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Improving preparation and luminescence properties of Eu and dy doped Sr₂MgSi₂O₇ phosphors by adding excess silica

Scientific Reports 2025年第1期15卷 1-14页

作者： Zhang, Chi Wei, Liuming Liu, Qin Cui, Ruirui Deng, Chaoyong Li, Jingyu College of Electrical Engineering Henan University of Technology Zhengzhou 450001 China Department of Network Security Henan Police College Zhengzhou 450046 China Spallation Neutron Source Science Center Dongguan 523803 China Key Laboratory of Functional Composite Materials of Guizhou Province College of Big Data and Information Engineering Guizhou University Guiyang 550025 China Anqiu Qingyun Bilingual School Weifang China

Solid state reaction method is most commonly used to synthesize Sr2MgSi2O7: Eu2+, Dy3+ phosphors. In order to avoid the energy waste caused by high sintering temperature, we systematically studied and optimized the pr... 详细信息

Solid state reaction method is most commonly used to synthesize Sr₂MgSi₂O₇: Eu²⁺, Dy³⁺ phosphors. In order to avoid the energy waste caused by high sintering temperature, we systematically studied and optimized the preparation process of Sr₂MgSi₂O₇: Eu²⁺, Dy³⁺ long afterglow phosphors by increasing the Si/Sr ratio in the raw materials. The appropriate addition of silica not only facilitates the preparation of single phase Sr₂MgSi₂O₇: Eu²⁺, Dy³⁺ phosphor but also enhances the rate of solid state reaction, so as to achieve the purpose of reducing the sintering temperature. The photoluminescence performance of the sample with a Si/Sr ratio of 1.1 sintered at 1350 °C is the highest, followed by that of the sample sintered at 1400 °C with a Si/Sr ratio of 1.0. Notably, the photoluminescence properties of the Si/Sr ratio of 1.3 sample sintered at 1300 °C are comparable to those of the Si/Sr ratio of 1.0 sample sintered at 1400 °C. However, in terms of afterglow properties, the former exhibits an enhancement by a factor of 3.5 compared to the latter. This finding suggests that strategically increasing the Si/Sr ratio can reduce the sintering temperature by 100 °C while maintaining or even enhancing the luminescence and afterglow properties of the samples. Additionally, the electronic structures of the Sr₂MgSi₂O₇ host, the doped luminescence center Eu, the oxygen vacancies and the co-doped activator Dy have been methodically investigated through first-principles calculations. By integrating the findings on the distribution of the dopants and defects levels, we predict and propose the photoluminescence and afterglow mechanisms of Sr₂MgSi₂O₇: Eu²⁺, Dy³⁺. These studies suggest an efficient, cheap and energy-saving strategy for t

关键词： Electron traps First-principles calculation Optimizing synthesis Persistent luminescence Sr2MgSi2O7

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Spin-induced orbital frustration in a hexagonal optical lattice

arXiv

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arXiv 2021年

作者： Li, Yongqiang Yuan, Jianmin Zhou, Xiaoji Li, Xiaopeng Department of Physics National University of Defense Technology Changsha410073 China Department of Physics Graduate School of China Academy of Engineering Physics Beijing100193 China State Key Laboratory of Advanced Optical Communication System and Network Department of Electronics Peking University Beijing100871 China State Key Laboratory of Surface Physics Institute of Nanoelectronics and Quantum Computing Department of Physics Fudan University Shanghai200438 China Shanghai Qi Zhi Institute AI Tower Xuhui District Shanghai200232 China

Complex lattices provide a versatile ground for fascinating quantum many-body physics. Here, we propose an exotic mechanics for generating orbital frustration in hexagonal lattices. We study two-component (pseudospin-1/2) Bose gases in p-orbital bands of two-dimensional hexagonal lattices, and find that the system exhibits previously untouched orbital frustration as a result of the interplay of spin and orbital degrees of freedom, in contrast to normal Ising-type orbital ordering of spinless porbital band bosons in two-dimensional hexagonal lattices. Based on the classification by symmetry analysis, we find the interplay of orbital frustration and strong interaction leads to exotic Mott and superfluid phases with spin-orbital intertwined orders, in spite of the complete absence of spin-orbital interaction in the Hamiltonian. Our study implies many-body correlations in a multi-orbital setting could induce rich spin-orbital intertwined physics in complex lattice structures. Copyright © 2021, The Authors. All rights reserved.

