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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

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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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Reliability Analysis of Manufacturing Machine with Degradation and Low-quality Feedstocks

Reliability Analysis of Manufacturing Machine with Degradati...

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Advanced Reliability and Maintenance modeling (APARM), Asia-Pacific International Symposium on

作者： Zhenggeng Ye Zhiqiang Cai Hui Yang Department of Industrial Engineering Northwestern Polytechnical University Xi’an China School of Mechanical Engineering Northwestern Polytechnical University Xi’an P.R. China Ministry of Industry and Information Technology Key Laboratory of Industrial Engineering and Intelligent Manufacturing Northwestern Polytechnical University Xi’an P.R. China Complex Systems Monitoring Modeling and Control Laboratory in the Harold Pennsylvania State University (University Park) State College PA USA The Harold and Inge Marcus Department of Industrial and Manufacturing Engineering The Pennsylvania State University (University Park) State College USA Department of Industrial and Manufacturing Engineering Pennsylvania State University (University Park) State College PA USA

ISBN: (数字)9781728171029

ISBN: (纸本)9781728171036

Machine reliability is one major concern in manufacturing industries, which is affected by interior degradation and outside shocks simultaneously. Low-quality feedstocks, as one typical kind of shocks, may arrive randomly during the operation of a machine. However, due to the instability of environment and manufacturing factors, low-quality feedstocks may arrive in clusters in some specific batches. In this paper, we first proposed a reliability evaluation model for the repairable machine, accounting for machine degradation and shocks caused by low-quality feedstocks. Then, the cluster arrival of low-quality feedstocks is modeled by the Hawkes point process with the properties of self-exciting and history dependent. Moreover, considering the degradation and shocks, the mixture failure rate of a machine is modeled. Further, the expectation of remaining lifetime is derived. Finally, the simulation experiment is implemented to compare the performance between the machine when the arrival intervals of low-quality feedstocks follow the Poisson point process and the Hawkes point process. Experimental results show the effectiveness of the proposed model for machine reliability analysis.

关键词： Electric shock Degradation Maintenance engineering Mathematical model Manufacturing Reliability engineering

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DeepFlame: A deep learning empowered open-source platform for reacting flow simulations

arXiv

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arXiv 2022年

作者： Mao, Runze Lin, Minqi Zhang, Yan Zhang, Tianhan John Xu, Zhi-Qin Chen, Zhi X. State Key Laboratory of Turbulence and Complex Systems Aeronautics and Astronautics College of Engineering Peking University Beijing100871 China Ai for Science Institute Beijing100080 China Caep Software Center for High Performance Numerical Simulation Beijing100088 China Institute of Applied Physics and Computational Mathematics Beijing100088 China Department of Mechanics and Aerospace Engineering SUSTech Shenzhen518055 China Institute of Natural Sciences School of Mathematical Sciences Shanghai Jiao Tong University Shanghai200240 China MOE-LSC Qing Yuan Research Institute Shanghai Jiao Tong University Shanghai200240 China

Recent developments in deep learning have brought many inspirations for the scientific computing community and it is perceived as a promising method in accelerating the computationally demanding reacting flow simulations. In this work, we introduce DeepFlame, an open-source C++ platform with the capabilities of utilising machine learning algorithms and pre-trained models to solve for reactive flows. We combine the individual strengths of the computational fluid dynamics library OpenFOAM, machine learning framework Torch, and chemical kinetics program Cantera. The complexity of cross-library function and data interfacing (the core of DeepFlame) is minimised to achieve a simple and clear workflow for code maintenance, extension and upgrading. As a demonstration, we apply our recent work on deep learning for predicting chemical kinetics (Zhang et al. Combust. Flame vol. 245 pp. 112319, 2022) to highlight the potential of machine learning in accelerating reacting flow simulation. A thorough code validation is conducted via a broad range of canonical cases to assess its accuracy and efficiency. The results demonstrate that the convection-diffusion-reaction algorithms implemented in DeepFlame are robust and accurate for both steady-state and transient processes. In addition, a number of methods aiming to further improve the computational efficiency, e.g. dynamic load balancing and adaptive mesh refinement, are explored. Their performances are also evaluated and reported. With the deep learning method implemented in this work, a speed-up of two orders of magnitude is achieved in a simple hydrogen ignition case when performed on a medium-end graphics processing unit (GPU). Further gain in computational efficiency is expected for hydrocarbon and other complex fuels. A similar level of acceleration is obtained on an AI-specific chip - deep computing unit (DCU), highlighting the potential of DeepFlame in leveraging the next-generation computing architecture and hardware. © 202

