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Assessing the performance of molecular gas clump identification algorithms

Research in Astronomy and Astrophysics 2020年第3期20卷 62-75页

作者： Chong Li Hong-Chi Wang Yuan-Wei Wu Yue-Hui Ma liang-hao lin Purple Mountain Observatory and Key Laboratory of Radio Astronomy Chinese Academy of SciencesNanjing 210033China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Precise Positioning and Timing Technology National Time Service CenterChinese Academy of SciencesXi'an 710600China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China

The detection of clumps(cores)in molecular clouds is an important issue in sub-millimetre ***,the completeness of the identification and the accuracy of the returned parameters of the automated clump identification algorithms are still not *** this work,we test the performance and bias of the GaussClumps,ClumpFind,FellWalker,Reinhold,and Dendrograms algorithms in identifying simulated *** designing the simulated clumps with various sizes,peak brightness,and crowdedness,we investigate the characteristics of the algorithms and their *** the aspect of detection completeness,FellWalker,Dendrograms,and GaussClumps are the first,second,and third best algorithms,*** numbers of correct identifications of the six algorithms gradually increase as the size and signal-to-noise ratio(SNRs)of the simulated clumps increase and they decrease as the crowdedness *** the aspect of the accuracy of retrieved parameters,FellWalker and Dendrograms exhibit better performance than the other *** average deviations in clump parameters for all algorithms gradually increase as the size and SNR of clumps *** of the algorithms except FellWalker exhibit significant deviation in extracting the total flux of *** together,FellWalker,GaussClumps,and Dendrograms exhibit the best performance in detection completeness and extracting *** deviation in virial parameter for the six algorithms is relatively *** applying the six algorithms to the clump identification for the Rosette molecular cloud,ClumpFind1994,ClumpFind2006,GaussClumps,FellWalker,and Reinhold exhibit performance that is consistent with the results from the simulated test.

关键词： methods:data analysis methods:numerical ISM:structure

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A cold and diffuse giant molecular filament in the region of l=41°,b=-1°

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Research in Astronomy and Astrophysics 2020年第9期20卷 215-227页

作者： liang-hao lin Hong Chi Wang Yang Su Chong Li Ji Yang lPurple Mountain Observatory and Key Laboratory of Radio Astronomy Chinese Academy of SciencesNanjing 210033China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China University of Chinese Academy of Sciences Beijing 100049China

Data of 12CO/13CO/C180 J=1→0 emission toward the Galactic plane region of l=35°to 450 and b=-5°to+5°are available with the Milky Way Imaging Scroll Painting(MWISP)*** the data,we found a giant molecular filament(GMF)around l≈38°42°,b≈-3.5°0°,VLSR≈2740 km s-1,named the GMF MWISP *** a distance of 1.7 kpc,the GMF is about 160 pc *** a median excitation temperature about 7.5 K and a median column density about1021 cm-2,this GMF is very cold and very diffuse compared to known *** the morphology in the data cube,the GMF is divided into four components among which three show filamentary *** of the components are 103104 M☉,with a total mass for the whole filament being about 7×104 M☉from the local thermodynamic equilibrium method.13CO cores inside each component are *** parameters are about 2.5 for these cores and have a power-law index of-0.34 against the *** mass fraction of dense cores traced by 13CO to the diffuse clouds traced by 12CO is about 7%for all components of the *** found signatures of possible large scale filament-filament collision in the GMF.

关键词： ISM:molecules ISM:clouds ISM:individual(GMF MWISP G041–01) ISM:kinematics and dynamics

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Digital signal acquisition system for complex nuclear reaction experiments

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Nuclear Science and Techniques 2024年第1期35卷 124-133页

作者： Wei-liang Pu Yan-lin Ye Jian-ling Lou Jia-hao Chen School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking UniversityBeijing 100871China Institute of Applied Physics and Computational Mathematics Beijing 100094China

A digital data-acquisition system based on XIA LLC products was used in a complex nuclear reaction experiment using radioactive ion beams.A flexible trigger system based on a field-programmable gate array(FPGA)parametrization was developed to adapt to different experimental sizes.A user-friendly interface was implemented,which allows converting script language expressions into FPGA internal control *** proposed digital system can be combined with a conventional analog data acquisition system to provide more *** performance of the combined system was veri-fied using experimental data.

