the multi-pulse bunches including from onefold to sixfold pulses. © 2023, The Authors. All rights reserved.

关键词： Hysteresis

DNN Task Assignment in UAV Networks: A Generative AI Enhanced Multi-Agent Reinforcement Learning Approach

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arXiv

arXiv 2024年

作者： Tang, Xin Chen, Qian Weng, Wenjie Liao, Binhan Wang, Jiacheng Cao, Xianbin Li, Xiaohuan Guangxi University Key Laboratory of Intelligent Networking and Scenario System School of Information and Communication Guilin University of Electronic Technology Guilin541004 China The College of Computing and Data Science Nanyang Technological University 639798 Singapore School of Architecture and Transportation Engineering Guilin University of Electronic Technology Guilin541004 China National Engineering Laboratory for Comprehensive Transportation Big Data Application Technology Guangxi Nanning530001 China College of Computing and Data Science Nanyang Technological University 639798 Singapore School of Electronic and Information Engineering The Key Laboratory of Advanced Technology of Near Space Information System Ministry of Industry and Information Technology of China Beihang University Beijing100191 China

Unmanned Aerial Vehicles (UAVs) possess high mobility and flexible deployment capabilities, prompting the development of UAVs for various application scenarios within the Internet of Things (IoT). The unique capabilities of UAVs give rise to increasingly critical and complex tasks in uncertain and potentially harsh environments. The substantial amount of data generated from these applications necessitates processing and analysis through deep neural networks (DNNs). However, UAVs encounter challenges due to their limited computing resources when managing DNN models. This paper presents a joint approach that combines multiple-agent reinforcement learning (MARL) and generative diffusion models (GDM) for assigning DNN tasks to a UAV swarm, aimed at reducing latency from task capture to result output. To address these challenges, we first consider the task size of the target area to be inspected and the shortest flying path as optimization constraints, employing a greedy algorithm to resolve the subproblem with a focus on minimizing the UAV’s flying path and the overall system cost. In the second stage, we introduce a novel DNN task assignment algorithm, termed GDM-MADDPG, which utilizes the reverse denoising process of GDM to replace the actor network in multi-agent deep deterministic policy gradient (MADDPG). This approach generates specific DNN task assignment actions based on agents’ observations in a dynamic environment. Simulation results indicate that our algorithm performs favorably compared to benchmarks in terms of path planning, Age of information (AoI), energy consumption, and task load balancing. Copyright © 2024, The Authors. All rights reserved.

关键词： Motion planning

A nonlocal interferometric phase filtering strategy for practical InSAR system

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A nonlocal interferometric phase filtering strategy for prac...

IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： Xue Lin Dongsheng Fang Fangfang Li Ke Wang Shandong Provincial Key Laboratory of Network Based Intelligent Computing Jinan China School of Information Science and Engineering University of Jinan Jinan China Institute of Electronics Chinese Academy of Sciences Beijing China University of Chinese Academy of Sciences Beijing China Key Laboratory of Technology in Geo-spatial Information Processing and Application System Chinese Academy of Sciences Beijing China School of Information Science and Engineering Henan University of Technology Zhengzhou China

Nonlocal interferometric phase filtering methods achieve excellent performance in both noise reduction and texture preservation, even in the case of complicated topography and low coherence. The main limitation of the nonlocal methods is the computational burden. This paper proposed a nonlocal phase filtering strategy for the practical InSAR system, which combine the nonlocal algorithm with the traditional method to improve the efficiency.

关键词： Filtering Coherence Noise reduction Frequency estimation Estimation Algorithm design and analysis Surfaces

Efficient Sparse MIMO SAR Imaging with Fast Iterative Method Based on Back Projection and Approximated Observation

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Efficient Sparse MIMO SAR Imaging with Fast Iterative Method...

Electronics and Electrical Engineering technology (EEET), International Conference on

作者： Pengyu Jiang Zhe Zhang Bingchen Zhang Key Laboratory of Technology in Geo-Spatial Information Processing and Application System Chinese Academy of Sciences Beijing China Aerospace Information Research Institute Chinese Academy of Sciences Beijing China School of Electronic Electrical and Communication Engineering University of Chinese Academy of Sciences Beijing China Suzhou Aerospace Information Research Institute Suzhou China

Compressed sensing technique is widely used in the field of multiple input multiple output (MIMO) radar imaging to suppress sidelobes and noise, bringing better imaging performance. However, many constraints are introduced to the sparse reconstruction model, current sparse microwave imaging model is based on several assumptions, such as far field assumption, which might not hold in some circumstances. In this paper, a novel two-dimensional sparse reconstruction method based on approximated observation is proposed. First, we obtain the measurement matrix by the inverse back-projection operator, and construct a two-dimensional sparse reconstruction model. Then, we adopt the minimax concave constraint as the regularization term and use the iterative soft threshold algorithm (ISTA) for sparse reconstruction. The method retains the advantages of the BP algorithm and the sparse reconstruction algorithm at the same time, and the distance between the target and the antenna array is not constrained by image reconstruction performance of the sparse reconstruction algorithm. Simulations and experiments demonstrate the effectiveness of the proposed method.