关键词： Graphics processing unit

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The ${ {\bar{\boldsymbol q}\boldsymbol q\bar{\boldsymbol s}\boldsymbol Q} \;\;{(\boldsymbol q {\bf =}\boldsymbol u,\,\boldsymbol d;\,\boldsymbol Q{\bf =}\boldsymbol c,\,\boldsymbol b)} }$ tetraquark system in a chiral quark model*

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Chinese Physics C 2024年第7期48卷 073106-073106页

作者： Gang Yang Jialun Ping Jorge Segovia Department of Physics Zhejiang Normal University Jinhua 321004 China Department of Physics and Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems Nanjing Normal University Nanjing 210023 China Departamento de Sistemas Físicos Químicos y Naturales Universidad Pablo de Olavide E-41013 Sevilla Spain

The S-wave $\bar{q}q\bar{s}Q \;\; (q=u,\,d;\,Q=c,\,b)$ tetraquarks, with spin-parities $J^P=0^+$, $1^+$, and $2^+$, in both isoscalar and isovector sectors, are systematically studied using a chiral quark model. The

The S-wave $\bar{q}q\bar{s}Q \;\; (q=u,\,d;\,Q=c,\,b)$ $\bar{q}q\bar{s}Q \;\; (q=u,\,d;\,Q=c,\,b)$ tetraquarks, with spin-parities $ J^P=0^+ $ $J^P=0^+$, $ 1^+ $ $1^+$, and $ 2^+ $ $2^+$, in both isoscalar and isovector sectors, are systematically studied using a chiral quark model. The

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Impact of Ligand Fields on Kubas Interaction of Open Copper Sites in Mofs with Hydrogen Molecules: An Electronic Structural Insight

SSRN

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SSRN 2024年

作者： Nguyen-Thuy, Trang Tran-Van, Hoan Nguyen-Hoang, Linh Nguyen-Minh, Hoang Phan, Bach Thang Nguyen-The, Toan Kawazoe, Yoshiyuki Faculty of physics University of Science Vietnam National University – Hanoi Hanoi Viet Nam School of engineering physics Hanoi University of Technology Hanoi Viet Nam Center for Innovative Materials and Architectures Vietnam National University Ho Chi Minh City Ho Chi Minh City Viet Nam Vietnam National University HoChiMinh City Viet Nam Key Laboratory for Multiscale Simulation of Complex Systems University of Science Vietnam National University – Hanoi Hanoi Viet Nam New Industry Creation Hatchery Center Tohoku University Sendai980-8579 Japan Department of Physics and Nanotechnology SRM Institute of Science and Technology Tamil Nadu Kattankulathur603203 India School of Physics Institute of Science Suranaree University of Technology 111 University Avenue Nakhon Ratchasima30000 Thailand

Using DFT calculations, we investigate hydrogen sorption on open copper sites in various ligand coordinations of metal-organic frameworks (MOFs), including the triangle coordination T(CuL3) in MFU-4l, the linear coordination L(CuL2) in NU2100 and the paddlewheel coordination P(CuL4)2 in HKUST-1. By examining the ligand field splitting of d states and spd hybridizations in copper, we reveal the electronic mechanisms influencing hydrogen sorption performance. Despite Cu+ oxidization state which is expected to facilitate strong Kubas interaction with hydrogen molecules, the vacant s-p-dz2 hybrid orbitals of the open copper site in the L(CuL2) coordination are unsuitable for overlapping with the H2 s bonding orbital, preventing hydrogen adsorption. In contrast, the T(CuL3) and P(CuL4)2 coordinations enable hydrogen adsorption by inducing suitable hydrid orbitals. The vacant Cu s-p-dz2 hybrid orbitals in these cases can overlap with the H2 s bonding orbital to facilitate electron forward donation, forming bonding states between the Cu s-p-dz2 and H2 s bonding orbitals. The occupied Cu s-p-dxz/yz and s-p-dx2-y2 hybrid orbitals in the case of T(CuL3) promote the electron back donation to the H2 s* antibonding orbital, leading to the formation of bonding states. Conversely, in P(CuL4)2 coordination, the absence of such hybridization results in the lack of electron back donation. The complete Kubas interaction with both forward and back electron donations is responsible for a higher adsorption energy of 37.6 kJ/mol in the case of T(CuL3) than the value of 10.6 kJ/mol in the P(CuL4)2 coordination. © 2024, The Authors. All rights reserved.

