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Spanning tree trajectory optimization in the galaxy space

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Astrodynamics 2021年第1期5卷 27-37页

作者： tian-jiao zhang Dietmar Wolz Hong-Xin Shen Ya-Zhong Luo State Key Laboratory of Astronautic Dynamics Xi’an Satellite Control CenterXi’an 710043China University of Jena Jena 07737Germany National University of Defense Technology Changsha 410073China

The 10th edition of the Global Trajectory Optimization Competition considered the problem of the galaxy settlement wherein competitors from all over the world were expected to design the trajectories of different settler vessels to maximize the given multi-faceted merit *** synthesis methods used by the winning team,led jointly by the National University of Defense Technology(NUDT)and Xi’an Satellite Control Center(XSCC),are described along with a greedy search method and the improved solution obtained by University of ***,we presented a layout-first topology-second approach that allows an efficient settlement tree search guided by the pre-specified ideal spatial *** also explained how the problem of constructing settlement trees can be modeled as the widely studied minimum spanning tree ***,University of Jena explored the possibility that a greedy search can generate even better settlement trees,based on the same initial conditions,when compared to that of the winning solution.

关键词： trajectory optimization Settlers of the Galaxy minimum spanning tree ant colony optimization greedy search

Explosion characteristics of aluminum-based activated fuels containing fluorine

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Defence Technology（防务技术） 2023年第2期20卷 34-43页

作者： Jin-tao Xu Lei Huang Hai-peng Jiang tian-jiao zhang Feng-qi Zhao Jian-kan zhang Wei Gao State Key Laboratory of Fine Chemicals Department of Chemical Machinery and Safety EngineeringDalian University of TechnologyDalian116024China Beijing Institute of Aerospace Testing Technology Beijing100074China Science and Technology on Combustion and Explosion Laboratory Xi'an Modern Chemistry Research InstituteXi'an710065China

Measuring the dust explosion characteristics of aluminum-based activated fuels was a prerequisite for developing effective prevention and control *** this paper,ignition sensitivity,flame propagation behaviors and explosion severity of aluminum/polytetrafluoroethylene(Al/PTFE)compositions including 2 PT(2.80 wt.%F),4 PT(7.18 wt.%F)and 8 PT(11.90 wt.%F)were *** the content of F increased from 2.80 wt.%to 11.90 wt.%,the minimum explosive concentration MEC decreased from380 g/m^(3)to 140 g/m^(3),due to the dual effects of increased internal active aluminum and enhanced *** average flame propagation velocities increased as the percentage of F *** maximum explosion pressure Pmof 500 g/m3aluminum-based activated fuels increased from 247 k Pa to299 *** electron microscopy demonstrated that with the increase of PTFE content,the reaction was more *** this basis,the explosion mechanism of aluminum-based activated fuels was revealed.

关键词： Aluminum-based activated fuels Ignition sensitivity Flame propagation Explosion severity Explosion mechanism

Unsteady aerodynamics modeling for flight dynamics application

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Acta Mechanica Sinica 2012年第1期28卷 14-23页

作者： Qing Wang Kai-Feng He. Wei-Qi Qian tian-jiao zhang Yan-Qing Cheng Kai-Yuan Wu State Key Laboratory of Aerodynamics 621000 MianyangChina Computational Aerodynamics Institute China Aerodynamics Research and Development Center621000 MianyangChina Scientific Research Base of Flight Technology and Safety Civil Aviation Flight University of China618307 GuanghanChina

In view of engineering application, it is practicable to decompose the aerodynamics into three components： the static aerodynamics, the aerodynamic increment due to steady rotations, and the aerodynamic increment due to unsteady separated and vortical flow. The first and the second components can be presented in conventional forms, while the third is described using a one-order differential equation and a radial-basis-function （RBF） network. For an aircraft configuration, the mathematical models of 6- component aerodynamic coefficients are set up from the wind tunnel test data of pitch, yaw, roll, and coupled yawroll large-amplitude oscillations. The flight dynamics of an aircraft is studied by the bifurcation analysis technique in the case of quasi-steady aerodynamics and unsteady aerodynam- ics, respectively. The results show that：（1） unsteady aerodynamics has no effect upon the existence of trim points, but affects their stability; （2） unsteady aerodynamics has great effects upon the existence, stability, and amplitudes of periodic solutions; and （3） unsteady aerodynamics changes the stable regions of trim points obviously. Furthermore, the dynamic responses of the aircraft to elevator deflections are inspected. It is shown that the unsteady aerodynamics is beneficial to dynamic stability for the present aircraft. Finally, the effects of unsteady aerodynamics on the post-stall maneuverability

关键词： Unsteady aerodynamics High angle of attack Mathematical model Flight dynamics - Bifurcation analysis Post-stall maneuver

Cofitness network connectivity determines a fuzzy essential zone in open bacterial pangenome

