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Ballistic impact response of resistance-spot-welded(RSW) double-layered plates for Q&P980 steel

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Defence Technology（防务技术） 2022年第6期18卷 1052-1064页

作者： Bo-han ma Dong-fang ma Huan-ran Wang da-nian Chen Feng-hua Zhou MOE Key Laboratory of Impact and Safety Engineering Ningbo UniversityNingbo315211China College of Science&Technology Ningbo UniversityNingbo315211China

Ballistic impact response of resistance-spot-welded(RSW)double-layered(2×1.6 mm)plates(190 mm×150 mm)for Q&P980 steel impacted by a round-nosed steel bullet(12 mm diameter and 30 mm length)was investigated by using gas gun and high-speed camera system.The RSW specimens were spot welded using a 6 mm diameter electrode face producing a 7.2 mm diameter fusion zone of the spot weld.The ballistic curve and energy balance for the tests of the spot weld of the RSW specimens at different velocity were analyzed to characterize the ballistic behavior of the RSW specimens under bullet impact.The fracture mechanisms of the RSW specimens under bullet impact were presented.For the tests below the ballistic limit,the cracks initiated from the notch-tip and propagated along the faying surface or obliquely through the thickness depending on the impact velocity.For the tests above the ballistic limit,the plug fracture in the front plate of the RSW specimen could be caused by the thinning-induced necking in the BM near the HAZ,while the plug fracture in the rear plate of the RSW specimens may be consist of the circumferential cracking from the rear surface and the bending fracture of the hinged part of material.The effects of the electrode indentation and the weld interfaces on deformation and fracture of the RSW specimens under bullet impact were revealed.For the tests above the ballistic limit,the circumferential fracture from the rear surface of the RSW specimens was always initiated along the interior periphery of the electrode indentation and the crack paths were along the FZ/CGHAZ or CGHAZ/FGHAZ interface.When the circumferential crack also formed outside the electrode indentation,the fracture on the BM/HAZ interface could be found.On the front plate of the RSW specimens,the shear/bending induced cracking from the notch-tip were observed and the crack paths were along the FZ/CGHAZ or CGHAZ/FGHAZ interface.

关键词： RSW Q&P980 steel Ballistic impact Deformation Fracture

Ultra-stable and multistimuli-responsive nanoparticles coated with zwitterionic pillar[n]arene for enhanced cellular uptake

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Chinese Chemical Letters 2021年第3期32卷 1025-1028页

作者： Yupeng Jiao Shang Lan da ma Department of Chemistry Fudan UniversityShanghai 200433China

Nanoparticle surface property is crucial for circulation stability,cellullar uptake and other biological characteristics.Zwitte rionic pillar[n]arenes(ZPns)we re used to coat gold nanopa rticles(GNPs)via hostguest interaction.The resulting GNPs demonstrated higher stability in blood serum compared to polyethylene glycol(PEG)-coated GNPs.ZPn-coated GNPs were responsive to UV-irradiation,competitive displacement and acidic pH.UV-irradiation or competitive displacement could lead to the removal of ZPn coating to expose GNPs,which enhanced cell uptake efficiency by 5.9-and 7.4-fold,respectively.

关键词： Host-guest systems Stimuli responsiveness Zwitterionic ligands Gold nanoparticles Cellular uptake

Impurities analysis of high-purity osmium target for M-cathode application

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Rare Metals 2023年第4期42卷 1154-1159页

作者： Jun-da ma Yang Xia Yuan-Feng Xie Chao Zhang GRImaT Engineering Institute Co. LtdBeijing101407China State Key Laboratory of Advanced materials for Smart Sensing GRINM Group Co.LtdBeijing101407China General Research Institute for Nonferrous Metals Beijing100088China

Impurities and their distributions in osmium targets for M-type cathodes affect the coating quality on porous tungsten and cathode emission performance.Glow discharge mass spectrometry(GDMS)and X-ray photoelectron spectroscopy(XPS)were used to analyze the impurity contents and distributions in the osmium target.The chemical states of impurity elements were analyzed and characterized.The total amount of metallic impurity in the target was lower than 0.01 wt%.

