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arXiv 2020年

作者： Wang, Guojun Wu, Jian Tian, Bin Teng, Siyu Chen, Long Cao, Dongpu The State Key Laboratory of Automotive Simulation and Control Jilin University Changchun130022 China The State Key Laboratory of Management and Control for Complex Systems Institute of Automation Chinese Academy of Sciences Beijing100190 China The School of Artificial Intelligence University of Chinese Academy of Sciences Beijing100190 China The Department of Computer Science Hong Kong Baptist University Hong Kong The School of Data and Computer Science Sun Yat-Sen University Guangdong Guangzhou510275 China The Department of Mechanical and Mechatronics Engineering University of Waterloo WaterlooONN2L 3G1 Canada

Accurate and fast 3D object detection from point clouds is a key task in autonomous driving. Existing one-stage 3D object detection methods can achieve real-time performance, however, they are dominated by anchor-based detectors which are inefficient and require additional post-processing. In this paper, we eliminate anchors and model an object as a single point-the center point of its bounding box. Based on the center point, we propose an anchor-free CenterNet3D network that performs 3D object detection without anchors. Our CenterNet3D uses keypoint estimation to find center points and directly regresses 3D bounding boxes. However, because inherent sparsity of point clouds, 3D object center points are likely to be in empty space which makes it difficult to estimate accurate boundaries. To solve this issue, we propose an extra corner attention module to enforce the CNN backbone to pay more attention to object boundaries. Besides, considering that one-stage detectors suffer from the discordance between the predicted bounding boxes and corresponding classification confidences, we develop an efficient keypoint-sensitive warping operation to align the confidences to the predicted bounding boxes. Our proposed CenterNet3D is non-maximum suppression free which makes it more efficient and simpler. We evaluate CenterNet3D on the widely used KITTI dataset and more challenging nuScenes dataset. Our method outperforms all state-of-the-art anchor-based one-stage methods and has comparable performance to two-stage methods as well. It has an inference speed of 20 FPS and achieves the best speed and accuracy trade-off. Our source code will be released at https://***/wangguojun2018/CenterNet3d. Copyright © 2020, The Authors. All rights reserved.

关键词： Autonomous vehicles

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黏弹性溶剂中胶体流变行为的多粒子碰撞动力学模拟

黏弹性溶剂中胶体流变行为的多粒子碰撞动力学模拟

引用

中国化学会2014年大分子体系理论、模拟与计算研讨会

作者：纪仕辰张晓佳 Roland G.Winkler Gerhard Gompper Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources School of Chemistry and Chemical EngineeringGuangxi Normal University Theoretical Soft Matter and Biophysics Institute of Complex Systems and Institute for Advanced SimulationForschungszentrum JülichD-52425 JülichGermany

以高分子等黏弹性溶剂为分散介质的胶体体系在新型功能材料研发等领域有着广泛的应用。实验表明,外加流场可以诱导黏弹性溶剂中的胶体自组装形成链状、层状等有序结构1,2,然而其机理及动力学过程仍不清晰。多粒子碰撞动力学模拟(MPC)是... 详细信息

以高分子等黏弹性溶剂为分散介质的胶体体系在新型功能材料研发等领域有着广泛的应用。实验表明,外加流场可以诱导黏弹性溶剂中的胶体自组装形成链状、层状等有序结构1,2,然而其机理及动力学过程仍不清晰。多粒子碰撞动力学模拟(MPC)是一种新兴的模拟方法,同时考虑了流体力学相互作用和热涨落,具有模拟效率高的优点,被广泛用来研究软物质体系3。我们将MPC模拟的溶剂粒子连接为dumbbell,研究表明dumbbell是一种高效的黏弹性溶剂4。进而我们考察了单个胶体粒子以及两个胶体粒子在流场下的运动。发现黏弹性溶剂中,单个胶体粒子的转动速率要慢于牛顿流体中。两个胶体的相对运动轨迹与单个胶体周围的流线相近。胶体的两体作用是多体作用的基础,我们的模拟有助于更好的理解胶体在黏弹性溶剂中的组装行为。

