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Mesospheric tide comparisons at low latitudes observed by two collocated meteor radars

Earth and Planetary Physics 2025年第1期9卷 54-68页

作者： Jian Li Wen Yi XiangHui Xue Jie zeng HaiLun Ye JianYuan Wang JinSong Chen Na Li TingDi Chen Chinese Academy of Sciences(CAS)Key Laboratory of Geospace Environment Department of Geophysics and Planetary SciencesUniversity of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Comparative Planetology Anhui Mengcheng Geophysics National Observation and Research StationUniversity of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230026China Collaborative Innovation Center of Astronautical Science and Technology Harbin 150001China National Key Laboratory of Electromagnetic Environment China Research Institute of Radiowave PropagationQingdao 266107China Yunnan Kunming Electromagnetic Environment National Observation and Research Station Qujing Kunming 655000China

Accurate knowledge of mesospheric winds and waves is essential for studying the dynamics and climate in the mesosphere and lower thermosphere(MLT)*** this study,we conduct a comparative analysis of the mesosphere tidal results obtained from two adjacent meteor radars at low latitudes in Kunming,China,from November 2013 to December *** two radars operate at different frequencies of 37.5 MHz and 53.1 MHz,***,overall good agreement is observed between the two radars in terms of horizontal winds and tide *** results show that the dominant tidal waves of the zonal and meridional winds are diurnal and semidiurnal ***,we conduct an exhaustive statistical analysis to compare the tidal amplitudes and vertical wavelengths recorded by the dual radar systems,which reveals a high degree of alignment in tidal *** investigation includes variances and covariances of tidal amplitudes,which demonstrate remarkable consistency across measurements from both *** finding highlights clear uniformity in the mesospheric tidal patterns observed at low latitudes by the two neighboring meteor *** of the comparative analysis specifically underscore the significant correlation in vertical wavelength measurements,validating the robustness of radar observations for tidal research.

关键词： mesosphere and lower thermosphere region meteor radar mesospheric winds tides

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Optimization of reluctance accelerator efficiency by an improved discharging circuit

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Defence Technology（防务技术） 2020年第3期16卷 662-667页

作者： Hui-min Deng Yu Wang fa-long Lu Zhong-ming Yan School of Electrical Engineering Southwest Jiaotong UniversityChengdu610031China

In this paper,an improved discharging circuit was proposed to quicken the decay of the current in the drive coil in a reluctance accelerator when the armature reaches the center of the *** aim of this is to prevent the suck-back effect caused by the residual current in drive *** method is adding a reverse charging branch with a small capacitor in the traditional pulsed discharging *** results under the traditional circuit and the improved circuit were compared in a *** experiment then verified the simulations and they had good *** and experiment both demonstrated the improved circuit can effectively prevent the suck-back effect and increase the *** the voltage of 800 V,an efficiency increase of 36.34% was obtained.

关键词： Reluctance accelerator Suck-back effect Discharging circuit Current decay Efficiency optimization

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Cloning of Salt Tolerance-Related cDNAs from the Mangrove Plant Sesuvium portulacastrum L.

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Journal of Integrative Plant Biology 2006年第8期48卷 952-957页

作者： Hui-Cai zeng Liu-Hong Deng Chun-fa Zhang State Key Laboratory of Tropical Crop Biotechnology Institute of Tropical Bioscience and Biotechnology Chinese Academy of Tropical Agricultural Science （ CATAS） Kaikou 571101 China Environmental and Plant Protection Institute CATAS Danzhou 571737 China

In an attempt to isolate and identify the target genes relevant to salt tolerance in a mangrove plant （Sesuvium portulacastrum L.）, a subtracted cDNA library was constructed via suppressive subtractive hybridization （SSH）, in which the poly（A）＋RNA isolated from salt-tolerant S. portulacastrum leaves was used as a tester, whereas the driver was poly（A）＋RNA, derived from salt-sensitive S. portulacastrum leaves. Screening of this subtracted cDNA library revealed five clones, of which the expression levels in the salt-tolerant plant were markedly higher than those observed in the salt-sensitive plant, indicating that these candidate clones may be involved in salt-tolerance pathways. Among the clones isolated, P66, P175, and P233 are novel because no significant similarity was obtained upon alignment with the GenBank database. Clone P89 demonstrated high homology with NADPH of Arabidopsis thaliana, whereas clone P152 was highly homologous with the gene encoding late embryogenesis abundant （LEA） protein of A. thaliana. The full-length gene of clone P152, with a predicated 344 amino acid residues, was shown to bear LEA-2 domains, a signature motif for proteins that have been enriched under salty and drought conditions. It is thus implied that clone P152 would be a salt-tolerance gene of S. portulacastrum. In addition, we have also developed a strategy for the extraction of total RNA from mangrove plants.

关键词： mangrove salt tolerance-related cDNAs Sesuvium portulacastrum suppressive subtractive hybridization.