关键词： osmium Impurities purity

What decarbonized the residential building operation worldwide since the 2000s

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Petroleum Science 2022年第6期19卷 3194-3208页

作者： Min-da ma Min-Xia Chen Wei Feng Jing-Wen Huo Building Technology&Urban Systems Division Lawrence Berkeley National LaboratoryBerkeleyCA 94720United States School of management Science and Real Estate Chongqing UniversityChongqing400045PR China Department of Earth System Science Tsinghua UniversityBeijing100084PR China

Decarbonization in operational residential buildings worldwide has become critical in achieving the carbon neutral target due to the growing household energy demand.To accelerate the pace of global carbon neutrality,this study explores the operational carbon change in global residential buildings through the generalized Divisia index method and decoupling analysis,considering the decarbonization levels of residential buildings at different scales.The results show that(1)most of the samples showed a decrease in the total emissions from 2000 to 2019.Except for China and the United States(US),the carbon emissions in global residential building operations decreased by 7.95 million tons of carbon dioxide(MtCO_(2))per year over the study period.Emissions per gross domestic product(GDP)was the most positive driver causing the decarbonization of residential buildings,while GDP was the most negative driver.(2)Carbon intensity was essential to achieving a strong decoupling of economic development and carbon emissions.The US almost consistently presented strong decoupling,while China showed weak decoupling over the last two decades.(3)The pace of decarbonization in global residential building operations is gradually slowing down.From 2000 to 2019,decarbonization from residential buildings across 30 countries was 2094.3 MtCO_(2),with a decarbonization efficiency of 3.4%.Overall,this study addresses gaps in evaluating global decarbonization from operational residential buildings and provides a reference for evaluating building decarbonization by other emitters.

关键词： Global residential building Operational decarbonization Generalized divisia index method Decoupling elasticity Building decarbonization strategies

Mesoscopic Modeling Approach and Application for Steel Fiber Reinforced Concrete under Dynamic Loading:A Review

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Engineering 2022年第9期16卷 220-238页

作者： Jinhua Zhang Zhangyu Wu Hongfa Yu Haiyan ma Bo da School of Civil Engineering Southeast UniversityNanjing 210096China Department of Civil and Airport Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Science and Technology on Near-Surface Detection Laboratory Wuxi 214035China College of Harbour Coastal and Offshore EngineeringHohai UniversityNanjing 210098China

Steel fiber reinforced concrete(SFRC)has drawn extensive attention in recent years for its superior mechanical response to dynamic and impact loadings.Based on the existing test results,the highstrength steel fibers embedded in a concrete matrix usually play a strong bridging effect to enhance the bonding force between fiber and the matrix,and directly contribute to the improvement of the post-cracking behavior and residual strength of SFRC.To gain a better understanding of the action behavior of steel fibers in matrix and further capture the failure mechanism of SFRC under dynamic loads,the mesoscopic modeling approach that assumes SFRC to be composed of different mesoscale phases(i.e.,steel fibers,coarse aggregates,mortar matrix,and interfacial transition zone(ITZ))has been widely employed to simulate the dynamic responses of SFRC material and structural members.This paper presents a comprehensive review of the state-of-the-art mesoscopic models and simulations for SFRC under dynamic loading.Generation approaches for the SFRC mesoscale model in the simulation works,including steel fiber,coarse aggregate,and the ITZ between them,are reviewed and compared systematically.The material models for different phases and the interaction relationship between fiber and concrete matrix are summarized comprehensively.Additionally,some example applications for SFRC under dynamic loads(i.e.,compression,tension,and contact blast)simulated using the general mesoscale models are given.Finally,some critical analysis on the current shortcomings of the mesoscale modeling of SFRC is highlighted,which is of great significance for the future investigation and development of SFRC.

关键词： Steel fiber reinforced concrete Mesoscale modeling Dynamic loading materials model Interfacial characteristic

A new correction method for quasi-Keplerian orbits

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Research in Astronomy and Astrophysics 2020年第11期20卷 191-204页

作者： Yue Chen da-Zhu ma Fang Xia Purple Mountain Observatory Chinese Academy of SciencesNanjing 210033China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China School of Information and Engineering Hubei Minzu UniversityEnshi 445000China

A pure two-body problem has seven integrals including the Kepler energy,the Laplace vector and the angular momentum vector.However,only five of them are independent.When the five independent integrals are preserved,the two other dependent integrals are naturally preserved from a theoretical viewpoint;but they may not necessarily be from a numerical computational viewpoint.Because of this,we use seven scale factors to adjust the integrated positions and velocities so that the adjusted solutions strictly satisfy the seven constraints.Noticing the existence of the two dependent integrals,we adopt the Newton iterative method combined with singular value decomposition to calculate these factors.This correction scheme can be applied to perturbed two-body and N-body problems in the solar system.In this case,the seven quantities associated with each planet slowly vary with time.More accurate values can be given to the seven slowly-varying quantities by integrating the integral invariant relations of these quantities and the equations of motion.They should be satisfied with the adjusted solutions.Numerical tests show that the new method can significantly reduce the rapid growth of numerical errors for all orbital elements.

