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Spatiotemporal mode-locked multimode fiber laser with dissipative four-wave mixing effect

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Chinese Physics B 2022年第10期31卷 165-170页

作者： Ming-Wei Qiu chao-Qun cai Zu-Xing Zhang Advanced Photonic Technology Laboratory College of Electronic and Optical Engineering&College of MicroelectronicsNanjing University of Posts and TelecommunicationsNanjing 210023China

The high degree of freedom and novel nonlinear phenomena of multimode fiber are attracting attention. In this work,we demonstrate a spatiotemporal mode-locked multimode fiber laser, which relies on microfiber knot resonance(MKR) via dissipative four-wave-mixing(DFMW) to achieve high-repetition-rate pulses. Apart from that, DFMW mode locking with switchable central wavelengths can also be obtained. It was further found that high pulse energy induced nonlinear effect of the dominant mode-locking mechanism transforming from DFMW to nonlinear Kerr beam cleaning effect(NL-KBC). The experimental results are valuable for further comprehending the dynamic characteristics of spatiotemporal mode-locked multimode fiber lasers, facilitating them much more accessible for applications.

关键词： microfiber knot resonance(MKR) dissipative four-wave-mixing(DFMW) nonlinear Kerr beam cleaning effect(NL-KBC) multimode fiber laser

Design of State Observer for Discrete-time Fault Complex Interconnected Networks with Different Nodes

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Design of State Observer for Discrete-time Fault Complex Int...

Machine learning assisted discovering of new M_(2)X_(3)-type thermoelectric materials

第25届中国控制与决策会议

作者： Zhanshan Wang chao cai Junyi Wang Hongjing Liang School of Information Science and Engineering Northeastern University

ISBN: (纸本)9781467355322

For a class of discrete-time complex interconnected networks with time-varying delay and linear coupling, a state observer is designed based on linear matrix inequality technique in order for the further design of the fault diagnosis observer in the case of un-observable system state. Then a fault diagnosis observer is designed to realize the fault detection. For the unknown uncertainty, an online approximator is designed to approximate the uncertainty, which will further help to reduce the modeling error. Stability analysis of the approximator is proved in detail. Finally, a simulation example is used to verify the validity of the presented results.

关键词： Complex interconnected networks discrete-time state observer fault diagnosis observer actuator fault

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Rare Metals 2022年第5期41卷 1543-1553页

作者： Du Chen Feng Jiang Liang Fang Yong-Bin Zhu cai-chao Ye Wei-Shu Liu Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Department of Mechanical Engineering The University of Hong KongHong Kong 999077China Department of Physics & Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and TechnologyShenzhen 518055China Key Laboratory of Energy Conversion and Storage Technologies(Ministry of Education) Southern University of Science and TechnologyShenzhen 518055China

Recent years have witnessed a continuous discovering of new thermoelectric materials which has experienced a paradigm shift from try-and-error efforts to experience-based discovering and first-principles calculation. However, both the experiment and first-principles calculation deriving routes to determine a new compound are time and resources consuming. Here, we demonstrated a machine learning approach to discover new M_(2)X_(3)-type thermoelectric materials with only the composition information. According to the classic Bi_(2)Te_(3) material, we constructed an M_(2)X_(3)-type thermoelectric material library with 720 compounds by using isoelectronic substitution, in which only 101 compounds have crystalline structure information in the Inorganic Crystal Structure Database(ICSD) and Materials Project(MP) database. A model based on the random forest(RF) algorithm plus Bayesian optimization was used to explore the underlying principles to determine the crystal structures from the known compounds. The physical properties of constituent elements(such as atomic mass, electronegativity, ionic radius) were used to define the feature of the compounds with a general formula ^(1)M^(2)M^(1)X^(2)X^(3)X(^(1)M +^(2)M:^(1)X +^(2)X+^(3)X = 2:3). The primary goal is to find new thermoelectric materials with the same rhombohedral structure as Bi_(2)Te_(3) by machine *** final trained RF model showed a high accuracy of 91% on the prediction of rhombohedral compounds. Finally, we selected four important features to proceed with the polynomial fitting with the prediction results from the RF model and used the acquired polynomial function to make further discoveries outside the pre-defined material library.

关键词： Thermoelectric materials M_(2)X_(3)-type material library Random forest(RF)algorithm Bayesian optimization Machine learning

Effect of the capsule on deformation and densification behavior of nickel-based superalloy compact during hot isostatic pressing

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International Journal of Minerals,Metallurgy and Materials 2023年第1期30卷 122-130页

作者： Lebiao Yang Xiaona Ren chao cai Pengju Xue MIrfan Hussain Yusheng Shi Changchun Ge Institute of Powder Metallurgy and Advanced Ceramics School of Materials and EngineeringUniversity of Science and Technology BeijingBeijing 100083China State Key Laboratory of Materials Processing&Die and Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

