检索结果-内蒙古大学图书馆

SSRN 2023年

作者： Zhao, Honggang Deng, Bozhi Liu, Yuanxue Huang, Gun Song, Zhenlong Chongqing Key Laboratory of Geomechanics & Geoenvironmental Protection Department of Military Installations Army Logistics Academy of PLA Chongqing401311 China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing University Chongqing400030 China School of Resources and Safety Engineering Chongqing University Chongqing400030 China School of Civil and Environmental Engineering Georgia Institute of Technology AtlantaGA United States Department of Earth and Space Sciences Southern University of Science and Technology Shenzhen518055 China

In this study, we meticulously scrutinize the correlation between the thickness of the weak interlayer and its effect on mechanical behavior and fracture characteristics, with the aid of a true triaxial test system. We rendered a simulation that mimics the stress state and boundary conditions of surrounding rocks containing weak interlayers proximate to the excavation boundary, where one face remains free, while others are subjected to loading stress and increasing tangential stress. The experimental results reveal a distinct change in the fracture morphology near the free surface as the weak interlayer thickness augments, concomitant with a gradual decrement in the fractal dimension. With the increase of the weak interlayer thickness, the failure characteristics of composite rock changes from "binary" feature to "unitary" feature, i.e. mixed tension-shear failure near the free surface and shear failure far away from the free surface changes to mixed tension-shear failure that only occurs near the free surface. Moreover, an inverse relationship is observed between the bearing capacity of the composite rock mass and the thickness of the weak interlayer. In opposition, there's an incremental trend in peak strain in the tangential stress direction, illustrating that the slip shear strain of the rock positioned above the weak interlayer chiefly governs the strain behavior of the composite rock mass in the tangential stress direction, and such strain intensifies with the enlargement of the weak interlayer. By employing the combined finite-discrete element method (FDEM), we've replicated the failure process of the surrounding rock with a weak interlayer near the free surface of the tunnel, demonstrating considerable congruity with our physical test results. In light of the failure characteristics of the surrounding rock with the weak interlayer, we advocate for a localized area priority reinforcement support strategy, prioritizing regions with weak interlayers. Numerical

关键词： Shear strain

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The strength of nesterov’s extrapolation in the individual convergence of nonsmooth optimization

TechRxiv

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TechRxiv 2020年

作者： Tao, Qing Tao, Wei Pan, Zhisong Wu, Gaowei Command and Control Engineering College Army Engineering University of PLA Nanjing210007 China Institute of Automation Chinese Academy of Sciences China Army Academy Of Artillery and Air Defense Hefei230031 China

The extrapolation strategy raised by Nesterov, which can accelerate the convergence rate of gradient descent methods by orders of magnitude when dealing with smooth convex objective, has led to tremendous success in training machine learning tasks. In this article, the convergence of individual iterates of projected subgradient (PSG) methods for nonsmooth convex optimization problems is theoretically studied based on Nesterov’s extrapolation, which we name individual convergence. We prove that Nesterov’s extrapolation has the strength to make the individual convergence of PSG optimal for nonsmooth problems. In light of this consideration, a direct modification of the subgradient evaluation suffices to achieve optimal individual convergence for strongly convex problems, which can be regarded as making an interesting step toward the open question about stochastic gradient descent (SGD) posed by Shamir. Furthermore, we give an extension of the derived algorithms to solve regularized learning tasks with nonsmooth losses in stochastic settings. Compared with other state-of-the-art nonsmooth methods, the derived algorithms can serve as an alternative to the basic SGD especially in coping with machine learning problems, where an individual output is needed to guarantee the regularization structure while keeping an optimal rate of convergence. Typically, our method is applicable as an efficient tool for solving large-scale l1-regularized hinge-loss learning problems. Several comparison experiments demonstrate that our individual output not only achieves an optimal convergence rate but also guarantees better sparsity than the averaged solution. © 2020, CC BY.

