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Thermal Behavior,Nonisothermal Decomposition Reaction Kinetics of Mixed Ester Double-base Gun Propellants

Chemical Research in Chinese Universities 2008年第5期24卷 608-614页

作者： YI Jian-hua ZHAO feng-qi xu Si-yu GAO Hong-xu HU Rong-zu Xi＇an Modern Chemistry Research Institute Xi＇an 710065 P. R. China

The thermal decomposition behavior and nonisothermal reaction kinetics of the double-base gun propellants containing the mixed ester of triethyleneglycol dinitrate（TEGDN） and nitroglycerin（NG） were investigated by thermogravimetry（TG） and differential thermogravimetry（DTG）, and differential scanning calorimetry（DSC） under the high-pressure dynamic ambience. The results show that the thermal decomposition processes of the mixed nitric ester gun propellants have two mass-loss stages. Nitric ester evaporates and decomposes in the first stage, and nitrocellulose and centralite II（C2） decompose in the second stage. The mass loss, the DTG peak points, and the terminated temperatures of the two stages are changeable with the difference of the mass ratio of TEGDN to NG. There is only one obvious exothermic peak in the DSC curves under the different pressures. With the increase in the furnace pressure, the peak temperature decreases, and the decomposition heat increases. With the increase in the content of TEGDN, the decomposition heat decreases at 0.1 MPa and rises at high pressure. The variety of mass ratio of TEGDN to NG makes few effect on the exothermic peak temperatures in the DSC curves at different pressures. The kinetic equation of the main exothermal decomposition reaction of the gun propellant TG0601 was determined as： dα/dt=1021.59（1-α）3e-2.60×104/T. The reaction mechanism of the process can be classified as chemical reaction. The critical temperatures of the thermal explosion（Tbe and Tbp） obtained from the onset temperature（Te） and the peak temperature（Tp） are 456.46 and 473.40 K, respectively. ΔS≠, ΔH≠, and ΔG≠ of the decomposition reaction are 163.57 J·mol^-1·K^-1, 209.54 kJ·mol^-1, and 133.55 kJ·mol^-1, respectively.

关键词： Mixed nitric ester gun propellant Triethyleneglycol dinitrate Thermal behaviors Nonisothermal decomposition reaction kinetics

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Block dual Toeplitz Operators on the Orthogonal Complements of Fock Spaces

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Acta Mathematica Sinica,English Series 2024年第8期40卷 1967-1988页

作者： Jian Xiang DONG Chun xu xu yu feng LU School of Mathematical Sciences Dalian University of TechnologyDalian 116024P.R.China School of Mathematics and Information Science Guangzhou UniversityGuangzhou 510006P.R.China

In this paper,we characterize the boundedness and compactness of the block dual Toeplitz operators acting on the orthogonal complement of the Fock spaces,and the compactness of the finite sum of two dual Toeplitz oper... 详细信息

关键词： Block dual Toeplitz operators boundedness compactness Fock space (semi)-commutator

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Effect of fertigation frequency on soil nitrogen distribution and tomato yield under alternate partial root-zone drip irrigation

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Journal of Integrative Agriculture 2023年第3期22卷 897-907页

作者： feng xu-yu PU Jing-xuan LIU Hai-jun WANG Dan LIU yu-hang QIAO Shu-ting LEI Tao LIU Rong-hao College of Water Resources Science and Engineering Taiyuan University of TechnologyTaiyuan 030024P.R.China College of Water Sciences Beijing Normal UniversityBeijing 100875P.R.China Beijing Key Laboratory of Urban Hydrological Cycle and Sponge City Technology Beijing Normal UniversityBeijing 100875P.R.China Shanxi Province Key Laboratory of Soil Environment and Nutrient Resources Taiyuan 030031P.R.China

Alternate partial root-zone drip fertigation (ADF) is a combination of alternating irrigation and drip fertigation,with the potential to save water and increase nitrogen (N) fertilizer efficiency.A 2-year greenhouse experiment was conducted to evaluate the effect of different fertigation frequencies on the distribution of soil moisture and nutrients and tomato yield under *** treatments included three ADF frequencies with intervals of 3 days (F3),6 days (F6) and 12 days (F12),and conventional drip fertigation as a control (CK),which was fertilized once every 6 *** the ADF treatments,two drip tapes were placed 10 cm away on each side of the tomato row,and alternate drip irrigation was realized using a manual valve on the distribution *** the CK treatment,a drip tape was located close to the roots of the tomato *** total N application rate of all treatments was 180 kg ha^(-1).The total irrigation amounts applied to the CK treatment were450.6 and 446.1 mm in 2019 and 2020,respectively;and the irrigation amounts applied to the ADF treatments were 60%of those of the CK *** F3 treatment resulted in water and N being distributed mainly in the 0–40-cm soil layer with less water and N being distributed in the 40–60-cm soil *** F6 treatment led to 21.0 and 29.0%higher 2-year average concentration of mineral N in the 0–20 and 20–40-cm soil layer,respectively and a 23.0%lower N concentration in the 40–60-cm soil layer than in the CK *** 2-year average tomato yields of the F3,F6,F12,and CK treatments were 107.5,102.6,87.2,and 98.7 t ha^(-1),*** tomato yield of F3 was significantly higher (23.3%) than that in the F12 treatment,whereas there was no significant difference between the F3 and F6 *** F6 treatment resulted in yield similar to the CK treatment,indicating that ADF could maintain tomato yield with a 40%saving in water *** on the distribution of water and N,and tomato yield,a fertigation frequency