关键词： Digital signal acquisition system Trigger Programmable logic Timestamp

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A reduced combustion mechanism of ammonia/diesel optimized with multi-objective genetic algorithm

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Defence Technology（防务技术） 2024年第4期34卷 187-200页

作者： Wanchen Sun Shaodian lin hao Zhang liang Guo Wenpeng Zeng Genan Zhu Mengqi Jiang State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130025China

For the deep understanding on combustion of ammonia/diesel,this study develops a reduced mechanism of ammonia/diesel with 227 species and 937 *** sub-mechanism on ammonia/interactions of N-based and C-based species(N—C)/NOx is optimized using the Non-dominated Sorting Genetic Algorithm II(NSGA-II)with 200 *** optimized mechanism(named as 937b)is validated against combustion characteristics of ammonia/methane(which is used to examine the accuracy of N—C interactions)and ammonia/diesel *** ignition delay times(IDTs),the laminar flame speeds and most of key intermediate species during the combustion of ammonia/methane blends can be accurately simulated by 937b under a wide range of *** for ammonia/diesel blends with various diesel energy fractions,reasonable predictions on the IDTs under pressures from 1.0 MPa to5.0 MPa as well as the laminar flame speeds are also achieved by *** particular,with regard to the IDT simulations of ammonia/diesel blends,937b makes progress in both aspects of overall accuracy and computational efficiency,compared to a detailed ammonia/diesel *** kinetic analysis reveals that the reaction pathway of ammonia during the combustion of ammonia/diesel blend mainly differs in the tendencies of oxygen additions to NH_2 and NH with different equivalence ratios.

关键词： Ammonia Diesel Combustion Kinetic mechanism Multi-objective optimization

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Analysis and experimental study on resistance-increasing behavior of composite high efficiency autonomous inflow control device

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Petroleum Science 2024年第2期21卷 1290-1304页

作者： liang-liang Dong Yu-lin Zhang School of Mechatronic Engineering Southwest Petroleum UniversityChengdu610500SichuanChina State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500SichuanChina Oil and Gas Equipment Technology Sharing and Service Platform of Sichuan ProvinceChengdu610500SichuanChina

Bottom water coning is the main reason to reduce the recovery of horizontal bottom water reservoir. By water coning, we mean the oil-water interface changes from a horizontal state to a mound-shaped cone and breaks through to the wellbore. Autonomous inflow control device(AICD) is an important instrument maintain normal production after bottom water coning, however, the resistance increasing ability of the swirl type AICD is insufficient at present, which seriously affects the water control effect. Aiming this problem, this paper designs a multi-stage resistance-increasing and composite type AICD. The separation mechanism of oil-water two phases in this structure, the resistance form of oil-water single phase and the resistance-increasing principle of water phase are analyzed. Establishing the dual-phase multi-stage separation and resistance-increasing model, and verified by measuring the throttling pressure drop and oil-water volume fraction of the AICD, it is found that the composite type AICD has the effect of ICD and AICD at the same time, which can balance the production rate of each well section at the initial stage of production, delay the occurrence of bottom water coning. In the middle and later stages of production, water-blocking can be effectively increased to achieve water control and stable *** structural sensitivity analysis, the influence law of various structural parameters on the water control performance of composite AICD was obtained. The simulation calculation results show that,compared with the existing swirl type AICD, composite AICD has higher sensitivity to moisture content,the water phase throttling pressure drop is increased by 4.5 times on average. The composite AICD is suitable for the entire stage of horizontal well production.

关键词： Water control Flow separation Flow resistance-increasing AICD device Simulation and experiment

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A new interacting capillary bundle model on the multiphase flow in micropores of tight rocks

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Petroleum Science 2024年第2期21卷 1099-1112页

作者： Wen-Quan Deng Tian-Bo liang Wen-Zhong Wang hao Liu Jun-lin Wu Fu-Jian Zhou National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing102249China

Surfactants are widely used in the fracturing fluid to enhance the imbibition and thus the oil recovery rate. However, current numerical models cannot capture the physics behind capillary imbibition during the wettability alteration by surfactants. Although the interacting capillary bundle(ICB) model shows potential in characterizing imbibition rates in different pores during wettability alteration, the existing ICB models neglect the influence of wettability and viscosity ratio on the imbibition behavior, making it difficult to accurately describe the oil-water imbibition behavior within the porous media. In this work,a new ICB mathematical model is established by introducing pressure balance without assuming the position of the leading front to comprehensively describe the imbibition behavior in a porous medium under different conditions, including gas-liquid spontaneous imbibition and oil-water *** the pore size distribution of a tight rock is known, this new model can predict the changes of water saturation during the displacement process in the tight rock, and also determine the imbibition rate in pores of different sizes. The water saturation profiles obtained from the new model are validated against the waterflooding simulation results from the CMG, while the imbibition rates calculated by the model are validated against the experimental observations of gas-liquid spontaneous imbibition. The good match above indicates the newly proposed model can show the water saturation profile at a macroscopic scale while capture the underlying physics of the multiphase flow in a porous medium at a microscopic scale. Simulation results obtained from this model indicate that both wettability and viscosity ratio can affect the sequence of fluid imbibition into pores of different sizes during the multiphase flow, where less-viscous wetting fluid is preferentially imbibed into larger pores while more-viscous wetting fluid tends to be imbibed into smaller pores. Fur