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Evolution Behavior of γ-Al_(3.5)FeSi in Mg Melt and a Separation Method of Fe from Al–Si–Fe Alloys

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Acta Metallurgica Sinica(English Letters) 2018年第1期31卷 48-54页

作者： Tong Gao zeng-Qiang Li Yao-Xian Zhang Xiang-fa Liu Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials Ministry of Education Shandong University

The recycling of high Fe-content Al-Si alloys is a green industry. Eliminating the harmful effect of Fe, achieving the separation of Al and Fe is one of the key problems. Different from traditional methods for iron removal, a novel method using magnesium melt to separate Al and Fe is proposed. By introducing Al-14Si-5Fe alloy into Mg melt, it was found that the γ-Al3.5FeSi phase evolves to Al3SiFe3.5 and Al5Fe2 through the melting and solidification process. Compared with the primary Al-rich γ-Al3.5FeSi phase, the formation of Fe-rich A13SiFe3.5 is quite beneficial for the separation of Al and Fe. Mg-Si-Al and Mg-Si-Fe alloys can be obtained at the top and bottom of the cooled ingot, respectively. The results in this study provide meaningful suggestions for recycling scrap Al-Si-Fe materials.

关键词： Al-Si-Fe Mg melt Fe-rich phase evolution Separation

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Growth behavior of spinel in stainless steel slag during cooling process

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Journal of Iron and Steel Research International 2018年第11期25卷 1131-1139页

作者： long-hu Cao Cheng-jun Liu Qing Zhao Mao-fa Jiang Key Laboratory for Ecological Metallurgy of Multimetallic Ores (Ministry of Education) Northeastern University Shenyang 110819LiaoningChina School of Metallurgy Northeastern University Shenyang 110819LiaoningChina

Spinel is an appropriate phase for sequestrating chromium in stainless steel slag to prevent chromium from polluting,and the crystal size of spinel has a significant effect on the stability of chromium and the extraction efficiency of *** enrichment behavior of chromium in spinel during cooling process was investigated,and the growth process of spinel was studied based on the crystal size distribution *** results showed that the enrichment degree of chromium in spinel increased from 88.5% to nearly 100% during the cooling process from 1773 to 1573 K at a rate of 5 K/*** mean diameter of spinel in stainless steel slag had an obvious growth in the cooling process,and a rapid growth of spinel occurred during the cooling process from 1623 to 1523 *** results indicated that the leaching amount of chro- mium could reduce to less than 0.01 mg/L by controlling the cooling *** growth mechanism of spinel was investigated and proposed to consist of two stages:in the first stage,the spinel was in the surface-controlled growth with a decaying nucleation rate from 1773 to 1573 K,and in the second stage,the growth mechanism was transformed to supply- controlled Ostwald ripening-below 1573 K.

关键词： Stainless steel slag Spinel Chromium Growth mechanism Crystal size distribution

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Effect of Al2O3 modification on enrichment and stabilization of chromium in stainless steel slag

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Journal of Iron and Steel Research International 2017年第3期24卷 258-265页

作者： long-hu Cao Cheng-jun Liu Qing Zhao Mao-fa Jiang Key Laboratory for Ecological Metallurgy of Multimetallic Mineral (Ministry of Education) Northeastern University Shenyang 110819 Liaoning China

Spinel phase is considered to be the optimal phase for stabilization of chromium in stainless steel *** order to restrain chromium leaching from slag for the effective environmental protection,Al2O3 was utilized for the modification treatment,and the effects on the enrichment and stabilization of chromium were investigated. The mineral phases and the existence state of chromium in slag with various Al2O3 contents at different basicities（ w（CaO）/w（SiO2） were analyzed by scanning electron microscopy-energy dispersive spectroscopy（ SEM-EDS） and X-ray diffraction（ XRD）. The results showed that chromium mainly existed in the glass and spinel phases at basicity of 1. 0 and 1. 5. As the slag basicity increased to 2. 0,chromium was also found in periclase phase. Al2O3 in the stainless steel slag reacted with MgO and Cr2O3,which could generate the Al-rich Mg（CrxAl（1- x））2O4 solid solution. Moreover,the addition of Al2O3 was favorable to reduce the solubility of chromium oxide in liquid phase and suppress the precipitation of periclase phase. The experimental results demonstrated that Al2O3 modification has a positive influence on the enrichment and the stabilization of chromium in the stainless steel slag.

