检索结果-内蒙古大学图书馆

numerical simulation based on two-directional freeze and thaw algorithm for thermal diffusion model

Applied mathematics and Mechanics(English Edition) 2016年第11期37卷 1467-1478页

作者： Junqiang GAO Zhenghui XIE Aiwen WANG Zhendong LUO State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences School of Mathematics and Physics North China Electric Power University School of Applied Science Beijing Information and Science Technology University

Freeze-thaw processes significantly modulate hydraulic and thermal char- acteristics of soil. The changes in the frost and thaw fronts （FTFs） affect the water and energy cycles between the land surface and the atmosphere. Thus, the frozen soil com- prising permafrost and seasonally frozen soil has important effects on the land surface hydrology in cold regions. In this study, a two-directional freeze and thaw algorithm is incorporated into a thermal diffusion equation for simulating FTFs. A local adaptive variable-grid method is used to discretize the model. Sensitivity tests demonstrate that the method is stable and FTFs can be tracked continuously. The FTFs and soil tempera- ture at the Qinghai-Tibet Plateau D66 site are simulated hourly from September 1, 1997 to September 22, 1998. The results show that the incorporated model performs much better in the soil temperature simulation than the original thermal diffusion equation, showing potential applications of the method in land-surface process modeling.

关键词： freeze and thaw algorithm frost and thaw front （FTF） sensitivity test,thermal diffusion equation

来源：评论

学校读者我要写书评

暂无评论

Anisotropic and mutable magnetization in Kondo lattice CeSb2

引用

Chinese physics B 2017年第6期26卷 319-323页

作者：张云朱燮刚胡丙锋谭世勇谢东华冯卫刘琴张文刘瑜宋海峰罗丽珠张政军赖新春 Science and Technology on Surface Physics and Chemistry Laboratory Department of Engineering Physics Tsinghua University Key Laboratory of Neutron Physics Institute of Nuclear Physics and ChemistryChina Academy of Engineering Physics Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Software Center for High Performance Numerical Simulation China Academy of Engineering Physics Key Laboratory of Advanced Materials (MOE) School of Materials Science and EngineeringTsinghua University

We have systematically studied the behaviors of the resistivity and magnetization of CeSb2 single crystals as a function of temperature and external field. Four anomalies in the resistivity/magnetization-versus-temperature curves are observed at low magnetic field. They are located at 15.5 K, 11.5 K, 9.5 K, and 6.5 K, corresponding to the paramagnetic–magnetically ordered state（MO）, MO-antiferromagnetic（AFM）, AFM–AFM, and AFM–ferromagnetic（FM） transitions, *** anomaly at 9.5 K is only visible with H‖[010] by magnetic susceptibility measurements, indicating that the AFM–AFM transition only happens along [010] direction in ab-plane. The four magnetic transitions are strongly suppressed by high external field. Finally, the field-temperature phase diagrams of CeSb2 with different orientations of the applied field in ab-plane are constructed and indicate the highly anisotropic nature of the magnetization of CeSb2.

关键词： CeSb2 electronic properties magnetic properties

来源：评论

学校读者我要写书评

暂无评论

Pulse Phase Modulation for On-Off Thruster Pair

Pulse Phase Modulation for On-Off Thruster Pair

引用

IEEE Aerospace Conference

作者： Runle Du Jiaqi Liu Li Zhang Lu Gao National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics

ISBN: (纸本)9781479916191

On-Off thrusters have limitation both at minimum on-time and minimum off-time, so the output is nonlinear pulses. Use on-off thrusters to provide linear or near linear control force is a fundamental and important research topic. Existing previous works do not overcome the limitation of on-time and off-time constraints, so the output is only an approximation of demanded force output. In this paper, Pulse Phase modulation (PP) is proposed to generate linear output through on-off thruster pair. PP modulation exploited the dynamic output curve of thrusters. By adjusting phase difference of thruster pair that installed in the opposite direction, thrust output can be linear proportional to demanded force output. PP modulation breaks the limitation caused by minimum on-time and off-time, and thus achieves high continuity of thrust output. For practical engineering implementation, two approximate methods are proposed as double frequency phase modulation and quadruple frequency phase modulation. Theoretical analysis and experimental results are provided to prove that PP modulation can yield much better precision in stabilizing space vehicles.