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mLife 2024年第2期3卷 277-290页

作者： Pan zhang Biliang zhang Yuan-Yuan Ji Jian jiao Ziding zhang Chang-Fu tian State Key Laboratory of Plant Environmental Resilience and College of Biological SciencesChina Agricultural UniversityBeijingChina MOA Key Laboratory of Soil Microbiology and Rhizobium Research CenterChina Agricultural UniversityBeijingChina Shenzhen Institute of Synthetic Biology Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhenChina State Key Laboratory of Livestock and Poultry Biotechnology Breeding and College of Biological SciencesChina Agricultural UniversityBeijingChina

Most in silico evolutionary studies commonly assumed that core genes are essential for cellular function,while accessory genes are dispensable,particularly in nutrient-rich ***,this assumption is seldom tested genetically within the pangenome *** this study,we conducted a robust pangenomic Tn-seq analysis of fitness genes in a nutrient-rich medium for Sinorhizobium strains with a canonical open *** evaluate the robustness of fitness category assignment,Tn-seq data for three independent mutant libraries per strain were analyzed by three methods,which indicates that the Hidden Markov Model(HMM)-based method is most robust to variations between mutant libraries and not sensitive to data size,outperforming the Bayesian and Monte Carlo simulation-based ***,the HMM method was used to classify the fitness *** genes,categorized as essential(ES),advantage(GA),and disadvantage(GD)genes for growth,are enriched in core genes,while nonessential genes(NE)are over-represented in accessory *** ES/GA genes showed a lower fitness effect than core ES/GA *** degrees in the cofitness network decrease in the order of ES,GD,and GA/*** addition to accessory genes,1599 out of 3284 core genes display differential essentiality across test *** the pangenome core,both shared quasi-essential(ES and GA)and strain-dependent fitness genes are enriched in similar functional *** analysis demonstrates a considerable fuzzy essential zone determined by cofitness connectivity degrees in Sinorhizobium pangenome and highlights the power of the cofitness network in understanding the genetic basis of ever-increasing prokaryotic pangenome data.

关键词： cofitnessnetwork pangenome Tn-seq

A Possible γ-Ray Pulsation from PSR J1740-5340B in the Globular Cluster NGC 6397

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Research in Astronomy and Astrophysics 2024年第1期24卷 285-291页

作者： jiao Zheng Pengfei zhang Li zhang Department of Astronomy School of Physics and AstronomyKey Laboratory of Astroparticle Physics of Yunnan ProvinceYunnan UniversityKunming 650091China

Recently, a new radio millisecond pulsar(MSP) J1740-5340B, hosted in the globular cluster(GC) NGC 6397,was reported with a 5.78 ms spin period in an eclipsing binary system with a 1.97 days orbital period. Based on a modified radio ephemeris updated by tool tempo2, we analyze the ~15 yr γ-ray data obtained from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope and detect PSR J1740-5340B's γ-ray pulsation at a confidence level of ~4σ with a weighted H-test value of ~26. By performing a phase-resolved analysis, the γ-ray luminosity in on-pulse interval of PSR J1740-5340B is L_(γ)~ 3.8 × 10^(33) erg s^(-1) using NGC 6397's distance of 2.48 kpc. And γ-rays from the on-pulse part of PSR J1740-5340B contribute ~90% of the total observed γ-ray emissions from NGC 6397. No significant γ-ray pulsation of another MSP J1740-5340A in the GC is *** that the previous four cases of MSPs in GCs, more data in γ-ray, X-ray, and radio are encouraged to finally confirm the γ-ray emissions from MSP J1740-5340B, especially starving for a precise ephemeris.

关键词： gamma-rays:galaxies (stars:)pulsars:individual(PSR J1740-5340B) (Galaxy:)globular clusters:individual(NGC 6397)

Robust adaptive radar beamforming based on iterative training sample selection using kurtosis of generalized inner product statistics

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Journal of Systems Engineering and Electronics 2024年第1期35卷 24-30页

作者： tian Jing zhang Wei School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China National Key Laboratory of Electromagnetic Space Security Chengdu 610036China

In engineering application,there is only one adaptive weights estimated by most of traditional early warning radars for adaptive interference suppression in a pulse reputation interval(PRI).Therefore,if the training samples used to calculate the weight vector does not contain the jamming,then the jamming cannot be removed by adaptive spatial *** the weight vector is constantly updated in the range dimension,the training data may contain target echo signals,resulting in signal cancellation *** cope with the situation that the training samples are contaminated by target signal,an iterative training sample selection method based on non-homogeneous detector(NHD)is proposed in this paper for updating the weight vector in entire range *** principle is presented,and the validity is proven by simulation results.

