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Development of high-energy-density materials

Science China(Technological Sciences) 2020年第2期63卷 195-213页

作者： liu JiPing liu LiLi liu xiaobo School of Materials Science&Engineering Beijing Institute of TechnologyBeijing 100081China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

The performance of an energetic compound is mainly decided by parameters such as density, oxygen balance, heat of formation,and stability. Among these properties, density is the most important factor because it determines the detonation pressure and velocity. One of the trends in the development of high-energy-density materials(HEDMs) involves the study of energetic materials with high nitrogen levels. A compound with high nitrogen content can obtain substantial energy from the heat of formation rather than from the intramolecular oxidation of carbon skeleton to release energy in the form of a nitro group or nitrate ester. In addition to excellent performance, the newly developed energetic materials should also possess high working power and insensitivity toward external influences for ensuring the safety of charge and service, high energy release rate, long service life,good compatibility, excellent biological performance, low toxicity, safe battlefield environment, and low moisture absorption,which meet the requirements of military and civilian use. This review summarizes the research progress on global ***, FOX-7, octanitrocubanane, TAM, TKX-50, and N5 were believed to show promise in achieving application goals. The prospective vision of HEDMs containing ions, total nitrogen, metal hydrogen, and nuclear energetic isomers, overcoming technical barriers, synthesis of all-nitrogen materials, theoretical studies on desorption/adsorption system, and challenging technical problems that need to be solved for the safety of synthetic nitrogen compounds were discussed to further elucidate the effect of this subject.

关键词： total nitrogen high-energy-density material energetic ion salt metal hydrogen nuclear energetic isomer

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Quantum Hyperbolic Invariants for Diffeomorphisms of Small Surfaces

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Acta Mathematica Sinica,English Series 2012年第4期28卷 759-770页

作者： xiaobo liu Academy of Mathematics and Systems Science Chinese Academy of Sciences

An earlier article [Bonahon, F., liu, X. B.： Representations of the quantum Teichmfiller space and invariants of surface diffeomorphisms. Geom. Topol., 11, 889-937 （2007）] introduced new invariants for pseudo-Anosov diffeomorphisms of surface, based on the representation theory of the quantum Teichmiiller space. We explicitly compute these quantum hyperbolic invariants in the case of the 1-puncture torus and the 4-puncture sphere.

关键词： Quantum Teichmiiller space mapping torus representations

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Mechanism and characteristics of thermal action of HMX explosive mixture containing high-efficiency fuel

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Science China(Technological Sciences) 2019年第4期62卷 578-586页

作者： liu JiPing YANG WeiWei liu Ying liu xiaobo School of Materials Science & Engineering Beijing Institute of Technology State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology

In this study, the thermal stability and detonation properties of three types of explosives were investigated. Results indicated that nanoaluminum powder improved the detonation properties of HMX by increasing the specific surface area of HMX, which substantially increased the explosion heat and power. The decomposition temperatures of the three explosives containing aluminum hydride, ammonia borane, and nanoaluminum powder during slow cook-off at heating rates of 1.5 and 10°C min–1 were measured as 246°C and 241°C, 256°C and 261°C, and 238°C and 264°C, respectively. The explosives containing hydrogen storage materials swelled; however, the nanoaluminum powder was only slightly peeled off at the edge of the grains during cookoff. Differential scanning calorimetry(DSC) curves of the explosives containing hydrogen storage materials exhibited endothermic and exothermic peaks before the major exothermic reaction peak during the cook-off tests. In contrast, only one weak peak was observed in the DSC curve of the explosive containing nanoaluminum powder before the major exothermic reaction. In addition, the additives and adhesives catalyzed the slow cook-off decomposition, which caused the transformation of HMX crystals and accelerated the thermal decomposition reaction of HMX. The addition of high-density hydrogen storage materials to HMX resulted in detonation heats and explosion powers much greater than cure HMX. This improved performance was attributed to the hydrogen storage materials in the explosives participating in a secondary reaction in the reaction zone at the instant of the explosion, effectively realizing complementary lossless energy and thus greatly improving the explosive power of the explosives.

关键词： high-density hydrogen storage material nanoparticles thermal stability cook-off explosive performance detonation reaction

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Topological recursion relations on M_(3,2)

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Science China Mathematics 2015年第9期58卷 1909-1922页

作者： KIMURA Takashi liu xiaobo Department of Mathematics and Statistics Boston University Beijing International Center for Mathematical Research Peking University Department of Mathematics University of Notre Dame

We give some new genus-3 universal equations for Gromov-Witten invariants of compact symplectic manifolds. These equations were obtained by studying relations in the tautological ring of the moduli space of2-pointed genus-3 stable curves. A byproduct of our search for genus-3 equations is a new genus-2 universal equation for Gromov-Witten invariants.

