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Reactive molecular dynamics insight into the thermal decomposition mechanism of 2,6-Bis(picrylamino)-3,5-dinitropyridine

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Defence Technology（防务技术） 2024年第3期33卷 134-146页

作者： Jianbo fu Hui Ren Xinzhou Wu Yongjin chen Mi Zhang Yazhi cheng State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

2,6-bis(picrylamino)-3,5-dinitropyridine(PYX)has excellent thermostability,which makes its thermal decomposition mechanism receive much *** this paper,the mechanism of PYX thermal decomposition was investigated thoroughly by the ReaxFF-lg force field combined with DFT-B3LYP(6-311++G)*** detailed decomposition mechanism,small-molecule product evolution,and cluster evolution of PYX were mainly *** the initial stage of decomposition,the intramolecular hydrogen transfer reaction and the formation of dimerized clusters are earlier than the denitration *** the progress of the reaction,one side of the bitter amino group is removed from the pyridine ring,and then the pyridine ring is *** final products produced in the thermal decomposition process are CO_(2),H_(2)O,N_(2),and H_(2).Among them,H_(2)O has the earliest generation time,and the reaction rate constant(k_(3))is the *** clusters are formed during the decomposition of PYX,and the formation,aggregation,and decomposition of these clusters are strongly affected by *** low temperatures(2500 K-2750 K),many clusters are *** high temperatures(2750 K-3250 K),the clusters aggregate to form larger *** 3500 K,the large clusters decompose and become *** the late stage of the reaction,H and N in the clusters escaped almost entirely,but more O was trapped in the clusters,which affected the auto-oxidation process of ***'s initial decomposition activation energy(E_(a))was calculated to be 126.58 kJ/*** work contributes to a theoretical understanding of PYX's entire thermal decomposition process.

关键词： PYX Thermal decomposition ReaxFF-lg MD simulations Excellent thermostable explosives

Effects of Atmospheric Pressure on Developmental Characteristics and the Stability of Air Entraining Agent for Concrete

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Journal of Wuhan University of Technology(Materials Science) 2024年第4期39卷 979-989页

作者：李立辉牛开民 TIAN Bo chen Xin fu Ziqian ZHU Xuwei School of Civil Engineering Chongqing Jiaotong UniversityChongqing 400074China Transportation Science and Engineering Harbin Institute of TechnologyHarbin 150090China Research Institute of Highway Ministry of TransportBeijing 100088China

In order to ascertain the effects of atmospheric pressure on developmental characteristics and the stability of AEA(air-entraining agent)solution bubbles,AEA solution experiments and AEA solution bubble experiments were,respectively,conducted in Peking(50 m,101.2 kPa)and Lhasa(3,650 m,63.1 kPa).Surface tensions and inflection-point concentrations were tested based on AEA solutions,whilst developmental characteristics,thicknesses and elastic coefficients of liquid films were tested based on air bubbles of AEA *** study involved three types of AEAs,which were TM-O,226A,and *** experimental results show that initial sizes of TM-O,226A,and 226S are,respectively,increased by 43.5%,17.5%,and 3.8%.With the decrease of ambient pressure,the drainage rate and the drainage index of AEA solution bubbles *** experiments show that the liquid film thicknesses of all tested AEA solution bubbles are in micron *** the atmospheric pressure decreases from 101.2 to 63.1 kPa,the liquid film thicknesses of three types of AEA solutions decrease in various degrees;and film elasticities at critical thicknesses *** film of 226S solution bubbles is the most stable,presenting as a minimum thickness *** should be noted that elastic coefficient of liquid film only represents the level at critical thickness,thus it can not be applied as the only evaluating indicator of bubble *** a type of AEA,factors affecting the stability of its bubbles under low atmospheric pressure include initial bubbles size,liquid film thickness,liquid film elasticity,ambient temperature,etc.