关键词： MIMO radar Simulation Imaging Radar imaging Reconstruction algorithms Sparse matrices Velocity measurement

Peer is Your Pillar: A Data-unbalanced Conditional GANs for Few-shot Image Generation

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arXiv

arXiv 2023年

作者： Li, Ziqiang Wang, Chaoyue Rui, Xue Xue, Chao Leng, Jiaxu Li, Bin Big Data and Decision Lab University of Science and Technology of China China The University of Sydney Australia JD Explore Academic China School of computer science Chongqing University of Posts and Telecommunications China CAS Key Laboratory of Technology in Geo-spatial Information Processing and Application System China

Few-shot image generation aims to train generative models using a small number of training images. When there are few images available for training (e.g. 10 images), Learning From Scratch (LFS) methods often generate images that closely resemble the training data while Transfer Learning (TL) methods try to improve performance by leveraging prior knowledge from GANs pre-trained on large-scale datasets. However, current TL methods may not allow for sufficient control over the degree of knowledge preservation from the source model, making them unsuitable for setups where the source and target domains are not closely related. To address this, we propose a novel pipeline called Peer is your Pillar (PIP), which combines a target few-shot dataset with a peer dataset to create a data-unbalanced conditional generation. Our approach includes a class embedding method that separates the class space from the latent space, and we use a direction loss based on pre-trained CLIP to improve image diversity. Experiments on various few-shot datasets demonstrate the advancement of the proposed PIP, especially reduces the training requirements of few-shot image generation. © 2023, CC BY.

关键词： Large dataset

Compact Ld Side-Pumped Nd:Yag Oscillator at 100 Hz Without Water-Cooling

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SSRN 2023年

作者： Yang, Zeqi Cong, Zhenhua Meng, Jun Wang, Shang Zhao, Zhigang Liu, Gaoyou Liu, Zhaojun Key Laboratory of Laser and Infrared System Integration Technology Ministry of Education Shandong University Qingdao266237 China The School of Information Science and Engineering Shandong University Qingdao266237 China Shandong Provincial Key Laboratory of Laser Technology and Application Shandong University Qingdao266237 China Center for Optics Research and Engineering Shandong University Qingdao266237 China

A high-repetition-frequency side-pumped electro-optical (E-O) Q-switched Nd:YAG laser without water cooling is reported. A 100 Hz laser module without water-cooling was designed and the related parameters of crystal are simulated. The crystal is annularly pumped in both ends and is conductively cooled in the middle. The heat generated by crystal and laser diode is dissipated by thermoelectric cooler (TEC), fins and fan. The 1064 nm maximum output energy is 68 mJ with a pulse width of 31 ns and a repetition rate of 100 Hz. The optical-optical conversion efficiency is 10.6%. To the best of our knowledge, this is the first report of 100 Hz repetition rate operation for a E-O Q-switched Nd:YAG rod laser without water-cooling. © 2023, The Authors. All rights reserved.

关键词： Yttrium aluminum garnet

Satellite-observed changes in terrestrial vegetation growth trends across the Asia-Pacific region associated with land cover and climate from 1982 to 2011

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International Journal of Digital Earth 2016年第11期9卷 1055-1076页

作者： Baozhang Chen Guang Xu Nicholas C.Coops Philippe Ciais Ranga B.Myneni Key Laboratory of Soil and Water Conservation and Desertification Combating Ministry of EducationBeijing Forestry UniversityBeijingPeople’s Republic of China School of Environment Science and Spatial Informatics China University of Mining and TechnologyXuzhouPeople’s Republic of China Jiangsu Center for Collaborative Innovation in Geographic Information Resource Development and Application NanjingPeople’s Republic of China State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijingPeople’s Republic of China University of Chinese Academy of Sciences BeijingPeople’s Republic of China Department of Forest Resource Management University of British ColumbiaVancouverBCCanada Laboratoire des Sciences du Climat et de l’Environnement UnitéMixte de Recherche Commissariatàl’Energie AtomiqueCentre National de la Recherche ScientifiqueUniversitéde Versailles Saint-Quentin-en-YvelinesGif-sur-YvetteFrance Department of Earth and Environment Boston UniversityBostonMAUSA

The Asia-Pacific(AP)region has experienced faster warming than the global average in recent decades and has experienced more climate extremes,however little is known about the response of vegetation growth to these *** updated Global Inventory Modeling and Mapping Studies third-generation global satellite Advanced Very High Resolution Radiometer Normalized Difference Vegetation Index dataset and gridded reanalysis climate data were used to investigate the spatiotemporal changes in both trends of vegetation dynamic indicators and climatic *** then further analyzed their relations associated with land cover across the AP *** main findings are threefold:(1)at continental scales the AP region overall experienced a gradual and significant increasing trend in vegetation growth during the last three decades,and this NDVI trend corresponded with an insignificant increasing trend in temperature;(2)vegetation growth was negatively and significantly correlated with the Pacific Decadal Oscillation index and the El Niño/Southern Oscillation(ENSO)in AP;and(3)at pixel scales,except for Australia,both vegetation growth and air temperature significantly increased in the majority of study regions and vegetation growth spatially correlated with temperature;In Australia and other water-limited regions vegetation growth positively correlated with precipitation.