关键词： Gromov-Witten invariants universal equations symplectic manifolds

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Aedes Surveillance and Risk Warnings for Dengue—China,2016−2019

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China CDC weekly 2020年第24期2卷 431-437页

作者： xiaobo liu Qiyong liu State Key Laboratory of Infectious Disease Prevention and Control Collaborative Innovation Center for Diagnosis and Treatment of Infectious DiseasesWHO Collaborating Centre for Vector Surveillance and ManagementNational Institute for Communicable Disease Control and PreventionChinese Center for Disease Control and PreventionBeijingChina

Introduction:Aedes surveillance plays an important role in the risk warning and control of dengue in *** study analyzed Aedes larval density and its indicated dengue risk in 23 provincial-level administrative divisions(PLADs)from 2016 to 2019 to provide scientific evidence for sustainable dengue management(SDM)in the ***:The Breteau index(BI)and Mosq-ovitrap index(MOI)methods were utilized for Aedes larvae surveillance in 23 PLADs with 3 categories based on dengue risk stratification and Aedes *** and MOI were calculated and then dengue risk warning was carried out for the guidance of SDM in these PLADs based on the findings of Aedes ***:The seasonal fluctuations of Aedes larval density were similar in six class I PLADs during 2016–2019,and the density of Aedes larvae was relatively high in the PLADs of Zhejiang,Hainan,and Fujian while it was relatively low in Yunnan and *** Shanghai and Jiangsu,the BI of all other class II PLADs had reached the dengue transmission threshold during the study *** class III PLADs,the BI had reached dengue transmission threshold in most months in Shandong and Hebei during the study *** MOI was higher than 5 from June to September in all the studied years in Guangdong and was higher in most studied years in *** MOI of Beijing in August reached dengue transmission or outbreak threshold from 2017 to *** and Implications for Public Health Practice:Most class I and class II PLADs were at risk of dengue transmission during the surveillance months,2016–*** Aedes surveillance and risk warnings should be carried out in specific PLADs so as to provide scientific basis for SDM in the future.

关键词： Aedes utilized surveillance

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Syn-tectonic sedimentation and its linkage to fold-thrusting in the region of Zhangjiakou, North Hebei, China

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Science China Earth Sciences 2018年第6期61卷 681-710页

作者： Shaofeng liu Chengfa LIN xiaobo liu Qitian ZHUANG School of Earth Sciences and Resources China University of Geosciences (Beijing) Institute of Geomechanics Chinese Academy of Geological Sciences

The timing of the "Yanshanian Movement" and the tectonic setting that controlled the Yanshan fold-and-thrust belt during Jurassic time in China are still matters of controversy. Sediments that filled the intramontane basins in the Yanshan belt perfectly record the history of "Yanshanian Movement" and the tectonic background of these basins. Recognizing syn-tectonic sedimentation, clarifying its relationship with structures, and accurately defining strata ages to build up a correct chronostratigraphic framework are the key points to further reveal the timing and kinematics of tectonic deformation in the Yanshan belt from the Jurassic to the Early Cretaceous. This paper applies both tectonic and sedimentary methods on the fold-and-thrust belt and intramontane basins in the Zhangjiakou area, which is located at the intersection between the western Yanshan and northern Taihangshan. Our work suggests that the pre-defined "Jurassic strata" should be re-dated and sub-divided into three strata units: a Late Triassic to Early Jurassic unit, a Middle Jurassic unit, and a Late Jurassic to early Early Cretaceous unit. Under the control of growth fold-and-thrust structures, five types of growth strata developed in different growth structures: fold-belt foredeep type,thrust-belt foredeep type, fault-propagation fold-thrust structure type, fault-bend fold-thrust structure type, and fault-bend foldthrust plus fault-propagation fold composite type. The reconstructed "source-to-sink" systems of Late Triassic to Early Jurassic,Middle Jurassic and Late Jurassic to early Early Cretaceous times, which are composed of a fold-and-thrust belt and flexure basins, imply that the "Yanshanian Movement" in our study area started in the Middle Jurassic. During Middle Jurassic to early Early Cretaceous times, there have been at least three stages of fold-thrust events that developed "Laramide-type" basementinvolved fold-thrust structures and small-scale intramontane broken "axial basins". The west

关键词： Yanshan-Taihangshan Fold-and-thrust belt Flexural basin Growth strata Source-to-sink system Thick-skinned fold-and-thrust belt

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Cascade conditional generative adversarial nets for spatial-spectral hyperspectral sample generation

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Science China(Information Sciences) 2020年第4期63卷 81-96页

作者： xiaobo liu Yulin QIAO Yonghua XIONG Zhihua CAI Peng liu School of Automation China University of Geosciences (Wuhan) Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems School of Computer Science China University of Geosciences (Wuhan) The Beibu Gulf Big Data Resources Utilization Laboratory Beibu Gulf University

Sample generation is an effective way to solve the problem of the insufficiency of training data for hyperspectral image classification. The generative adversarial network（GAN） is one of the popular deep learning methods, which utilizes adversarial training to generate the region of samples based on the required class label. In this paper, we propose cascade conditional generative adversarial nets for hyperspectral image complete spatial-spectral sample generation, named C;GAN. The C;GAN includes two stages. The stageone model consists of the spatial information generation with a window size that entails feeding random noise and the required class label. The second stage is the spatial-spectral information generation that generates spectral information of all bands in the spatial region by feeding the label regions. The visualization and verification of generated samples based on the Pavia University and Salinas datasets show superior performance, which demonstrates that our method is useful for hyperspectral image classification.