关键词： air-entraining agent surface tension bubble size liquid film thickness liquid film elasticity atmospheric pressure

Towards Sustainable Grinding of Difficult-to-Cut Alloys-A Holistic Review and Trends

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 1-28页

作者： Ning Qian Jiajia chen Aqib Mashood Khan Biao Zhao Yurong chen Wenfeng Ding Yucan fu Jiuhua Xu Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Mechanical and Electronic Engineering Nanjing Forestry UniversityNanjing 210037China JITRI Institute of Precision Manufacturing Nanjing 211805China

Grinding,a critical precision machining process for difficult-to-cut alloys,has undergone continual technological advancements to improve machining ***,the sustainability of this process is gaining heightened attention due to significant challenges associated with the substantial specific grinding energy and the extensive heat generated when working with difficult-to-cut alloys,renowned for their exceptional physical and mechanical *** response to these challenges,the widespread application of massive coolant in manufacturing industries to dissipate grinding heat has led to complex post-cleaning and disposal ***,in turn,has resulted in issues such as large energy consumption,a considerable carbon footprint,and concerns related to worker health and safety,which have become the main factors that restrict the development of grinding *** paper provides a holistic review of sustainability in grinding difficult-to-cut alloys,encompassing current trends and future *** examination extends to developing grinding technologies explicitly tailored for these alloys,comprehensively evaluating their sustainability ***,the exploration delves into innovative sustainable technologies,such as heat pipe/oscillating heat pipe grinding wheels,minimum quantity lubrication,cryogenic cooling,and *** groundbreaking technologies aim to reduce dependence on hazardous coolants,minimizing energy and resource consumption and carbon emissions associated with coolant-related or subsequent disposal *** essence of these technologies lies in their potential to revolutionize traditional grinding practices,presenting environmentally friendly ***,future development trends and research directions are put forward to pursue the current limitation of sustainable grinding for difficult-to-cut *** paper can guide future research and development efforts toward more environmentally friendly

关键词： Grinding Sustainability Cooling Energy consumption Carbon footprint Difficult-to-cut alloys

Quantitative prediction model for the depth limit of oil accumulation in the deep carbonate rocks:A case study of Lower Ordovician in Tazhong area of Tarim Basin

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Petroleum Science 2024年第1期21卷 115-124页

作者： Wen-Yang Wang Xiong-Qi Pang Ya-Ping Wang Zhang-Xin chen fu-Jie Jiang Ying chen State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum(Beijing)Beijing102249China College of Geosciences China University of Petroleum(Beijing)Beijing102249China Research Institute of Exploration and Development PetroChina Southwest Oil&Gas Field CompanyChengdu610041SichuanChina Chemical and Petroleum Engineering Schulich School of EngineeringUniversity of CalgaryCalgaryT2N 1N4Canada

With continuous hydrocarbon exploration extending to deeper basins,the deepest industrial oil accumulation was discovered below 8,200 m,revealing a new exploration ***,the extent to which oil exploration can be extended,and the prediction of the depth limit of oil accumulation(DLOA),are issues that have attracted significant attention in petroleum *** it is difficult to characterize the evolution of the physical properties of the marine carbonate reservoir with burial depth,and the deepest drilling still cannot reach the ***,the DLOA cannot be predicted by directly establishing the relationship between the ratio of drilling to the dry layer and the *** this study,by establishing the relationships between the porosity and the depth and dry layer ratio of the carbonate reservoir,the relationships between the depth and dry layer ratio were obtained *** depth corresponding to a dry layer ratio of 100%is the *** on this,a quantitative prediction model for the DLOA was finally *** results indicate that the porosity of the carbonate reservoir,Lower Ordovician in Tazhong area of Tarim Basin,tends to decrease with burial depth,and manifests as an overall low porosity reservoir in deep *** critical porosity of the DLOA was 1.8%,which is the critical geological condition corresponding to a 100%dry layer ratio encountered in the *** depth of the DLOA was 9,000 *** study provides a new method for DLOA prediction that is beneficial for a deeper understanding of oil accumulation,and is of great importance for scientific guidance on deep oil drilling.