关键词： adaptive radar beamforming training sample selection non-homogeneous detector electronic jamming jamming suppression

Detection of Increasingγ-Ray Emissions from 4FGL J1718.5+4237 with Fermi-LAT

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Research in Astronomy and Astrophysics 2024年第8期24卷 169-174页

作者： jiao Zheng Pengfei zhang Li zhang Department of Astronomy School of Physics and AstronomyKey Laboratory of Astroparticle Physics of Yunnan ProvinceYunnan UniversityKunming 650091China School of Physics and Engineering Technology Xingyi Normal University for NationalitiesXingyi 562400China

We report a gradual brighteningγ-ray source,4FGL J1718.5+4237,in 0.1-500.0 GeV,which may be associated with a blazar NVSS J171822+423948 with a redshift of~*** analyzed 15.25 yr ofγ-ray data recorded by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope and detected significantγ-ray emissions in the direction of the blazar with a test statistic(TS)of~*** on timing analysis using a 1 yr time bin,we have observed a gradual brightening inγ-ray emissions from the *** our analysis,we categorize them into two states:Quiet(TS~0)and Loud(TS~226)states,with the distinction occurring in 2016 August(MJD57602.69).From the Quiet state to the brightest period(the last data point),theγ-ray flux in 0.1-500.0 GeV increased by more than 12-fold from<0.2×10^(-8)photons cm^(-1)s^(-1)to 2.6×10^(-8)photons cm^(-1)s^(-1).Additionally,we studied the spectral properties in detail for the Loud state and the overall *** no significant variation was detected,both exhibited a spectral indexΓof~*** origin of the brighteningγ-ray emissions from the target is not yet *** long-term multi-wavelength observations and studies will provide insight into the astrophysical mechanisms of the target.

关键词： galaxies active-blazars individual(4FGL J1718.5+4237)

Frequency Domain Fatigue Evaluation on SCR Girth-Weld Based on Structural Stress

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China Ocean Engineering 2024年第2期38卷 255-270页

作者： zhang Long ZHAO tian-feng College of Safety and Ocean Engineering China University of Petroleum(Beijing)Beijing 102249China

The Steel Catenary Riser(SCR)is a vital component for transporting oil and gas from the seabed to the floating *** harsh environmental conditions and complex platform motion make the SCR’s girth-weld prone to fatigue *** structural stress fatigue theory and Master S-N curve method provide accurate predictions for the fatigue damage on the welded joints,which demonstrate significant potential and compatibility in multi-axial and random fatigue ***,we propose a new frequency fatigue model subjected to welded joints of SCR under multiaxial stress,which fully integrates the mesh-insensitive structural stress and frequency domain random process and transforms the conventional welding fatigue technique of SCR into a spectrum analysis technique utilizing structural ***,a full-scale FE model of SCR with welds is established to obtain the modal structural stress of the girth weld and the frequency response function(FRF)of modal coordinate,and a biaxial fatigue evaluation about the girth weld of the SCR can be achieved by taking the effects of multi-load correlation and pipe-soil interaction into *** research results indicate that the frequency-domain fatigue results are aligned with the time-domain results,meeting the fatigue evaluation requirements of the SCR.

关键词： SCR girth weld random vibration self(cross)power spectrum structural stress method biaxial fatigue damage

Investigation and Analysis of Hemoglobin Alc Measurement Systems＇ Performance for 135 Laboratories in China

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Chinese Medical Journal 2017年第9期130卷 1079-1084页

作者： Hai-Jian Zhao tian-jiao zhang Jie Zeng Cui-Hua Hu Rong Ma Chuan-Bao zhang National Center for Clinical Laboratories Beijing Hospital National Center of Gerontology Beijing Engineering Research Center of Laboratory Medicine Beijing 100730 China

Background： Hemoglobin A 1 c （HbA1 c） measurement is of great value for the diagnosis and monitoring of diabetes. Many manufacturers have developed various experiments to determine the HbAlc concentration. However, the longitudinal use of these tests requires strict quality management. This study aimed to analyze the quality of HbAlc measurement systems in China using six sigma techniques to help improve their performances. Methods： A total of 135 laboratories were involved in this investigation in 2015. Bias values and coefficients of variation were collected from an HbA 1 c trueness verification external quality assessment program and an internal quality control program organized by the National Center of Clinical Laboratories in China. The sigma （σ） values and the quality goal index （QGI） were used to evaluate the performances of different groups, which were divided according to principles and instruments. Results： The majority of participants （88, 65.2%） were scored as ＂improvement needed （σ 〈 3）＂, suggesting that the laboratories needed to improve their measurement performance. Only 8.2% （11/135） of the laboratories were scored as ＂world class （σ≥ 6）＂. Among all the 88 laboratories whose σ values were below 3, 52 （59.1%） and 23 （26.1%） laboratories needed to improve measurement precision （QGI 〈8.0） and trueness （QGI 〉 1.2）, respectively; the remaining laboratories （13, 14.8%） needed to improve both measurement precision and trueness. In addition, 16.1% （5/31） and 15.0% （3/20） of the laboratories in ＂TO SOH＂ and ＂ARKRAY＂ groups, respectively, were scored as ＂world class＂, whereas none of the laboratories in ＂BIO-RAD＂ group were scored as ＂world class＂. Conclusions： This study indicated that, although participating laboratories were laboratories with better performance in China, the performances were still unsatisfactory. Actions should be taken to improve HbAlc measurement performance before we can include HbAlc assays in diabetes diagnosis in China.

关键词： Hemoglobin Alc Quality Assurance Six Sigma Metric