关键词： Bosons

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Global context aware RCNN for object detection

arXiv

引用

arXiv 2020年

作者： Zhang, Wenchao Fu, Chong Xie, Haoyu Zhu, Mai Tie, Ming Chen, Junxin School of Computer Science and Engineering Northeastern University Shenyang110819 China Engineering Research Center of Security Technology of Complex Network System Ministry of Education China Key Laboratory of Intelligent Computing in Medical Image Ministry of Education Northeastern University Shenyang110819 China Science and Technology on Space Physics Laboratory Beijing100076 China College of Medicine and Biological Information Engineering Northeastern University Shenyang110819 China

RoIPool/RoIAlign is an indispensable process for the typical two-stage object detection algorithm, it is used to rescale the object proposal cropped from the feature pyramid to generate a fixed size feature map. However, these cropped feature maps of local receptive fields will heavily lose global context information. To tackle this problem, we propose a novel end-to-end trainable framework, called Global Context Aware (GCA) RCNN, aiming at assisting the neural network in strengthening the spatial correlation between the background and the foreground by fusing global context information. The core component of our GCA framework is a context aware mechanism, in which both global feature pyramid and attention strategies are used for feature extraction and feature refinement, respectively. Specifically, we leverage the dense connection to improve the information flow of the global context at different stages in the top-down process of FPN, and further use the attention mechanism to refine the global context at each level in the feature pyramid. In the end, we also present a lightweight version of our method, which only slightly increases model complexity and computational burden. Experimental results on COCO benchmark dataset demonstrate the significant advantages of our approach. Copyright © 2020, The Authors. All rights reserved.

关键词： Object recognition

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An improved RL-based framework for multiple biomedical event extraction via self-supervised learning

An improved RL-based framework for multiple biomedical event...

引用

IEEE International Conference on Bioinformatics and Biomedicine (BIBM)

作者： Yao Zhao Weizhong Zhao Xingpeng Jiang Tingting He Bianping Su Hubei Provincial Key Laboratory of Artificial Intelligence and Smart Learning Central China Normal University Wuhan Hubei PR China School of Computer Central China Normal University Wuhan Hubei PR China National Language Resources Monitoring & Research Center for Network Media Central China Normal University Wuhan Hubei PR China Guangxi Key Laboratory of Trusted Software Guilin University of Electronic Technology Guilin PR China Guangxi Key Lab of Multi-source Information Mining & Security Guangxi Normal University Guilin PR China Xi’an University of Architecture and Technology Xi’an Shanxi PR China

ISBN: (纸本)9781665429825

The main goal of biomedical event extraction is to structurally extract biomedical events from texts, however, the specificity of the domain makes both text modeling and data annotation very difficult. We propose a self-supervised learning-based data augmentation method in this paper and design specific augmentation strategies for biomedical entities and event triggers in biomedical texts, which solves the problem of sparse annotation data to some extent. In addition we improve the reinforcement learning-based event extraction method to improve the training efficiency of the model. The experiments on two datasets demonstrate the effectiveness of our method.

关键词： Training Annotations Conferences Biological system modeling Data models Data mining Bioinformatics

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DQ-RM: Deep Reinforcement Learning-based Route Mutation Scheme for Multimedia Services

DQ-RM: Deep Reinforcement Learning-based Route Mutation Sche...