关键词： THRUSTER phase modulation on-off Punctuality phase difference Output off time Time constraints Polypropylenes Space vehicles Pairing

来源：评论

学校读者我要写书评

暂无评论

Suppressing the effects of ionospheric scintillation on geosynchronous SAR by optimised orbit design

Suppressing the effects of ionospheric scintillation on geos...

引用

2017 International Conference on Radar Systems, Radar 2017

作者： Li, YuanHao Liu, XiangRong Hu, Cheng Dong, XiChao School of Information and Electronics Beijing Institute of Technology 100081 China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics 100076 China Beijing Key Laboratory of Embedded Real-time information Processing Technology 100081 China

ISBN: (纸本)9781785615153

An L band geosynchronous synthetic aperture radar (GEO SAR) will be sensitive to ionosphere scintillation because of its low carrier frequency. Meanwhile, because of the high orbit, GEO SAR has a higher probability to meet ionospheric scintillation. In this paper, we propose an orbit strategy for eliminating the impacts of ionospheric scintillation. It is realized by selecting a proper orbit element (time past perigee) to avoid imaging for the sensitive region of ionospheric scintillation during the eruption time interval of ionospheric scintillation with the highest probability. Finally, the simulation based on systems tool kit (STK) software was conducted to verify the effectiveness of the method. © 2017 Institution of Engineering and technology. All rights reserved.

关键词： Synthetic aperture radar

来源：评论

学校读者我要写书评

暂无评论

Simulations of dissolved oxygen concentration in CMIP5 Earth system models

引用

Acta Oceanologica Sinica 2016年第12期35卷 28-37页

作者： BAO Ying LI Yangchun The First Institute of Oceanography State Oceanic Administration Laboratory for Regional Oceanography and Numerical Modeling Qingdao National Laboratory for Marine Science and Technology State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of Science

The climatologies of dissolved oxygen concentration in the ocean simulated by nine Earth system models(ESMs) from the historical emission driven experiment of CMIP5(Phase 5 of the Climate Model Intercomparison Project) are quantitatively evaluated by comparing the simulated oxygen to the WOA09 observation based on common statistical metrics. At the sea surface, distribution of dissolved oxygen is well simulated by all nine ESMs due to well-simulated sea surface temperature(SST), with both globally-averaged error and root mean square error(RMSE) close to zero, and both correlation coefficients and normalized standard deviation close to 1. However, the model performance differs from each other at the intermediate depth and deep ocean where important water masses exist. At the depth of 500 to 1 000 m where the oxygen minimum zones(OMZs) exist, all ESMs show a maximum of globally-averaged error and RMSE, and a minimum of the spatial correlation coefficient. In the ocean interior, the reason for model biases is complicated, and both the meridional overturning circulation(MOC) and the particulate organic carbon flux contribute to the biases of dissolved oxygen distribution. Analysis results show the physical bias contributes more. Simulation bias of important water masses such as North Atlantic Deep Water(NADW), Antarctic Bottom Water(AABW) and North Pacific Intermediate Water(NPIW) indicated by distributions of MOCs greatly affects the distributions of oxygen in north Atlantic, Southern Ocean and north Pacific, *** the model simulations of oxygen differ greatly from each other in the ocean interior, the multi-model mean shows a better agreement with the observation.

关键词： dissolved oxygen CMIP5 Earth system model meridional overturning circulation particulate organic carbon flux

来源：评论

学校读者我要写书评

暂无评论

The Design of Large Arc-shape High-precision Walking Device in TV(thermal-vacuum) Conditions

The Design of Large Arc-shape High-precision Walking Device ...

引用

2018 3rd International Conference on Design, Mechanical and Material Engineering (D2ME 2018)

作者： Xue Lian Nan Hua Liu Jiaqi Liu Xin Meng Gang National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics

The large-sized space environmental simulation test facility is mainly used for providing thermal radiation environment in high-vacuum,cold and dark space for satellites,spacecraft,lunar spacecraft to carry out whole satellite thermal vacuum test and for large equipment like antenna to carry out tests in TV *** the spacecraft's surface optical image or temperature is a main task in space environment simulation *** previous tests,optical image test mainly took place in a fixed position,so the measuring location and angle are *** paper focuses on large spherical space environmental simulation test facility,and designs a large arc-shape high-precision walking device in a space environment simulation test *** introduces key technology in detail like structure design,thermal design,processes and manufacturing,*** test results show that this device can work steadily and reliably under simulation space environments,and the precision exceeds 0.5.