关键词： Extrapolation

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Toward a direct measurement of the cosmic acceleration: the first preparation with FAST

arXiv

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arXiv 2021年

作者： Lu, Chang-Zhi Jiao, Kang Zhang, Tingting Zhang, Tong-Jie Zhu, Ming Institute for Frontiers in Astronomy and Astrophysics Beijing Normal University Beijing102206 China Department of Astronomy Beijing Normal University Beijing100875 China College of Command and Control Engineering PLA Army Engineering University Nanjing210000 China Institute for Astronomical Science Dezhou University Dezhou253023 China National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China

Damped Lyman-α Absorber(DLA) of HI 21cm system is an ideal probe to directly measure cosmic acceleration in real-time cosmology via Sandage-Loeb(SL) test. During short observations toward two DLAs in the commissioning progress of FAST, we manage to exhibit an HI 21cm absorption feature from PKS1413+135 spectrum in one epoch with our highest resolution up to 100 Hz, preliminarily validating the frequency consistency under different resolutions and bandwidths. We make a Gaussian fitting to extract the spectral features, introduce two theoretical indicators to describe the fitted velocity uncertainty, and ultimately give a mean redshift and its constraint of zM = 0.24670045 ± 0.00000036 in accord with most literature. But our redshift error of the target is still three magnitudes higher than the level we can reach the drift signal. Though our first preparation has some flaws in time recording and diode settings, it still proves the correctness of our data process. Confined by limited observing time, we do not strech FAST’s ability to obtain a better velocity constraint, so further researchs are needed and in schedule. With fine sensitivity and improving spectral resolution, such observations in FAST could have reasonable possibility to explore cosmic acceleration in late time universe practically. Copyright © 2021, The Authors. All rights reserved.

关键词： Cosmology

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DNS based measurement and analysis of IPv6 domain name support 3

DNS based measurement and analysis of IPv6 domain name suppo...

引用

2020 3rd International Symposium on Big Data and Applied Statistics, ISBDAS 2020

作者： Li, Feng Cao, Huaping Ma, Weijun Hu, Chao Wang, Zhanfeng Lu, Xiyu Nanjing NO.1 Military Representative Department of Equipment Development Ministry Nanjing210007 China Beijing100029 China Nanjing Goldenwater Shangyang Information Technology Co. Ltd Nanjing city210014 China College of Command and Control Engineering Army Engineering University of Pla Nanjing210007 China School of Computer Science and Engineering Southeast University Nanjing211189 China

At present, the IPv4 addresses has been fully allocated, and the worldwide deployment of IPv6 addresses is accelerating due to its advantages. In order to investigate current development of IPv6, the IPv6 addresses of domain names are firstly resolved by DNS servers, and the obtained IPv6 addresses data, mainly including the geographic location statistics of IPv6, the proportion of southeast coastal cities, the comprehensive statistics of top-level domain names, etc., can be used to analyze the domain name supported by IPv6. The analysis of the measurement results has great guiding significance for further understanding the future development and application of IPv6. © Published under licence by IOP Publishing Ltd.

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Container Networking Performance Analysis for Large-Scale User Behavior Simulation

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Journal of Computer and Communications 2019年第10期7卷 136-146页

作者： Yifang Ji Guomin Zhang Shengxu Xie Xiulei Wang Command & Control Engineering College Army Engineering University of PLA Nanjing China

Accurately simulating large-scale user behavior is important to improve the similarity between the cyber range and the real network environment. The Linux Container provides a method to simulate the behavior of large-scale users under the constraints of limited physical resources. In a container-based virtualization environment, container networking is an important component. To evaluate the impact of different networking methods between the containers on the simulation performance, the typical container networking methods such as none, bridge, macvlan were analyzed, and the performance of different networking methods was evaluated according to the throughput and latency metrics. The experiments show that under the same physical resource constraints, the macvlan networking method has the best network performance, while the bridge method has the worst performance. This result provides a reference for selecting the appropriate networking method in the user behavior simulation process.