引用

International Wireless Communications and Mobile computing Conference, IWCMC

作者： Tao Zhang Changqiao Xu Bingchi Zhang Xiaohui Kuang Yue Wang Shujie Yang Gabriel-Miro Muntean State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing China School of International Beijing University of Posts and Telecommunications Beijing China State key Laboratory of Science and Technology on Information System Security Beijing China Beijing Key Laboratory of Network System Architecture and Convergence Beijing China Performance Engineering Lab. School of Electronic Engineering Dublin City University Dublin Ireland

ISBN: (数字)9781728131290

ISBN: (纸本)9781728131306

Increasingly growing various multimedia services (e.g., interactive live video and so on) have brought tremendous pressure on existing static defense techniques. To cope with inherent drawback of static defense techniques, network Moving Target Defense (NMTD) such as route mutation (RM) was proposed. What's more, applying reinforcement learning (RL) into RM has been proved feasible in our previous work. But two main problems still need to be considered in this combination of RL with RM: 1) It lacks the consideration of multiple flows situation. 2) With the state-action space grow larger, current solution can't handle efficiently. In this paper, we propose a deep Q-learning method for RM (DQ-RM) to solve above two problems. Firstly, benefited from the satisfiability module theory, we formalize RM space considering single flow and multiple flows concurrently. Then we further propose a deep reinforcement learning-based RM scheme based on our previous work, which is suitable for large-scale state-action space. Finally, extensive experimental results highlight the improvement of DQ-RM in defense performance and convergence speed compared to the representative solution.

关键词： Routing Streaming media Machine learning Frequency modulation Computer crime Convergence Quality of service

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A novel Image security Protection Method Based on DCT Compression Theory and Hyper-chaotic Mapping

引用

Journal of Physics: Conference Series 2021年第1期2066卷

作者： Xianglian Xue Haiyan Jin School of Computer Science and Engineering Xi'an University of Technology Xi'an 710077Shaanxi China Shaanxi University of Chinese Medicine Xianyang712046Shaanxi China Shaanxi Key Laboratory for Network Computing and Security Technology Xi'an University of Technology Xi'an710077Shaanxi China

This paper studies the current situation of image compression encryption and analyzes the influence of low frequency (DC coefficient) and high frequency (AC coefficient) on image structure in DCT transformation. Based on this, a novel image security protection method based on DCT compression theory and hyper-chaotic mapping is proposed. First, the position of the pixel of the original image is disturbed, and converts the image from spatial domain into frequency domain by the two-dimensional DCT transformation and quantization. Second, change the pixel values by modifying the values of the sign bit of AC coefficient and DC coefficient. At last, the encrypted image is obtained by carrying out inverse quantization, inverse transformation and reverse operation by bit.

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Average Channel Capacity Analysis for Visible Light Communications with Random Receivers

Average Channel Capacity Analysis for Visible Light Communic...

引用

International Conference on Wireless Communications and Signal Processing (WCSP)

作者： Xian-Tao Fu Rong-Rong Lu Sheng-Hong Lin Jin-Yuan Wang Key Lab of Broadband Wireless Communication and Sensor Network Technology Ministry of Education Nanjing University of Posts and Telecommunications Nanjing China Shanghai Key Laboratory of Trustworthy Computing East China Normal University Shanghai China Key Laboratory of Opto-technology and Intelligent Control Ministry of Education Lanzhou Jiaotong University Lanzhou China National Local Joint Engineering Research Center for Communication and Network Technologies Nanjing University of Posts and Telecommunications Nanjing China

ISBN: (数字)9781728172361

ISBN: (纸本)9781728172378

For indoor visible light communications (VLC), the receivers are usually set to be fixed ones in previous studies. However, the locations and orientations of receivers are affected by random factors in practical VLC systems. In this paper, the performance of VLC with random receivers is investigated. We consider an VLC system, which consists of a transmitter and a receiver. The main noise is additive white Gaussian noise. Two random factors (i.e., random location and random orientation) of the receiver are considered. Based on the established system model, closed-form expressions of the average channel capacity for systems with random location and random orientation are derived, respectively. Numerical results verify the accuracy of the derived theoretical expressions. Moreover, the impacts of the nominal optical intensity, the dimming target, the transmitter height and the Lambertian emission order on system performance are also discussed.

关键词： Visible light communication Optical transmitters Optical receivers Light emitting diodes Channel capacity High-speed optical techniques Wireless communication

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Predicting Internet of Things Data Traffic Through LSTM and Autoregressive Spectrum Analysis

Predicting Internet of Things Data Traffic Through LSTM and ...