关键词： alternate partial root-zone irrigation drip fertigation soil water soil mineral content tomato yield

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Spatial diversion and coordination of flood water for an urban flood control project in Suzhou, China

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Water Science and Engineering 2024年第2期17卷 108-117页

作者： yu xu You-peng xu Qiang Wang yue-feng Wang Chao Gao Department of Geography and Spatial Information Techniques Ningbo UniversityNingbo 315211China State Key Laboratoryof Hydology Water Resources and Hydraulic Enginering Nanjing Hydraulic Research InstitueNanjing 210029China Laboratory of Sustainable Urban Drainage Ningbo UniversityNingbo 31521lChina Schol of Gegraphical and Oceanographic Sciences Nanjing UniversiyNanjing 210023China School of Geography and Tourism Chongqing Normal UniversityChongqing 401331China

Suzhou City,located in the Yangtze River Delta in China,is prone to flooding due to a complex combination of natural factors,including its monsoon climate,low elevation,and tidally influenced position,as well as intensive human *** Large Encirclement Flood Control Project(LEFCP)was launched to cope with serious floods in the urban *** project changed the spatiotemporal pattern of flood processes and caused spatial diversion of floods from the urban area to the outskirts of the ***,this study developed a distributed flood simulation model in order to understand this transition of flood *** results revealed that the LEFCP effectively protected the urban areas from floods,but the present scheduling schemes resulted in the spatial diversion of floods to the outskirts of the *** rainstorm frequencies of 10.0%to 0.5%,the water level differences between two representative water level stations(Miduqiao(MDQ)and fengqiao(FQ))located inside and outside the LEFCP area,ranged from 0.75 m to 0.24 m and from 1.80 m to 1.58 m,*** addition,the flood safety margin at MDQ and the duration with the water level exceeding the warning water level at FQ ranged from 0.95 m to 0.43 m and from 4 h to 22 h,*** scheduling schemes for the hydraulic facilities of the LEFCP in extreme precipitation cases were developed ac-cording to food simulations under seven scheduling *** helps to regulate the spatial flood diversion caused by the LEFCP during extreme precipitation.

关键词： Urban flooding Urban flood control project Rainstorm fregue ncy Flood simulation model Suzhou City

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Reducing Subspaces of Toeplitz Operators Induced by a Class of Non-analytic Monomials over the Unit Ball

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Acta Mathematica Sinica,English Series 2024年第7期40卷 1767-1777页

作者： Yan yue SHI Bo ZHANG xu TANG yu feng LU School of Mathematical Sciences Ocean University of ChinaQingdao 266100P.R.China School of Mathematics and Information Sciences Yantai UniversityYantai 264005P.R.China School of Mathematical Sciences Space Engineering UniversityBeijing 101416P.R.China School of Mathematical Sciences Dalian University of TechnologyDalian 116024P.R.China

In this paper,we describe the minimal reducing subspaces of Toeplitz operators induced by non-analytic monomials on the weighted Bergman spaces and Dirichlet spaces over the unit ball B_(2).It is proved that each minimal reducing subspace M is finite dimensional,and if dim M≥3,then M is induced by a ***,the structure of commutant algebra v(T_(w)N_(z)N):={M^(*)_(w)NM_(z)N,M^(*)_(z)NM_(w)N}′is determined by N and the two dimensional minimal reducing subspaces of(T_(w)N_(z)*** also give some interesting examples.