关键词：多粒子碰撞动力学黏弹性流变行为

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Study ofBs⟶ϕℓ+ℓ−Decays in the PQCD Factorization Approach with Lattice QCD Input

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Advances in High Energy Physics 2021年第1期2021卷

作者： Su-Ping Jin Zhen-Jun Xiao Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing Jiangsu 210023 *** Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 ***

In this paper, we studied systematically the semileptonic decays B s ⟶ ϕ l + l − with l − = ( e − , μ − , τ − ) by using the perturbative QCD (PQCD) and the “PQCD+Lattice” factorization approach, respectively. We first evaluated all relevant form factors F i ( q 2 ) in the low- q 2 region using the PQCD approach, and we also took the available lattice QCD results at the high- q 2 region as additional input to improve the extrapolation of F i ( q 2 ) from the low- q 2 region to the endpoint . We then calculated the branching ratios and many other physical observables , , S 3,4,7 , and A 5,6,8,9 and the clean angular observables P 1,2,3 and . From our studies, we find the following points: (a) the PQCD and “PQCD+Lattice” predictions of are about 7 × 10 −7 , which agree well with the LHCb measured values and the QCD sum rule prediction within still large errors; (b) we defined and calculated the ratios of the branching ratios and ; (c) the PQCD and “PQCD+Lattice” predictions of the longitudinal polarization F L , the CP-averaged angular coefficients S 3,4,7 , and the CP asymmetry angular coefficients A 5,6,8,9 agree with the LHCb measurements in all considered bins within the still large experimental errors; and (d) for those currently still unknown observables , and , we suggest LHCb and Belle-II Collaboration to measure them in their experiments.

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Charged AdS black hole and the quantum tunneling from black hole to white hole

arXiv

引用

arXiv 2022年

作者： Phat, T.H. Anh, N.T. Nguyen, Toan T. Quyet, H.V. Vietnam Atomic Energy Commission 59 Ly Thuong Kiet Hanoi Viet Nam Faculty of Energy Technology Electric Power University 235 Hoang Quoc Viet Hanoi Viet Nam Key Laboratory for Multiscale Simulation of Complex Systems Department of Theoretical Physics University of Science Vietnam National University − Hanoi 334 Nguyen Trai street Thanh Xuan Hanoi100000 Viet Nam Department of Physics Hanoi Pedagogical University 2 Vinh Phuc Phuc Yen15000 Viet Nam

In this paper, we show that depending on the sign of the electric charge Q, the charged AdS black hole (BH) possesses two alternative facets when the cosmological constant is identified to the thermodynamic pressure P. It is discovered that: 1) the equation of state of BH corresponds to Q > 0 and when Q changes from Q > 0 to Q WH (T) which releases in this process equals with minus sign the latent heat of BH, too;3) Finally, the probability of the quantum tunneling from the BH to the WH is obtained. We suggest the perspective of application of the results above to the AdS/CFT duality. Copyright © 2022, The Authors. All rights reserved.

关键词： Gravitation

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Option to survive or surrender: Carbon asset management and optimization in thermal power enterprises from China

arXiv

引用

arXiv 2021年

作者： Liu, Yue Tian, Lixin Xie, Zhuyun Zhen, Zaili Sun, Huaping School of Geography Nanjing Normal University Nanjing Jiangsu210042 China School of Finance and Economics Jiangsu University Zhenjiang Jiangsu212013 China Energy Development and Environmental Protection Strategy Research Center Jiangsu University Zhenjiang Jiangsu212013 China Energy Interdependency Behavior and Strategy Research Center School of Mathematical Science Nanjing Normal University Nanjing Jiangsu210042 China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing Jiangsu210042 China