引用

IEEE Symposium on network Operations and Management

作者： Yuhong Li Di Jin Bailin Wang Xiang Su Jukka Riekki Chao Sun Hanyu Wei Hao Wang Lei Han State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing China Department of Computer Science University of Helsinki Helsinki Finland Center for Ubiquitous Computing University of Oulu Oulu Finland Network Technology Laboratory Huawei Technologies Co. Ltd Nanjing China

ISBN: (数字)9781728149738

ISBN: (纸本)9781728149745

The rapid increase of Internet of Things (IoT) applications and services has led to massive amounts of heterogeneous data. Hence, we need to re-think how IoT data influences the network. In this paper, we study the characteristics of IoT data traffic in the context of smart cities. Aiming at analyzing the influence of IoT data traffic on the access and core network, we generate various IoT data traffic according to the characteristics of different IoT applications. Based on the analysis of the inherent features of the aggregated IoT data traffic, we propose a Long Short-Term Memory (LSTM) model combined with autoregressive spectrum analysis to predict the IoT data traffic. In this model, the autoregressive spectrum analysis is used to estimate the minimum length of the historical data needed for predicting the traffic in the future, which alleviates LSTM's performance deterioration with the increase of sequence length. A sliding window enables predicting the long¬term tendency of IoT data traffic while keeping the inherent features of the data traffic. The evaluation results show that the proposed model converges quickly and can predict the variations of IoT traffic more accurately than other methods and the general LSTM model.

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Modulation Recognition based on Incremental Deep Learning

Modulation Recognition based on Incremental Deep Learning

引用

International Conference on Mechanical, Control and Computer Engineering (ICMCCE)

作者： Yong Yang Menghan Chen XiaoYa Wang Piming Ma The 54th Research Institute of CETC Shijiazhuang China School of Information Science and Engineering Shandong University Qingdao China School of Information and Communication Engineering National Engineering Laboratory for Mobile Network Security Key Laboratory of Trustworthy Distributed Computing and Service Beijing University of Posts and Telecommunications line Beijing China

Incremental learning has emerged to solve the problem of incrementally updating the classification model as the number of data classes grows. There are many challenges in incremental learning such as catastrophic forgetting and learning efficiency. In this paper, we present a method of the modulation recognition based on incremental learning, that allows learning continuously with a class-incremental way. The new classes can be added into the existing model progressively from a sequential data stream. We conduct experiments on the modulation signal dataset characterized by the constellation diagram, the experimental results prove the feasibility of our incremental learning system. Our method performs similarly in classification accuracy compared to common multi-task joint training, but performs better in training efficiency.

关键词： Training Learning systems Deep learning Constellation diagram Memory management Modulation Aerospace electronics

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A Joint Operation Method of Fuzzy Test and Dynamic Symbol Execution

A Joint Operation Method of Fuzzy Test and Dynamic Symbol Ex...

引用

International Conference on Intelligent Computation technology and Automation, ICICTA

作者： Zesheng Xi Gongxuan Zhang Bo Zhang School of Computer Science and Engineering Nanjing University of Science and Technology Nanjing China Institute of Information and Communication Global Energy Interconnection Research Institute Nanjing China State Grid Key Laboratory of Information & Network Security Nanjing China

Fuzzy testing and symbol execution are the main methods of vulnerability mining for binary programs. Among them, fuzzy testing is time-consuming due to randomness, while symbol execution is limited by path explosion due to traversal. At present, there is a certain research foundation about the mixed test of fuzzy test and symbol execution, but most of them focus on improving the code coverage and other indicators. There is no clear method for how to call each other in the hybrid test process of fuzzy test and symbol execution. In this paper, combined with the strong interpretability of decision tree algorithm, a hybrid test call strategy based on decision tree is proposed, which quantifies the factors that affect the efficiency of hybrid test, and clarifies the reasons for triggering call between fuzzy test and symbol execution, which is helpful to improve the efficiency of hybrid test.

关键词： Codes Automation Explosions Decision trees Testing

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