关键词： Computational methods Computational astronomy planets and satellites dynamical

Performance Validation and Analysis for Multi-Method Fusion Based Image Quality Metrics in A New Image database

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China Communications 2019年第8期16卷 147-161页

作者： Xiaoyu ma Xiuhua Jiang da Pan Communication and Information Technology School Communication University of China

Considering that there is no single full reference image quality assessment method that could give the best performance in all situations, some multi-method fusion metrics were proposed. machine learning techniques are often involved in such multi-method fusion metrics so that its output would be more consistent with human visual perceptions. On the other hand, the robustness and generalization ability of these multi-method fusion metrics are questioned because of the scarce of images with mean opinion scores. In order to comprehensively validate whether or not the generalization ability of such multi-method fusion IQA metrics are satisfying, we construct a new image database which contains up to 60 reference images. The newly built image database is then used to test the generalization ability of different multi-method fusion IQA metrics. Cross database validation experiment indicates that in our new image database, the performances of all the multi-method fusion IQA metrics have no statistical significant different with some single-method IQA metrics such as FSIM and maD. In the end, a thorough analysis is given to explain why the performance of multi-method fusion IQA framework drop significantly in cross database validation.

关键词： full reference image quality assessment image database multi-method fusion

AND molecular logic gates based on host-guest complexation operational in live cells

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Chinese Chemical Letters 2022年第2期33卷 881-884页

作者： Siyang Jiang Weipeng mao dake mao Zhan-Ting Li da ma Department of Chemistry Fudan UniversityShanghaiShanghai 200433China College of Chemistry and Green Catalysis CenterZhengzhou UniversityZhengzhou 450001China

We report supramolecular AND logic gates based on host-guest complexation between acid-labile acyclic cucurbit[n]uril(CB[n]) molecular container and Na Cl O-responsive dye. Supramolecular AND logic gate is turned on due to acid-triggered degradation of molecular container and the release of the dye, followed by Na Cl O-induced fluorescence “switch on” effect of the dye. The reason for AND molecular logic gate is discovered to be the combination of oxidation inhibition and fluorescence “switch off” effect. Supramolecular AND logic gate is confirmed to be operational in live MCF-7 and He La cancer cells.

关键词： Host-guest chemistry Logic gate Stimuli-responsive systems Cucurbituril Bioimaging

Downlink Resource Allocation for NOma-Based Hybrid Spectrum Access in Cognitive Network

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中国通信:英文版 2023年第9期20卷 171-184页

作者： Yong Zhang Zhenjie Cheng da Guo Siyu Yuan Tengteng ma Zhenyu Zhang School of Electronic Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China Beijing Key Laboratory of Work Safety Intelligent Monitoring(Beijing University of Posts and Telecommunications) Beijing 100876China

To solve the contradiction between limited spectrum resources and increasing communication demand,this paper proposes a wireless resource allocation scheme based on the Deep Q Network(DQN)to allocate radio resources in a downlink multi-user cognitive radio(CR)network with slicing.Secondary users(SUs)are multiplexed using non-orthogonal multiple access(NOma).The SUs use the hybrid spectrum access mode to improve the spectral efficiency(SE).Considering the demand for multiple services,the enhanced mobile broadband(eMBB)slice and ultrareliable low-latency communication(URLLC)slice were established.The proposed scheme can maximize the SE while ensuring Quality of Service(QoS)for the users.This study established a mapping relationship between resource allocation and the DQN algorithm in the CR-NOma network.According to the signal-to-interference-plusnoise ratio(SINR)of the primary users(PUs),the proposed scheme can output the optimal channel selection and power allocation.The simulation results reveal that the proposed scheme can converge faster and obtain higher rewards compared with the Q-Learning scheme.Additionally,the proposed scheme has better SE than both the overlay and underlay only modes.

关键词： cognitive network network slicing non-orthogonal multiple access hybrid spectrum access resource allocation deep reinforcement learning