关键词： Imbibition Multiphase flow Tight rock Interacting capillary bundle model Wettability

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Polyelectrolyte Complexes and Coacervates Formed by De novo-Designed Peptides and Oligonucleotide

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Chinese Journal of Polymer Science 2024年第9期42卷 1333-1340,I0007页

作者： Tian-hao Ren De-Hai liang Beijing National Laboratory for Molecular Sciences Department of Polymer Science and Engineering and the Key Laboratory of Polymer Chemistry and Physics of the Ministry of EducationCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871China

The liquid-liquid phase separation of biopolymers in living cells contains multiple interactions and occurs in a dynamic *** the regulation mechanism is still a *** this work,we designed a series of peptides(XXLY)_(6)SSSGSS and studied their complexation and coacervation behavior with single-stranded ***“X”and“Y”are varied to combine known amounts of charged and non-charged amino acids,together with the introduction of secondary structures and pH *** show that the electrostatic interaction,which is described as charge density,controls both the strength of complexation and the degree of chain relaxation,and thus determines the growth and size of the *** hydrophobic interaction is prominent when the charges are ***,the secondary structures of peptides exhibit profound effect on the morphology of the phases,such as solid phase to liquid phase *** study gains insight into the phase separation under physiological *** is also helpful to create coacervates with desirable structures and functions.

关键词： Polyelectrolyte complex Coacervate Peptides Secondary structure Electrostatic interaction

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The Minimum Centroid Branch Spanning Tree Problem

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Journal of the Operations Research Society of China 2024年第2期12卷 528-539页

作者： hao lin Cheng He School of Science Henan University of TechnologyZhengzhou450001HenanChina

For a spanning tree T of graph G,the centroid of T is a vertex v for which the largest component of T-v has as few vertices as *** number of vertices of this component is called the centroid branch weight of *** minimum centroid branch spanning tree problem is to find a spanning tree T of G such that the centroid branch weight is *** application to design of communication networks,the loads of all branches leading from the switch center should be as balanced as *** this paper,we prove that the problem is strongly NP-hard even for bipartite ***,the problem is shown to be polynomially solvable for split graphs,and exact formulae for special graph familis,say Kn_(1),n_(2),...,n_(k)and P_(m)×P_(n),are presented.

关键词： Spanning tree optimization Centroid branch-NP-hardness Polynomial-time algorithm

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Recent development of three-dimension printed graphene oxide and MXene-based energy storage devices

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Tungsten 2024年第1期6卷 196-211页

作者： liang-hao Yu Xin Tao Shang-Ru Feng Jin-Tao Liu lin-lin Zhang Guang-Zhen Zhao Guang Zhu Key Laboratory of Spin Electron and Nanomaterials of Anhui Higher Education Institutes Suzhou UniversitySuzhou 234000China Key Laboratory of Leather of Zhejiang Province College of Chemistry and Materials EngineeringWenzhou UniversityWenzhou 325035China

The research for three-dimension(3D)printing carbon and carbide energy storage devices has attracted widespread exploration *** designable in structure and materials,graphene oxide(GO)and MXene accompanied with a direct ink writing exhibit a promising prospect for constructing high areal and volume energy density *** review not only summarizes the recent advances in 3D printing energy storage devices including printing methods,ink rheological properties,and different energy storage systems,but also discusses the printing methods related to energy *** addition,the binder or additive free of two-dimensional carbide materials is quite important for the present electrochemical energy storage devices,which also are presented.

关键词： 3D printing Two-dimensional materials Energy storage device Ink theological MXene

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A Degree Condition for Graphs Having All(a,b)-parity Factors

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Acta Mathematicae Applicatae Sinica 2024年第3期40卷 656-664页

作者： hao-dong LIU Hong-liang LU School of Mathematics and Statistics Xi'an Jiaotong UniversityXi'an 710049China

Let a and b be positive integers such that a≤b and a≡b(mod 2).We say that G has all(a,b)-parity factors if G has an h-factor for every function h:V(G)→{a,a+2,…,b-2,b} with b|V(G)| even and h(v)≡b(mod 2) for all v∈V(G).In this paper,we prove that every graph G with n≥2(b+1)(a+b) vertices has all(a,b)-parity factors if δ(G)≥(b^(2)-b)/a,and for any two nonadjacent vertices u,v ∈V(G),max{d_(G)(u),d_(G)(v)}≥bn/a+***,we show that this result is best possible in some sense.

关键词： degree condition all(a,b)-factors

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