关键词： hyperspectral image sample generation generative adversarial nets(GAN) deep learning spatial-spectral information

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Dix-Type Multi-Component Scholte Wave Dispersion Inversion without Initial Model

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Journal of Earth Science 2024年第4期35卷 1393-1396页

作者： Linjing Zhao Xiangchun Wang xiaobo liu School of Geophysics and Information Technology China University of GeosciencesBeijing 100083China Key Laboratory of Intraplate Volcanoes and Earthquakes Ministry of EducationChina University of GeosciencesBeijing 100083China School of Ocean Sciences China University of GeosciencesBeijing 100083China Key Laboratory of Polar Geology and Marine Mineral Resources Ministry of EducationChina University of GeosciencesBeijing 100083China

0 INTRODUCTION Scholte wave dispersion curves contain rich information regarding seafloor media and have therefore attracted increasing attention(Wang et al.,2022;Dong et al.,2021;Du et al.,2020).Ocean bottom seismometer(OBS)data are widely used in the study of seafloor medium information(Wang et al.,2024),and contain rich surface wave information.

关键词： seafloor wave Inversion

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Factors influencing methane diffusion behaviors in micro-nano coal pores: a comprehensive study

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Frontiers of Earth Science 2023年第1期17卷 71-86页

作者： Xianglong FANG Dameng liu Yingfang ZHOU xiaobo liu Yidong CAI School of Energy Resources China University of GeosciencesBeijing 100083China Coal Reservoir Laboratory of National Engineering Research Center of CBM Development&Utilization China University of GeosciencesBeijing 100083China School of Engineering Fraser Noble BuildingKing's CollegeUniversity of AberdeenAB243UE AberdeenUK Postdoctoral Workstation of Applied Technology Research Institute Northeast Petroleum UniversityDaqing 163318China

Gas diffusion in the coal matrix plays a significant role in forecasting the production performance of coalbed methane(CBM)*** better understand methane diffusion behavior,a systematic study was performed on various rank coals with vitrinite reflectance(Ro,m)ranging from 0.46%to 2.79%.Multiple experiments,including coal petrographic analysis,field emission scanning electron microscopy(FESEM),low-temperature N2 adsorption/desorption,and mercury intrusion porosimetry(MIP),were conducted to quantitatively characterize the multiscale micro-nano pore system in different rank coals,which showed that the pore structure of coals exhibited a multimodal pore size and volume *** adsorption-diffusion experiments using the volumetric method were also performed to understand the methane diffusion characteristics in the micro-nano pores of the coal *** applicability of the multiporous diffusion model is verified,and methane diffusion in the multi-scale pores of coal reservoirs exhibits the characteristics of early fast diffusion,transitional diffusion in the medium term,and slow diffusion in the later *** addition,the factors affecting methane diffusion in coals were systematically analyzed,and gray relational analysis(GRA)was employed to analyze and identify the importance of these factors on methane *** results show the impact ranking of factors,in order from the most important to the least:particle size>moisture>surface area>pore volume>pressure>coal rank>temperature in all of three diffusion *** findings are helpful for forecasting production performance and enhancing the production efficiency of CBM.

关键词： coalbed methane reservoir micro-characteristic diffusion coefficient grey relational analysis

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Improved EEMD-based standardization method for developing long tree-ring chronologies

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Journal of Forestry Research 2020年第6期31卷 2217-2224页

作者： Xianliang Zhang Junxia Li xiaobo liu Zhenju Chen College of Forestry Hebei Agricultural UniversityBaoding 071001People’s Republic of China College of Forestry Shenyang Agricultural UniversityShenyang 110866People’s Republic of China Long-term Forest Silviculture Research Station in Saihanba Chengde 067000People’s Republic of China

Long tree-ring chronologies can be developed by overlapping data from living trees with data from fossil trees through ***,low-frequency climate signals are lost when standardizing tree-ring series due to the"segment length curse".To alleviate the segment length curse and thus improve the standardization method for developing long tree-ring chronologies,here we first calculated a mean value for all the tree ring series by overlapping all of the tree ring *** growth trend of the mean tree ring width(i.e.,cumulated average growth trend of all the series)was determined using ensemble empirical mode *** the chronology was developed by dividing the mean value by the growth trend of the mean *** improved method alleviated the problem of trend ***-term signals were better preserved using the improved method than in previous detrending *** chronologies developed using the improved method were better correlated with climate than those developed using conservative *** improved standardization method alleviates trend distortion and retains more of the low-frequency climate signals.

关键词： Standardization methods Tree rings Segment length curse Detrending

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