关键词： thermal-vacuum Conditions The Design of Large Arc-shape High-precision Walking Device in TV Arc

来源：评论

学校读者我要写书评

暂无评论

Optimal Selection of regularization parameter for ?1-based image restoration based on SURE

Optimal Selection of regularization parameter for ?1-based i...

引用

International Symposium on Optoelectronic technology and Application 2016(OTA 2016)——Conf.12 Infrared technology and Application

作者： Feng Xue Xin Liu Hongyan Liu Jiaqi Liu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics

In real applications of infrared imaging and remote sensing, the observed images are often blurry and noisy due to the limitations of acquisition system. This degradation is often mathematically formu

关键词：

来源：评论

学校读者我要写书评

暂无评论

An Improved DSDV Protocol based on Link Stability with Adaptive Period for Intra-cluster Routing in High-dynamic Flying UAV Networks

An Improved DSDV Protocol based on Link Stability with Adapt...

引用

2022 International Applied Computational Electromagnetics Society Symposium, ACES-China 2022

作者： Zhang, Yiguo Qian, Lai Xue, Xiaoqin Wang, Wei Xi'an Polytechnic University College of Computer Science Xi'an China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing Institute of Space Long March Vehicle Beijing China

ISBN: (纸本)9781665452366

We propose a stability-based adaptive-period DSDV intra-cluster routing protocol that automatically adjusts the routing update period by the link stability among the nodes in the cluster structure, thus reducing the network overhead of the network structure in maintaining the routing table. We describe the link stability and adaptive period implementation and test the proposed routing protocol in the cluster structure based on network simulation. The implementation results show that the proposed routing protocol has better performance than the traditional DSDV routing protocol, can improve the network throughput and reduce the routing overhead in the network, and has good adaptability in the cluster with fast changing network topology. © 2022 IEEE.

关键词： Unmanned aerial vehicles (UAV)

来源：评论

学校读者我要写书评

暂无评论

Topology Optimization of Complex Network based on NSGA-II 4

Topology Optimization of Complex Network based on NSGA-II

引用

4th IEEE Advanced Information technology, Electronic and Automation Control Conference, IAEAC 2019

作者： Bin, Zhang Gan, Zhi-Chun Wen, Chen Hu, Qiang-Qiang Hou, Jian-Feng National University of Defense Technology Departments of Information and Communication China Science and Technology on Test Physics Numerical Mathematic Laboratory China

ISBN: (纸本)9781728119076

This paper proposes a complex network topology optimization method based on NSGA-II with degrees and edges number unchanged. The method selects the elite parent networks by applying non-dominated layer sorting and congestion degree calculation through the network crossover and mutation operation to achieve maximum network efficiency and network invulnerability. Simulation analysis shows that the method can significantly improve the invulnerability and network efficiency of the initial networks at the same time. Optimizing the network efficiency makes the network connection show a negative correlation. The network presents a "multi-core decentralized" structure;optimizing the network invulnerability makes the connection show a positive correlation, the network presents a "close core and scattered periphery" structure;the cooperative optimization makes the network present a "tighter core and large periphery" structure, which is proved with good theoretical generality and practical application value. © 2019 IEEE.

关键词： Complex networks

来源：评论

学校读者我要写书评

暂无评论

Research on Heterogeneous Parallel Algorithms for Radar Signal Processing in OpenCL Platform

Research on Heterogeneous Parallel Algorithms for Radar Sign...

引用

2022 International Applied Computational Electromagnetics Society Symposium, ACES-China 2022

作者： Wang, Yingfei Xue, Xiaoqin Wang, Wei Xi'an Polytechnic University Department of Computer Science Xi'an China Beijing Institute of Space Long March Vehicle National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (纸本)9781665452366

An efficient radar signal processing parallel algorithm for Open Computing Language (OpenCL) is presented in this paper, which reveals a rational allocation schema of tasks between the central processing unit (CPU) and the graphics processing unit (GPU). The powerful parallel processing ability of GPU is used to replace the traditional serial processing method by the way of pipeline acceleration and algorithm parallel acceleration, and the real-time performance of the proposed algorithm is improved by the design idea of intra-module parallelism and inter-module flow processing. The algorithm is applied to CPU-GPU heterogeneous computing platform and has a good portability. The effectiveness and real-time performance of the algorithm are verified through simulation data. © 2022 IEEE.

关键词： Graphics processing unit

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：