关键词： Vegetation dynamics NDVI climate change land cover Asia-Pacific region

K-Wise Multi-Graph Matching

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SSRN 2023年

作者： Zhu, Xinwen Zhu, Liangliang Geng, Xiurui Aerospace Information Research Institute Chinese Academy of Sciences Beijing100864 China School of Electronic Electrical and Communication Engineering University of Chinese Academy of Sciences Beijing100049 China Key Laboratory of Technology in Geo-Spatial Information Processing and Application System Chinese Academy of Sciences Beijing100864 China

Multi-graph matching, which aims to find the correspondences of multiple graphs, is an extension of conventional two-graph matching. There are mainly two categories of multi-graph matching methods, i.e., the pairwise-based methods and the tensor-based methods. Both of them try to find the correspondences between graphs by maximizing the values of the similarities between the corresponding features, e.g., nodes, edges, and so on. The difference is that for a set of features from different graphs to be matched, the pairwise-based methods consider the similarities of every two features, while the tensor-based methods directly consider the whole similarity among them. Therefore, the measurement of similarities in the tensor-based methods is usually much more flexible than that in the pairwise-based methods. However, the time and space complexities of the tensor-based methods grow geometrically as the number of graphs to be matched increases. In this paper, through a comprehensive investigation, we propose a k-wise multi-graph matching method which includes the aforementioned two kinds of methods as special cases. Generally, by choosing different value of k, it could be found that the proposed algorithm can strike a balance between flexible similarity measurement and low computational complexity. In addition, a factorization of k-wise global affinity matrix is proposed to save the computational cost of our method. Experiments with synthetic and real data demonstrate the superiority of our method. © 2023, The Authors. All rights reserved.

关键词： Tensors

Understanding the Long-Distance Travel Mobility of Passengers Based on Big Railway Data: Travel Network and Motif Perspectives

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SSRN 2022年

作者： Xu, Jin Song, Haonan Lu, Zhaoyang Department of Information System & Operation Management School of Economics and Management Southwest Jiaotong University Sichuan Chengdu China National Engineering Laboratory of Integrated Transportation Big Data Application Technology Sichuan Chengdu China Service Science and Innovation Key Laboratory of Sichuan Province Sichuan Chengdu China

With the booming construction of new railway lines and stations in China, the number of railway passengers is increasing. The large railway population shows certain mobility characteristics that we are interested in clarifying. Based on the theory of complex networks, this paper proposes a novel method to identify travel patterns from big railway data, which associates travel motifs with travel networks. This paper derives some meaningful results from the data analysis of more than three million railway travel records of a city in China. These results illustrate that higher motif complexity leads to a narrower travel radius for motif-based subnets. The higher the stability of the travel sequence is, the shorter the average length of the sequence. Four types of travel patterns are identified and classified by analyzing the motif of travel activities, i.e., labor, tourism, surrounding and commuting. The methodology and findings presented in this paper contribute to a better understanding of the long-distance travel mobility of railway passengers. The method designed in this paper can also be used to analyze traffic data from airlines, buses, subways, etc. © 2022, The Authors. All rights reserved.

关键词： Complex networks

Red edge characteristics and leaf area index estimation model using hyperspectral data for rape

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Rengong Jingti Xuebao/Journal of Synthetic Crystals 2006年第4期35卷 22-26页

作者： Huang, Jingfeng Wang, Yuan Wang, Fumin Liu, Zhanyu Institute of Agricultural Remote Sensing and Information Application Center of Agricultural Information Science and Technology Zhejiang University Key Laboratory of Agricultural Remote Sensing and Information System Application Hangzhou 310029 China

The hyperspectral reflectances for rape canopies consisting of five cultivars and three nitrogen levels were measured in 2003~2004 growth period by an ASD FieldSpec Pro FR [trademark] . The corresponding leaf area indices were observed. The red edge parameters were extracted using the spectral reflectances of the rape canopies. There exist 'two peak' phenomena for the red edge of rape canopy spectra. The position of red edge λred is located between 690 nm and 720 nm. There is a 'platform of red edge' at the bloom stage of rape. The red edge shift was detected before flowering stage and blue shift after flowering stage. The relationship between red edge parameters and the leaf area index (LAI) was investigated during 8 development periods. Results were not consistently significant at any wavelengths. The leaf area indices were significantly correlative to the red edge parameters λred, Dλred and Sred of the canopy spectra before flowering stage, whereas the correlation coefficient showed very low r values that were in significant after flowering stage. So the red edge parameters of rape canopies before the flowering stage can be used to estimate the leaf area indices. The results for different stages, linear and non-linear regression models were compared and the optimum model for LAI before flowering stage was recommended.

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