Carbon emission right allowance is a double-edged sword, one edge is to reduce emission as its original design intention, another edge has in practice slain many less developed coal-consuming enterprises, especially for those in thermal power industry. Partially governed on the hilt in hands of the authority, body of this sword is the prices of carbon emission right. How should the thermal power plants dance on the blade motivates this research. Considering the impact of price fluctuations of carbon emission right allowance, we investigate the operation of Chinese thermal power plant by modeling the decision-making with optimal stopping problem, which is established on the stochastic environment with carbon emission allowance price process simulated by geometric Brownian motion. Under the overall goal of maximizing the ultimate profitability, the optimal stopping indicates the timing of suspend or halt of production, hence the optimal stopping boundary curve implies the edge of life and death with regard to this enterprise. Applying this methodology, real cases of failure and survival of several Chinese representative thermal power plants were analyzed to explore the industry ecotope, which leads to the findings that: 1) The survival environment of existed thermal power plants becomes severer when facing more pressure from the newborn carbon-finance market. 2) Boundaries of survival environment is mainly drawn by the technical improvements for rising the utilization rate of carbon emission. Based on the same optimal stopping model, outlook of this industry is drawn with a demarcation surface defining the vivosphere of thermal power plants with different levels of profitability. This finding provides benchmarks for those enterprises struggling for survival and policy makers scheming better supervision and necessary intervene. © 2021, CC BY-NC-SA.

关键词： Carbon

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Generation of orthogonal curvilinear grids on the sphere surface based on Laplace-Beltrami equations

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IOP Conference Series: Earth and Environmental Science 2014年第1期19卷

作者： Fuqiang Lu Zhiyao Song Xin Fang Key Laboratory of Virtual Geographic Environment (Ministry of Education) Nanjing Normal UniversityNanjing Jiangsu Province 210046 China AA(Jiangsu Provincial Key Laboratory for Numerical Simulation of Large Scale Complex Systems School of Mathematical Sciences Nanjing Normal University Nanjing 210046 China

In this paper, Laplace-Beltrami equations are used to generate orthogonal curvilinear grids on the sphere for ocean models. In addition to overcoming the pole-problem, the grid configuration has quasi-uniform cell-size on the whole sphere. Some quantities such as the grid length along two directions, the angle deviation from orthogonality, the area of the cell to evaluate the quality of the grid, which demonstrate the grid produced is fit to be a model grid on which the finite difference method or finite volume method can be implemented for numerical simulating of global atmosphere and ocean dynamics on large scale.

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Calibration and Modelling of Vegetation Structure Parameter B for L-Meb Models Over Agricultural Sites

SSRN

引用

SSRN 2024年

作者： Zhang, Hui Wang, Hongquan Sun, Zhibin Gao, Lun Wang, Yixiang Tong, Cheng Zhu, Luyao Shi, Zhou Institute of Agricultural Remote Sensing and Information Technology Application College of Environmental and Resource Sciences Zhejiang University Hangzhou310058 China Agriculture and Agri-Food Canada Lethbridge Research and Development Centre LethbridgeAB Canada Jiangsu Key Laboratory for Numerical Simulation of Large-Scale Complex Systems Nanjing Normal University Nanjing210023 China Agroecosystem Sustainability Center Institute for Sustainability Energy and Environment the University of Illinois at Urbana-Champaign UrbanaIL61801 United States State Key Laboratory of Subtropical Silviculture Zhejiang A&F University Hangzhou311300 China Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration of Zhejiang Province Zhejiang A&F University Hangzhou311300 China College of Environment and Resource Sciences Zhejiang A&F University Lin’an Zhejiang311300 China Research Institute for Urban Planning and Sustainability Hangzhou City University Hangzhou310015 China Key Laboratory of Spectroscopy Sensing Ministry of Agriculture Hangzhou310058 China

Passive microwave observations of vegetation water content (VWC) are important to monitor vegetation growth status and terrestrial aboveground biomass. To constrain the L-band Microwave Emission of the Biosphere (L-MEB) model for NASA’s Soil Moisture Active Passive (SMAP) satellite mission, vegetation structure parameter b is often used to estimate VWC from the climatological Normalized Difference Vegetation Index (NDVI). However, little is known about what and how the driving factors impact the parameter b and its modeling due to the lack of quantitative analysis. Based on the Passive Active L-band Sensor (PALS) data from the SMAPVEX16-MB campaign, this study firstly calibrated the parameter b for canola, wheat and soybean. Afterwards, a Random Forest algorithm was employed to model b-values using both h and v polarized observations with the input features screened by correlation analysis and stepwise regression for each vegetation type, the R2 of which exceeds 82%. Considering the poor interpretability of machine learning algorithms, we also employed multivariable-linear regression to quantify their influence on b-values and achieved an R2 exceeding 75%. The results showed all three crop types had an increasing trend in b-values at dual-polarization with their growth, except for wheat which exhibited a decreasing trend at v-polarization. Among the three crops, wheat and soybean indicated sharp changes in b-values, particularly during the late growth stage, while canola exhibited slower changes. The b-values were higher at v-polarization than at h-polarization, except for wheat during the early growth stage and at the end of the late growth stage. The results of multivariable regression with vegetation type as dummy variables (soybean as the control) indicated that crop type significantly affected b values, with canola and wheat exhibiting positive effects on b-values at h-polarization but negative effects at v-polarization. Additionally, we found that VWC, biomass