关键词： Deep layer Tarim Basin Hydrocarbon accumulation Depth limit of oil accumulation Prediction model

Novel Hf_(x)Ta_(1−x)C solid solution nanowire toughened HfC coating:An effective strategy for synchronous enhanced mechanical and anti-ablation performance

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Journal of Advanced Ceramics 2024年第5期13卷 590-601页

作者： Hui chen Yulei Zhang Yanqin fu Wenhan Gai Junhao Zhao Haohui Zhang Shaanxi Key Laboratory of Fiber Reinforced Light Composite Materials Northwestern Polytechnical UniversityXi’an 710072China Henan Key Laboratory of High Performance Carbon Fiber Reinforced Composites Institute of Carbon Matrix CompositesHenan Academy of SciencesZhengzhou 450046China

Ultra-high-temperature ceramic nanowires have shown increasing potential for use as thermal structural ***,novel single-crystal Hf_(0.5)Ta_(0.5)C solid solution nanowires were synthesized and incorporated with a HfC coating to construct a robust structure with Hf_(0.5)Ta_(0.5)C solid solution nanowires uniformly distributed and interconnected within the *** novel Hf_(0.5)Ta_(0.5)C solid solution nanowires could effectively hinder crack propagation through crack tip pinning and crack *** mechanism substantially enhanced the elastic modulus and fracture toughness of the HfC coating by 53.29%and 59.67%,*** toughened HfC coating displayed superior fracture toughness and good interfacial binding strength with the substrate to resist severe oxidation and ***,the high thermal conductivity of the toughened HfC coating promoted heat ***,in comparison to the pure HfC coating,the toughened HfC coating displayed smaller mass and linear ablation rates of−0.35 mg·s^(−1)and−0.46μm·s^(−1),which decreased by 39.66%and 36.98%,*** work not only simultaneously enhances the mechanical properties and ablation resistance of HfC-coated carbon/carbon(C/C)composites but also provides novel prospects for advanced ultrahigh-temperature ceramic nanowires under extreme conditions.

关键词： Hf_(x)Ta_(1−x)C solid solution nanowires HfC coating carbon/carbon(C/C)composites mechanical performance ablationresistance

Modelling and mechanical characteristics of PDC cutter-rock interaction by combining mixed fragmentation modes with dynamic rock strength

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Petroleum 2024年第3期10卷 474-482页

作者： Guangjian Dong Ping chen Xudong Wang Jianhong fu Yingxin Yang State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500China School of Petroleum Engineering Southwest Petroleum UniversityChengdu610500China Periodical Office of Southwest Petroleum University Southwest Petroleum UniversityChengdu610500China School of Mechatronic Engineering Southwest Petroleum UniversityChengdu610500China

Polycrystalline diamond compact(PDC)bit is one of the most widely used drill bits for improving the rate of penetration in deep oil and gas well and geothermal ***,the dynamic rock fragmentation mechanics characteristics of PDC bits are still unclearly.A coupled fragmentation mechanics model of PDC cutter-rock interaction is established by combining the mixed fragmentation modes with dynamic *** coupling influence laws of cutter angle,cutting depth,dynamic strength ratio,breaking modes on the horizontal force coefficient(HFC),vertical force coefficient(VFC)and specific energy are *** model of this paper can optimize cutter inclination angle,cutting depth and minimum specific *** the increase of the cutter inclination angle,the dynamic VFC changes into two *** definition of the dynamic modes depends on the dynamic strength *** the cutting angle increases,the cutting force *** cutting force increases nonlinearly with increasing cutting *** specific energy of rock fragmentation increases nonlinearly with increasing cutting *** the increase of dynamic strength,the specific energy of rock fragmentation increases *** the input-energy increases,the rate of penetration response is divided into three *** results have important guiding significance for the PDC bit design and drilling parameters optimization to increase the rate of penetration and the efficiency of exploration and development.

关键词： Mechanical characteristics PDC cutter-rock inter action Mixed fragmentation modes Dynamic rock strength

Enhancing the electrochemical performance of Na metal anodes via local eutectic melting in porous Al-Cu alloy hosts

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Nano Research 2024年第7期17卷 6111-6118页

作者： Tao Hu Qiang Wu cheng Wang Jialu chen fu Su Zibo chen Yizhou Wang Jianyu chen Yanwen Ma Jin Zhao State Key Laboratory of Organic Electronics and Information Displays&Institute of Advanced Materials(IAM) Nanjing University of Posts&Telecommunications9 Wenyuan RoadNanjing 210023China Materials Science and Engineering King Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Saudi Arabia Suzhou Vocational Institute of Industrial Technology 1 Zhineng AvenueSuzhou International Education ParkSuzhou 215104China