关键词： Reducing subspace operator-weighted shifts Toeplitz operator von Neumann algebra

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Enhanced High-Temperature Energy Storage Performance of All-Organic Composite Dielectric via Constructing Fiber-Re in forced Structure

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Energy & Environmental Materials 2024年第2期7卷 299-307页

作者： Mengjia feng yu feng Changhai Zhang Tiandong Zhang xu Tong Qiang Gao Qingguo Chen Qingguo Chi Key Laboratory of Engineering Dielectrics and Its Application Ministry of EducationHarbin University of Science and TechnologyHarbin 150080China School of Electrical and Electronic Engineering Harbin University of Science and TechnologyHarbin 150080China

Optimizing the high-temperature energy storage characteristics of energy storage dielectrics is of great significance for the development of pulsed power devices and power control *** a polymer with a higher glass transition temperature(T_(g))as the matrix is one of the effective ways to increase the upper limit of the polymer operating ***,current high-T_(g)polymers have limitations,and it is difficult to meet the demand for high-temperature energy storage dielectrics with only one *** example,polyetherimide has high-energy storage efficiency,but low breakdown strength at high *** has high corona resistance,but low high-temperature energy storage *** this work,combining the advantages of two polymer,a novel high-T_(g)polymer fiber-reinforced microstructure is *** is designed as extremely fine fibers distributed in the composite dielectric,which will facilitate the reduction of high-temperature conductivity loss for *** the same time,due to the high-temperature resistance and corona resistance of polyimide,the high-temperature breakdown strength of the composite dielectric is *** the polyimide content with the best high-temperature energy storage characteristics is determined,molecular semiconductors(ITIC)are blended into the polyimide fibers to further improve the high-temperature ***,excellent high-temperature energy storage properties are *** 0.25 vol%ITIC-polyimide/polyetherimide composite exhibits high-energy density and high discharge efficiency at 150℃(2.9 J cm^(-3),90%)and 180℃(2.16 J cm^(-3),90%).This work provides a scalable design idea for high-performance all-organic high-temperature energy storage dielectrics.

关键词： all-organic energy storage density high-temperature high-temperature breakdown strength

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A real-time intelligent lithology identification method based on a dynamic felling strategy weighted random forest algorithm

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Petroleum Science 2024年第2期21卷 1135-1148页

作者： Tie Yan Rui xu Shi-Hui Sun Zhao-Kai Hou Jin-yu feng School of Petroleum Engineering Northeast Petroleum UniversityDaqing163318HeilongjiangChina Sanya Offshore Oil&Gas Research Institute Northeast Petroleum UniversitySanya572025HainanChina

Real-time intelligent lithology identification while drilling is vital to realizing downhole closed-loop drilling. The complex and changeable geological environment in the drilling makes lithology identification face many challenges. This paper studies the problems of difficult feature information extraction,low precision of thin-layer identification and limited applicability of the model in intelligent lithologic identification. The author tries to improve the comprehensive performance of the lithology identification model from three aspects: data feature extraction, class balance, and model design. A new real-time intelligent lithology identification model of dynamic felling strategy weighted random forest algorithm(DFW-RF) is proposed. According to the feature selection results, gamma ray and 2 MHz phase resistivity are the logging while drilling(LWD) parameters that significantly influence lithology identification. The comprehensive performance of the DFW-RF lithology identification model has been verified in the application of 3 wells in different areas. By comparing the prediction results of five typical lithology identification algorithms, the DFW-RF model has a higher lithology identification accuracy rate and F1 score. This model improves the identification accuracy of thin-layer lithology and is effective and feasible in different geological environments. The DFW-RF model plays a truly efficient role in the realtime intelligent identification of lithologic information in closed-loop drilling and has greater applicability, which is worthy of being widely used in logging interpretation.

关键词： Intelligent drilling Closed-loop drilling Lithology identification Random forest algorithm Feature extraction

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Water modeling on fluid flow and mixing phenomena in a BOF steelmaking converter

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Journal of Iron and Steel Research International 2024年第3期31卷 595-607页

作者： Xin-yu Cai Hao-jian Duan Ding-han Li Anjun xu Li-feng Zhang School of Metallurgical and Ecological Engineering University of Science and Technology Beijing(USTB)Beijing 100083China School of Mechanical and Materials Engineering North China University of TechnologyBeijing 100144China

A 1∶8 physical water model was constructed to investigate the fluid flow and mixing phenomena in the basic oxygen furnace(BOF)*** particle image velocimetry was employed to measure the velocity distribution of the bath and the high-speed camera was applied to capture the cavity shape in the combined blowing BOF *** mixing time for varied operating conditions was measured by the stimulus-response *** cavity depth increased with the decrease in the lance height and the increase in the top gas flow rate while the bottom blowing gas had little influence on the cavity *** minimum cavity depth was obtained under the condition of a 69.8 m^(3)/h top gas flow rate,a 287.5 mm lance height and a 0.93 m^(3)/h bottom blowing gas flow rate,which was 161.2 *** mixing time decreased as the lance height decreased and the top blowing gas flow rate *** mixing time was first decreased and then increased with the increase in the bottom gas flow *** the condition of 69.8 m^(3)/h gas flow rate of top blowing,the 287.5 mm lance height and the 0.93 m^(3)/h gas flow rate of bottom blowing,the mixing time in the converter was 48.65 *** empirical formula between the stirring power and the mixing time in the converter was calculated.