关键词： Electronic structure

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Grand−canonical Monte−Carlo simulation of DNA condensation in equilibrium with a salt mixture containing 2:2 salt

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Journal of Physics: Conference Series 2017年第1期865卷

作者： Nguyen V Duc Toan T Nguyen Faculty of Physics VNU University of Science Vietnam National University 334 Nguyen Trai Street Thanh Xuan Hanoi Vietnam VNU Key Laboratory for Multiscale Simulation of Complex Systems Vietnam National University 334 Nguyen Trai Street Thanh Xuan Hanoi Vietnam School of Physics Georgia Institute of Technology 837 State Street Atlanta Georgia 30332-0430 USA

The Grand–canonical Monte–Carlo simulation method is used to simulate DNA hexagonal condensate in the presence of a mixture of 1:1, 2:1, 2:2 salts using the primitive ion model. Previous results show that DNA can be condensed by divalent counterions in restricted environment, such as inside viruses. In this work, we study the effects of divalent co-ions on condensation of DNA by divalent counterions. It is shown that divalent co–ions lead to weaker DNA condensation free energy and DNA de–condensation at smaller counterions concentration.

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Overview of the South China Sea Monsoon Experiment

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Advances in Atmospheric Sciences 2004年第3期21卷 343-360页

作者：丁一汇李崇银柳艳菊 National Climate Center China Meteorological Administration Beijing 100081 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 National Climate Center China Meteorological Administration Beijing 100081 State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid DynamicsInstitute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029he present paper gives an overview of the key project " South China Sea Monsoon Experiment (SCSMEX)" operated by the Ministry of Science and Technology of China during the period of 1996-2001. The SCSMEX is a joint atmospheric and oceanic field experiment which aims to better understand the onset maintenance and variability of the summer monsoon over the South China Sea (SCS). It is a large-scale international effort with many participating countries and regions cooperatively involved in this experiment. With the field observation in May-August 1998 a large amount of meteorological and oceanic data was acquired which provides excellent datasets for the study of the SCS monsoon and the East Asian monsoon and their interaction with the ocean. The preliminary research achievements are as follows. (1) The earliest onset of the Asian monsoon over the SCS and Indo-China Peninsula has been well documented. Prom the viewpoint of the synoptic process its onset is closely related to the early rapid development of a twin cyclone to the east of Sri Lanka. The conceptual modei of the SCS monsoon onset in 1998 was put forward. The 50-year time series of the SCS monsoon onset date was also made. (2) Two major modes namely the 30-60-day and 10-20-day oscillations were ascertained. The influences of the abnormal SCS monsoon on the precipitation over eastern China and its modes were identifled. A strong (weak) monsoon over the SCS usually leads to less (more) precipitation over the middle and lower reaches of the Yangtze River

The present paper gives an overview of the key project ' South China Sea Monsoon Experiment (SCSMEX)' operated by the Ministry of Science and Technology of China during the period of 1996-2001. The SCSMEX is a joint atmospheric and oceanic field experiment which aims to better understand the onset, maintenance, and variability of the summer monsoon over the South China Sea (SCS). It is a large-scale international effort with many participating countries and regions cooperatively involved in this experiment. With the field observation in May-August 1998, a large amount of meteorological and oceanic data was acquired, which provides excellent datasets for the study of the SCS monsoon and the East Asian monsoon and their interaction with the ocean. The preliminary research achievements are as follows. (1) The earliest onset of the Asian monsoon over the SCS and Indo-China Peninsula has been well documented. Prom the viewpoint of the synoptic process, its onset is closely related to the early rapid development of a twin cyclone to the east of Sri Lanka. The conceptual modei of the SCS monsoon onset in 1998 was put forward. The 50-year time series of the SCS monsoon onset date was also made. (2) Two major modes, namely the 30-60-day and 10-20-day oscillations were ascertained. The influences of the abnormal SCS monsoon on the precipitation over eastern China and its modes were identifled. A strong (weak) monsoon over the SCS usually leads to less (more) precipitation over the middle and lower reaches of the Yangtze River basin, and more (less) precipitation in North China. (3) During the monsoon onset over the SCS, a wide variety of organized mesoscale convective systems (MCSs) were observed by a Doppler radar array deployed over the northern SCS. The relationship between large-scale circulations and MCSs during the monsoon onset process in 1998 was clearly revealed. It was suggested that there is a kind of positive feedback mechanism between large-scale circulations and

关键词： field experiment South China Sea monsoon low frequency oscillation (LFO) meso scale convective systems (MSCs) air-sea interaction numerical simulation

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TOMAHAWK NITROGEN PRESSURIZATION MAINTENANCE - WHY

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NAVAL ENGINEERS JOURNAL 1993年第2期105卷 66-68页