关键词： Stainless steel slag Chromium Spinel Al2O3 modification Enrichment Stabilization

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A comprehensive understanding of grain selection in spiral grain selector during directional solidification

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Journal of Materials Science & Technology 2022年第7期102卷 204-212页

作者： Binqiang Wang long zeng Neng Ren Mingxu Xia Jianguo Li School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China

It is of great importance to further investigate grain selection mechanism for the production of single crystal(SX) turbine blade because a single crystal with optimized crystal orientation will enhance service performance of the blade *** this paper,single crystals with different deviation angles,i.e.6°,12° and 29°, were obtained using directional solidification under the same casting *** has been found that the grain selection in spiral selector is a coupling process where high order dendrites branch in the front side and primary dendrites disappear in the back side based on the metallographic analysis and electron back scatter diffraction(EBSD).Considering the development of liquid/solid interface by numerical simulation,a combination effect with space expansion,geometrical restriction and grain competition was proposed for spiral grain *** space expansion mechanism dominates the process as it provides growth space and driving force for high order dendrites ***,the smaller the take-off angle(θ) is,the larger space and the stronger driving force high order dendrites will get,and the higher efficient the selector will be. The competitive growth between the secondary dendrites plays more contribution than that of primary dendrites,*** with preferred secondary dendrites instead of preferred primary dendrites could outcompete during grain selection,and this is the reason why spiral grain selector cannot optimize the orientation of the primary *** findings provide experimental evidence for spatial control of SX growth,and benefit the sophistic casting fields such as turbine blade casting for improved yield.

关键词： Ni-based superalloy Spiral grain selector Space expansion Geometrical restriction Grain competition

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Ni-catalyzed cross-electrophile alkyl-alkyl coupling reactions

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Science China Chemistry 2025年

作者： Li-Xu You Lan Tian Chun-Ling Guo Shun-Xi Li Yu-Cheng Liu Yu-long Li Wei Shu College of Chemistry and Environmental Engineering Key Laboratory of Green Catalysis of Higher Education Institutes of Sichuan Sichuan University of Science and Engineering Guangming Advanced Research Institute Shenzhen Grubbs Institute Department of Chemistry and Guangdong Provincial Key Laboratory of Catalysis Southern University of Science and Technology

Introducing saturated carbon-carbon bonds into organic molecules significantly increases the three-dimensional configuration,thus altering the physical and chemical properties as well as the functions of molecules. Transition-metal-catalyzed carboncarbon cross-couplings represent one of the most straightforward, efficient and modular alternatives to build saturation in a single step. However, the efficient construction of alkyl-alkyl bonds remains a formidable challenge due to the precise manipulation of multiple alkyl metallic intermediates as well as associated competitive side reactions and selectivity control. Over the past years, Ni-catalyzed cross-coupling under reductive conditions has gained more and more attention for alkyl-alkyl crosscoupling partially attributing to the low-valent state of metal centers under reducing conditions, which suppresses the competitive β-hydride elimination process, thus facilitating the formation of alkyl-alkyl bonds. In this review, the initiative and progress of Ni-catalyzed cross-electrophile alkyl-alkyl cross-coupling, including the efforts in racemic and enantioselective formation of alkyl-alkyl bonds, have been summarized and discussed. Moreover, the challenges and further opportunities in this area have also been discussed.

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The possibility of isolated target 3-D position estimation and optimal receiver position determination in SS-BSAR

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Science in China(Series F) 2008年第9期51卷 1372-1383页

作者： HU Cheng long Teng zeng Tao Radar Research Lab Department of Electronic Engineering Beijing Institute of Technology Beijing 100081China

Starting from the generalized ambiguity function of bistatic SAR （BSAR）, it is shown that 3-D point target estimation can be carried out in space-surface bistatic SAR （SS-BSAR）. Appropriate analytical equations, based on maximum likelihood estimation （MLE）, are derived and confirmed via computer simulation. Furthermore, the performance of the estimate using the Crammer-Rao bound is analyzed for the case in question, thus further revealing the possibility and potential of target 3-D position estimation. Setting the determinant maximum of the information matrix as the criterion, the optimal receiver position and multi-receiver configuration are analytically determined in the SS-BSAR system. Simulation results also validate the correctness of the analytical calculation.

关键词： SS-BSAR position estimation MLE Crammer-Rao bound optimal receiver position

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Risks analysis of large diameter slurry shield tunneling in urban area

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Underground Space 2023年第6期13卷 281-300页

作者： Yi zeng Pierre Guy Atangana Njock Wang Xiong Xiao-long Zhang Shui-long Shen Shanghai Tunnel Engineering&Rail Transit Design and Research Institute Shanghai 200235China Department of Civil and Environmental Engineering College of EngineeringShantou UniversityShantouGuangdong 515063China MOE Key Laboratory of Intelligence Manufacturing Technology Department of Civil and Environmental EngineeringCollege of EngineeringShantou UniversityShantouGuangdong 515063China

The construction of super-large tunnels generates various safety risks that can hamper the tunneling process and cause severe damages if not properly *** paper presents a case study on the identification and management of geological and environmental risks during the construction of the largest(a diameter of 15.8 m)slurry shield tunnel in *** ground conditions and settlement control were identified among the most challenging owing to a large area of mixed ground conditions,11 fault zones and tunneling under residential areas and the city’s Metro Lines 1 and *** response to the severity of these risks and challenges,novel monitoring systems,ground treatment,and safety management technologies were successfully implemented throughout the tunneling ***,a technical framework was proposed in this study to serve as a risk management guidance for analogous tunneling operations.

关键词： Large diameter Risks Shield tunneling fault zones Geohazard mitigation

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