关键词： Linux Container Networking Mode Network Performance User Behavior Simulation

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Multi-type ant system algorithm for the time dependent vehicle routing problem with time windows

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Journal of Systems engineering and Electronics 2018年第3期29卷 625-638页

作者： DENG Ye ZHU Wanhong LI Hongwei ZHENG Yonghui College of Field Engineering Army Engineering University of PLA Department of Fire Control Armored Force Institute of PLA

The time dependent vehicle routing problem with time windows（TDVRPTW） is considered. A multi-type ant system（MTAS） algorithm hybridized with the ant colony system（ACS）and the max-min ant system（MMAS） algorithms is proposed. This combination absorbs the merits of the two algorithms in solutions construction and optimization separately. In order to improve the efficiency of the insertion procedure, a nearest neighbor selection（NNS） mechanism, an insertion local search procedure and a local optimization procedure are specified in detail. And in order to find a balance between good scouting performance and fast convergence rate, an adaptive pheromone updating strategy is proposed in the MTAS. Computational results confirm the MTAS algorithm＇s good performance with all these strategies on classic vehicle routing problem with time windows（VRPTW） benchmark instances and the TDVRPTW instances, and some better results especially for the number of vehicles and travel times of the best solutions are obtained in comparison with the previous research.

关键词： multi-type ant system（MTAS） time dependent vehicle routing problem with time windows（VRPTW） nearest neighbor selection（NNS）

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A Search for Extraterrestrial Technosignatures in Archival FAST Survey Data Using a New Procedure

arXiv

引用

arXiv 2023年

作者： Wang, Yu-Chen Tao, Zhen-Zhao Zhang, Zhi-Song Lyu, Cheqiu Zhang, Tingting Zhang, Tong-Jie Werthimer, Dan Institute for Frontiers in Astronomy and Astrophysics Beijing Normal University Beijing102206 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China Department of Astronomy School of Physics Peking University Beijing100871 China Department of Astronomy Beijing Normal University Beijing100875 China Institute for Astronomical Science Dezhou University Dezhou253023 China National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China College of Command and Control Engineering Army Engineering University Nanjing210017 China Breakthrough Listen University of California Berkeley BerkeleyCA94720 United States Space Sciences Laboratory University of California Berkeley BerkeleyCA94720 United States

The "search for extraterrestrial intelligence" (SETI) commensal surveys aim to scan the sky to find possible technosignatures from the extraterrestrial intelligence (ETI). The mitigation of radio frequency interference (RFI) is an important step, especially for the most sensitive Five-hundred-meter Aperture Spherical radio Telescope (FAST), which can detect more weak RFI. In this paper, we propose several new techniques for RFI mitigation, and use our procedure to search for ETI signals from the archival data of FAST’s first SETI commensal survey. We detect the persistent narrowband RFI by setting a threshold of the signals’ sky separation, and detect the drifting RFI (and potentially other types of RFI) using the Hough transform. We also use the clustering algorithms to remove more RFI and select candidates. The results of our procedure are compared to the earlier work on the same FAST data. We find that our methods, though relatively simpler in computation, remove more RFI (99.9912% compared to 99.9063% in the earlier work), but preserve the simulated ETI signals except those (5.1%) severely affected by the RFI. We also report more interesting candidate signals, about a dozen of which are new candidates that are not previously reported. In addition, we find that the proposed Hough transform method, with suitable parameters, also has the potential to remove the broadband RFI. We conclude that our methods can effectively remove the vast majority of the RFI while preserving and finding the candidate signals that we are interested in. Copyright © 2023, The Authors. All rights reserved.

关键词： Radio astronomy

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A Reliable Calibration of HII Galaxies Hubble Diagram with Cosmic Chronometers and Artificial Neural Network

arXiv

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arXiv 2022年

作者： Zhang, Jian-Chen Jiao, Kang Zhang, Tingting Zhang, Tong-Jie Yu, Bo Institute for Frontiers in Astronomy Astrophysics of Beijing Normal University Beijing100875 China Department of Astronomy Beijing Normal University Beijing100875 China College of Computer and Information Engineering Dezhou University Dezhou253023 China Institute for Astronomical Science Dezhou University Dezhou253023 China Dipartimento di Fisica e Astronomia "Augusto Righi" Alma Mater Studiorum Università di Bologna via Piero Gobetti 93/2 BolognaI-40129 Italy College of Command and Control Engineering PLA Army Engineering University Nanjing210000 China School of Mathematics and Big Data Dezhou University Dezhou253023 China Shandong Provincial Key Laboratory of Biophysics Institute of Biophysics Dezhou University Dezhou253023 China