作者： CIARULA, TA NERADKA, VF Cdr. Thomas A. Ciarula: USN was born in Pottstown Pa. He attended Northrop University in Inglewood Calif. where he earned a bachelor of science degree in aircraft maintenance engineering in September 1971. He was selected for Officer Candidate School where he was commissioned an ensign (Aeronautical Maintenance Duty) in August 1972. Cdr. Ciarula has been assigned to VA-37 The AIMD at NAF Kadena Okinawa Japan VXE-6 and the USS Forrestal. He was the wing maintenance for training officer for Air Wing Three at NAS Chase Field in Beeville Tex. and the AIMD officer at NAS Key West Fla. In 1988 Cdr. Ciarula was assigned to the Cruise Missiles Project (PEO-CU) where he was the TASM class desk officer and the director of logistics. While at the Cruise Missiles Project he was awarded his master of science in general administration from Central Michigan University. He is currently assigned to PMA-205 in the Naval Air Systems Command. Vincent F. Neradka:received B.S. and M.S. degrees from the University of Maryland in aerospace engineering in 1964 and 1969 and an MS in technical management from the Johns Hopkins University in 1986. He joined the Johns Hopkins University Applied Physics Laboratory in 1979 working on the Vertical Launching System of the Aegis cruisers. Since that time he has participated in activities on the Phalanx program the SPS-48E radar and long term involvement with the Cruise Missile Program. On the Cruise Missile Program Mr. Neradka has focused on the specification of and testing related to environments. Simulation activities have included modeling of pneumatic systems and NASTRAN dynamic modeling. Mr. Neradka is a registered professional engineer.

This paper discusses the data that were recorded during a three-month accelerated humidity test of two Tomahawk all-up rounds (AURs), one pressurized with dry nitrogen in accordance with the current practice, and the other left unpressurized. Temperature and humidity were recorded inside the canisters and missiles. Data analysis consisted of psychrometric calculations to determine the moisture intrusion into these missiles during the test. The work was carried out in support of a technical effort directed at changing the storage and stowage environmental protection of the Tomahawk missile.

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A Metal–Sulfur–Carbon Catalyst Mimicking the Two-Component Architecture of Nitrogenase

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Angewandte Chemie 2024年第45期136卷

作者： Junkai Xia Jiawei Xu Prof. Bing Yu Xiao Liang Dr. Zhen Qiu Prof. Hao Li Prof. Huajun Feng Prof. Yongfu Li Prof. Yanjiang Cai Prof. Haiyan Wei Prof. Haitao Li Prof. Hai Xiang Dr. Zechao Zhuang Prof. Dingsheng Wang State Key Laboratory of Subtropical Silviculture Zhejiang A&F University 311300 Hangzhou P. R. China College of Environment and Resources College of Carbon Neutrality Zhejiang A&F University 311300 Hangzhou P. R. China Jiangsu Key Laboratory of Numerical Simulation of Large Scale Complex Systems and School of Chemistry and Materials Science Nanjing Normal University 210023 Nanjing China Department of Chemistry Tsinghua University 100084 Beijing P. R. China Advanced Institute for Materials Research (WPI-AIMR) Tohoku University 980-8577 Sendai Japan Institute for Energy Research Jiangsu University 212013 Zhenjiang P. R. China Department of Chemical Engineering Columbia University 10027 New York NY USA

The production of ammonia (NH 3 ) from nitrogen sources involves competitive adsorption of different intermediates and multiple electron and proton transfers, presenting grand challenges in catalyst design. In nature nitrogenases reduce dinitrogen to NH 3 using two component proteins, in which electrons and protons are delivered from Fe protein to the active site in MoFe protein for transfer to the bound N 2 . We draw inspiration from this structural enzymology, and design a two-component metal–sulfur–carbon (M−S−C) catalyst composed of sulfur-doped carbon-supported ruthenium (Ru) single atoms (SAs) and nanoparticles (NPs) for the electrochemical reduction of nitrate (NO 3 − ) to NH 3 . The catalyst demonstrates a remarkable NH 3 yield rate of ~37 mg L −1 h −1 and a Faradaic efficiency of ~97 % for over 200 hours, outperforming those consisting solely of SAs or NPs, and even surpassing most reported electrocatalysts. Our experimental and theoretical investigations reveal the critical role of Ru SAs with the coordination of S in promoting the formation of the HONO intermediate and the subsequent reduction reaction over the NP-surface nearby. Such process results in a more energetically accessible pathway for NO 3 − reduction on Ru NPs co-existing with SAs. This study proves a better understanding of how M−S−Cs act as a synthetic nitrogenase mimic during ammonia synthesis, and contributes to the future mechanism-based catalyst design.

关键词： nitrogenase metal–sulfur–carbon nitrate reduction reaction ammonia synthesis synergistic interactions

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