Sodium(Na)metal batteries(SMBs)have emerged as promising alternatives to lithium metal batteries for large-scale energy storage applications,owing to their cost-effectiveness,abundance,and favorable redox ***,the practical implementation of SMBs faces several challenges associated with the Na metal anode,including the formation of dendrites,low Coulombic efficiency,and capacity ***,we propose a novel approach to enhance the electrochemical performance of Na metal anodes through a porous Al-Cu alloy host(PAC)fabricated by a local eutectic melting *** local eutectic melting facilitates the development of a conductive network,offering mechanical support,and the porous structure provides abundant channels for the diffusion of Na ions and accommodates volume fluctuations in the Na metal during charge–discharge ***,the PAC exhibits a high average Coulombic efficiency of 99.8%at 1 mA·cm^(−2)for 1 mAh·cm^(−2)and a low voltage polarization of 19 mV during 500 *** study provides valuable insight into the design and fabrication of highperformance Na metal anodes,which hold significant promise for the advancements of next-generation energy storage systems.

关键词： Na metal anode porous Al-Cu alloy porous current collector local eutectic melting

Modelling smear effect of vertical drains using a diameter reduction method

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 279-290页

作者： Zhichao Shen Siau chen Chian Siew Ann Tan chun Fai Leung School of Marine Science and Engineering South China University of TechnologyGuangzhouChina Department of Civil and Environmental Engineering National University of SingaporeSingapore

Vertical drains are used to accelerate consolidation of clays in ground improvement *** zones exist around these drains,where permeability is reduced due to soil disturbance caused by the installation *** solution is widely used in practice to consider the effects of drain discharge capacity and smear on the consolidation *** this study,a computationally efficient diameter reduction method(DRM)obtained from the Hansbo solution is proposed to consider the smear effect without the need to model the smear zone *** by analytical and numerical results,a diameter reduction factor is analytically derived to reduce the diameter of the drain,while achieving similar solutions of pore pressure dissipation profile as the classical full model of the smear zone and *** the DRM,the excess pore pressure u obtained from the reduced drain in the original un-disturbed soil zone is accurate enough for practical applications in numerical *** performance of DRM is independent of soil material *** also show equally accurate performance of DRM under conditions of multi-layered soils and coupled radial-vertical groundwater flow.

关键词： Consolidation Vertical drain Smear effect Pore pressure Soil improvement

Facile identification of fluorosurfactant category in aqueous film-forming foam concentrates via optimized^(19)F NMR

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Magnetic Resonance Letters 2024年第3期4卷 42-51页

作者： Peiyao chen Shuang Zhuang Weiguang chen Zhijian chen Rongzhen Li Fangyu chen Tingting Jiang Xiaobin fu Tianjin Fire Research Institute of MEM Tianjin300381China Department of Chemistry School of ScienceTianjin UniversityTianjin300354China Department of Chemistry School of ScienceTianjin Chengjian UniversityTianjin300384China Department of Molten Salt Chemistry and Engineering Shanghai Institute of Applied PhysicsChinese Academy of SciencesShanghai201800China

Aqueous film-forming foams(AFFFs)are the primary source of toxic perfluoroalkyl and polyfluoroalkyl substances(PFAS)in ***,it is urgent to develop a facile and fast method for identifying fluorosurfactants in commercially available *** this work,fluorine nuclear magnetic resonance(^(19)F NMR)spectroscopy was optimized to measure AFFFs directly with the extra addition of 5%D_(2)O as the locking reagent,and high-quality spectra could be acquired within 4 min(0.1%fluorosurfactant content).Recovery experiments demonstrated that the use of different AFFFs had no marked influence on the quantitative analysis of *** method works with low-field NMR spectroscopy(1.4 T)as ***-dimensional(2D)^(19)F COSY NMR was used to make signal assignments for different fluorosurfactant *** optimized ^(19)F NMR could quantify the commercially available fluorosurfactants in different AFFFs,identify them being in either the perfluorooctane sulfonate(PFOS)or fluorotelomer sulfonic acid(FTS)categories,and distinguish the head-group of PFOS and FTS derivatives,which exhibits great potentials in the developments of relevant commercial detections.

关键词： Aqueous film-forming foams Fluorosurfactants 19F NMR Perfluorooctane sulfonate