关键词： Water model Fluid flow Particle image velocimetry Mixing time BOF converter

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TRIM21-dependent ultrasmall chiral gold nanoparticles for preventing microglia senescence against Alzheimer's disease

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Science China Chemistry 2024年第4期67卷 1360-1372页

作者： Meiru Lu Changlong Hao Liguang xu feng yu Jiwei Jiang Yanli Wang Jun xu Hua Kuang Chuanlai xu Maozhong Sun International Joint Research Laboratory for Biointerface and Biodetection State Key Laboratory of Food Science and ResourcesSchool of Food Science and TechnologyJiangnan UniversityWuxi 214122China Institute of Life Sciences Jiangsu UniversityZhenjiang 212013China Department of Neurology Beijing Tiantan HospitalCapital Medical UniversityBeijing 100050China National Clinical Research Center for Neurological Diseases Beijing 100070China

Tripartite motif 21(TRIM21)is an E3 ubiquitin ligase that shows great promise for protein degradation through ***,ultrasmall chiral gold nanoparticles(D-or L-NPs)modified by D-or L-glutathione ligands were *** conjugated with an NLR family pyrin domain-containing protein 3(NLRP3)antibody(D-NP-a NLRP3 or L-NP-a NLRP3),DNP-a NLRP3 showed effective delivery efficiency of the antibody into microglia and prevented Aβ-mediated microglia senescence,and p16^(ink4a),a marker of senescence,in the microglia was reduced by 90.3%±7.8% while L-NP-a NLRP3 decreased by 48.01%±3.1%.Mechanistic investigations revealed that the D-NP-a NLRP3((1.5±0.3)×10^(7)M^(-1))exhibited sixteen-fold larger binding affinity to transmembrane glycoprotein SLC3A2 than L-type((9.5±2.7)×10^(5)M^(-1)),which led to a high efficiency of antibody delivery and TRIM21-dependent NLRP3 ***,the blood-brain barrier(BBB)-crossing ability of chiral NP-a NLRP3 as well as NLRP3 degradation was demonstrated in *** APP/PS1 Alzheimer's disease(AD)model mice experiments exhibited a reduction of 89.7%±6.8% for the NLRP3 protein and 84.2±7.5% for p16^(ink4a)following the intravenous administration of D-NP-a NLRP3 once a week for 60 ***,the levels of the AD markers Aβ and phosphorylatedTau in the brains were reduced by 86.2%±8.2% and 81.6%±9.1%;these were 2.1-fold and 1.9-fold higher than those treated with L-NP-a NLRP3,*** studies provide a method to rescue AD-like pathologies and prevent senescence.

关键词： chiral gold nanoparticles amyloid-β NLRP3 TRIM21 senescence Alzheimer's disease

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Prediction of three-dimensional ocean temperature in the South China Sea based on time series gridded data and a dynamic spatiotemporal graph neural network

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Acta Oceanologica Sinica 2024年第7期43卷 26-39页

作者： feng Nan Zhuolin Li Jie yu Suixiang Shi Xinrong Wu Lingyu xu Department of Computer Engineering and Science Shanghai UniversityShanghai 200444China Key Laboratory of Digital Ocean National Marine Data and Information ServiceTianjin 300171China

Ocean temperature is an important physical variable in marine ecosystems,and ocean temperature prediction is an important research objective in ocean-related ***,one of the commonly used methods for ocean temperature prediction is based on data-driven,but research on this method is mostly limited to the sea surface,with few studies on the prediction of internal ocean *** graph neural network-based methods usually use predefined graphs or learned static graphs,which cannot capture the dynamic associations among *** this study,we propose a novel dynamic spatiotemporal graph neural network(DSTGN)to predict threedimensional ocean temperature(3D-OT),which combines static graph learning and dynamic graph learning to automatically mine two unknown dependencies between sequences based on the original 3D-OT data without prior *** and spatial dependencies in the time series were then captured using temporal and graph *** also integrated dynamic graph learning,static graph learning,graph convolution,and temporal convolution into an end-to-end framework for 3D-OT prediction using time-series grid *** this study,we conducted prediction experiments using high-resolution 3D-OT from the Copernicus global ocean physical reanalysis,with data covering the vertical variation of temperature from the sea surface to 1000 m below the sea *** compared five mainstream models that are commonly used for ocean temperature prediction,and the results showed that the method achieved the best prediction results at all prediction scales.

关键词： dynamic associations three-dimensional ocean temperature prediction graph neural network time series gridded data

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