关键词： Polarization

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Streaming Algorithms for the k-Submodular Cover Problem

arXiv

引用

arXiv 2023年

作者： Wang, Wenqi Gutin, Gregory Mao, Yaping Du, Donglei Zhang, Xiaoyan School of Mathematical Science Institute of Mathematics Nanjing Normal University Key Laboratory of Ministry of Education Numerical Simulation of Large Scale Complex Systems Nanjing210023 China Royal Holloway University of London Egham SurreyTW20 0EX United Kingdom School of Mathematics and Statistics Academy of Plateau Science and Sustainability Qinghai Normal University Qinghai Xining810008 China Faculty of Management University of New Brunswick FrederictonNBE3B9Y2 Canada

Given a natural number k ≥ 2, we consider the k-submodular cover problem (k-SC). The objective is to find a minimum cost subset of a ground set X subject to the value of a k-submodular utility function being at least a certain predetermined value τ. For this problem, we design a bicriteria algorithm with a cost at most O(1/ǫ) times the optimal value, while the utility is at least (1 − ǫ)τ/r, where r depends on the monotonicity of g. © 2023, CC BY.

关键词： Approximation algorithms

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Effects of surface charge and environmental factors on the electrostatic interaction of fiber with virus-like particle: A case of coronavirus

arXiv

引用

arXiv 2021年

作者： Dung, Dinh Ngoc Phan, Anh D. Nguyen, Toan T. Lam, Vu D. Faculty of Materials Science and Engineering Phenikaa University Yen Nghia Ha Dong Ha Noi12116 Viet Nam Phenikaa Institute for Advanced Study Phenikaa University Yen Nghia Ha Dong Ha Noi12116 Viet Nam Key Laboratory for Multiscale Simulation of Complex Systems Faculty of Physics VNU University of Science Vietnam National University – Hanoi 334 Nguyen Trai Street Thanh Xuan District Hanoi10000 Viet Nam Graduate University of Science and Technology Vietnam Academy of Science and Technology 18 Hoang Quoc Viet Hanoi Viet Nam

We propose a theoretical model to elucidate intermolecular electrostatic interactions between a virus and a substrate. Our model treats the virus as a homogeneous particle having surface charge and the polymer fiber of the respirator as a charged plane. Electric potentials surrounding the virus and fiber are influenced by the surface charge distribution of the virus. We use Poisson-Boltzmann equations to calculate electric potentials. Then, Derjaguin’s approximation and a linear superposition of the potential function are extended to determine the electrostatic force. In this work, we apply this model for coronavirus or SARS-CoV-2 case and numerical results quantitatively agree with prior simulation. We find that the influence of fiber’s potential on the surface charge of the virus is important and is considered in interaction calculations to obtain better accuracy. The electrostatic interaction significantly decays with increasing separation distance, and this curve becomes steeper when adding more salt. Although the interaction force increases with heating, one can observe the repulsive-attractive transition when the environment is acidic. Copyright © 2021, The Authors. All rights reserved.

关键词： Boltzmann equation

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Erratum: Chiral phase and quantum phase transitions of anisotropic XY chains with three-site interactions

引用

Journal of Statistical Mechanics: Theory and Experiment 2012年第11期2012卷

作者： Xiaoxian Liu Ming Zhong Hui Xu Peiqing Tong Department of Physics and Institute of Theoretical Physics Nanjing Normal University Nanjing 210046 People's Republic of China Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210046 People's Republic of China

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