The L − σ relation of HII galaxies (HIIGx) calibrated by a distance indicator is a reliable standard candle for measuring the Hubble constant H0. The most straightforward calibration technique anchors them with the first tier of distance ladders from the same galaxies. Recently another promising method that uses the cosmological model-independent Cosmic Chronometers (CC) as a calibrator has been proposed. We promote this technique by removing the assumptions about the cosmic flatness and using a non-parametric Artificial Neural Network for the data reconstruction process. We observe a correlation between the cosmic curvature density parameter and the slope of the L−σ relation, thereby improving the reliability of the calibration. Using the calibrated HIIGx Hubble diagram, we obtain a Type Ia Supernovae Hubble diagram free of the conventional assumption about H0. Finally we get a value of H0 = 65.9+3.0−2.9 km s−1 Mpc−1, which is compatible with latest planck18 measurement. © 2022, CC BY.

关键词： Supernovae

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Test of Artificial Neural Networks in Likelihood-free Cosmological Constraints: A Comparison of IMNN and DAE

arXiv

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arXiv 2022年

作者： Chen, Jie-Feng Wang, Yu-Chen Zhang, Tingting Zhang, Tong-Jie Institute for Frontiers in Astronomy and Astrophysics Department of Astronomy Beijing Normal University Beijing102206 China Department of Astronomy Beijing Normal University Beijing100875 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China Department of Astronomy School of Physics Peking University Beijing100871 China Department of Physics Beijing Normal University Beijing100875 China College of Command and Control Engineering Army Engineering University Nanjing210017 China Institute for Astronomical Science Dezhou University Dezhou253023 China

In the procedure of constraining the cosmological parameters with the observational Hubble data, the combination of Masked Autoregressive Flow and Denoising Autoencoder can perform a good result. The above combination extracts the features from OHD with DAE, and estimates the posterior distribution of H0, Ωm, ΩΛ with MAF. We ask whether we can find a better tool to compress large data in order to gain better results while constraining the cosmological parameters. Information maximising neural networks, a kind of simulation-based machine learning technique, was proposed at an earlier time. In a series of numerical examples, the results show that IMNN can find optimal, non-linear summaries robustly. In this work, we mainly compare the dimensionality reduction capabilities of IMNN and DAE. We use IMNN and DAE to compress the data into different dimensions and set different learning rates for MAF to calculate the posterior. Meanwhile, the training data and mock OHD are generated with a simple Gaussian likelihood, the spatially flat ΛCDM model and the real OHD data. To avoid the complex calculation in comparing the posterior directly, we set different criteria to compare IMNN and DAE. Copyright © 2022, The Authors. All rights reserved.

关键词： Neural networks

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Structural combinatorial of network information system of systems based on evolutionary optimization method

arXiv

引用

arXiv 2020年

作者： Zhang, Tingting Lan, Yushi Song, Aiguo Liu, Kun Wang, Nan Computer and military software engineering PLA Army Engineering University Nanjing China National defense key laboratory China Electronics Technology Group Corporation Nanjing China College of Instrument Science and Engineering Southeast University Nanjing China College of Command and Control Engineering PLA Army Engineering University Nanjing China

The network information system is a military information network system with evolution characteristics. Evolution is a process of replacement between disorder and order, chaos and equilibrium. Given that the concept of evolution originates from biological systems, in this article, the evolution of network information architecture is analyzed by genetic algorithms, and the network information architecture is represented by chromosomes. Besides, the genetic algorithm is also applied to find the optimal chromosome in the architecture space. The evolutionary simulation is used to predict the optimal scheme of the network information architecture and provide a reference for system construction. Copyright © 2020, The Authors. All rights reserved.

关键词： Genetic algorithms

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