The Shima yield criterion used in finite element analysis for nickel-based superalloy powder compact during hot isostatic pressing(HIP) was modified through uniaxial compression experiments. The influence of cylindrical capsule characteristics on FGH4096M superalloy powder compact deformation and densification behavior during HIP was investigated through simulations and experiments. Results revealed the simulation shrinkage prediction fitted well with the experimental shrinkage including a maximum shrinkage error of 1.5%. It was shown that the axial shrinkage was 1.7% higher than radial shrinkage for a cylindrical capsule with the size of ∮50 mm × 100 mm due to the force arm difference along the axial and radial direction of the capsule. The stress deviated from the isostatic state in the capsule led to the uneven shrinkage and non-uniform densification of the powder compact. The ratio of the maximum radial displacement to axial displacement increased from0.47 to 0.75 with the capsule thickness increasing from 2 to 4 mm. The pressure transmission is related to the capsule thickness, the capsule material performance, and physical parameters in the HIP process.

关键词： hot isostatic pressing nickel-based superalloy compact capsule densification deformation

Response of bacterial communities to short-term pyrene exposure in red soil

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Frontiers of Environmental Science & Engineering 2013年第4期7卷 559-567页

作者： Jingjing PENG Hong LI Jianqiang SU Qiufang ZHANG Junpeng RUI chao cai Key Laboratory of Urban Environment and Health Institute of Urban Environment Chinese Academy of Sciences Xiamen 361021 China Lancaster Environment Centre Lancaster University Lancaster LA1 4YQ UK College of Resources and Environmental Sciences China Agricultural University Beijing 100193 China

Pyrene, a representative polycyclic aromatic hydrocarbon （PAH） compound produced mainly from incomplete combustion of fossil fuels, is hazardous to ecosystem health. However, long-term exposure studies did not detect any significant effects of pyrene on soil microorganism. In this study, short-term microcosm experiments were conducted to identify the immediate effect of pyrene on soil bacterial communities. A freshly- collected pristine red soil was spiked with pyrene at 0, 10, 100, 200, and 500 ***-~ and incubated for one day and seven days. The bacterial communities in the incubated soils were analyzed using 16S rRNA sequencing and terminal restriction fragment length polymorphism （T- RFLP） methods. The results revealed high bacterial diversity in both unspiked and pyrene-spiked soils. Only at the highest pyrene-spiking rate of 500 ***-~, two minor bacteria groups of the identified 14 most abundant bacteria groups were completely suppressed. Short-term exposure to pyrene resulted in dominance of Proteobac- teria in soil, followed by Acidobacteria, Firmutes, and Bacteroidetes. Our findings showed that bacterial commu- nity structure did respond to the presence of pyrene but recovered rapidly from the perturbation. The intensity of impact and the rate of recovery showed some pyrene dosage-dependent trends. Our results revealed that differ- ent levels of pyrene may affect the bacterial community structure by suppressing or selecting certain groups of bacteria. It was also found that the bacterial community was most susceptible to pyrene within one day of the chemical addition.

关键词： pyrene bacterial communities terminalrestriction fragment length polymorphism short-term

Tailorable microstructure and mechanical properties of selective laser melted TiB/Ti-6Al-4V composite by heat treatment

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Advanced Powder Materials

Advanced Powder Materials 2022年第2期1卷 19-26页

作者： Jinliang Zhang Bo Song chao cai Lijun Zhang Yusheng Shi State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan430074China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083China

This paper systematically investigated the effect of solution and artificial aging heat treatments on the microstructural evolution and mechanical properties of TiB/Ti-6Al-4V composites in situ fabricated by selective laser *** results showed that the fully martensite microstructure with TiB clusters of the as-built samples was transformed into lamellarα+βmicrostructure with TiB strips after solution heat *** increasing the temperature,theαlaths and TiB particles coarsened and theβvolume fraction *** aging heat treatment,βvolume fraction decreased and TiB had no obvious changes.A superior combination of the yield strength of(1146.8±28.2)MPa and even higher plasticity and ultimate compressive strength((1680.1±18.3)MPa)than the as-built ones was obtained by solution heat treatment at 1000℃+water quenching and aging at 600℃for 6 hþair cooling.

关键词： TiB/Ti-6Al-4V composite Selective laser melting Heat treatment Microstructure Mechanical properties

A new facile synthesis of shikalkin

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Chinese Chemical Letters 2008年第2期19卷 172-174页

作者： Qun Lu Hao Lun Tang Yan Qiang Shao Jun chao cai Department of Bioengineering Southwest Jiaotong University Chengdu 610031 China Shanghai Institute of Materia Medica Chinese Academy of Sciences Shanghai 200031 China

A short and convergent approach for the synthesis of shikalkin （dl-shikonin） is presented. Stobbe reaction was employed to construct the aromatic skeleton 6. This is followed by a practical method to prepare the key... 详细信息

关键词： Synthesis Shikalkin Epoxides

气候变化下山西某风电项目未来风能资源的评估

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中外能源 2025年第3期30卷 21-29页

作者：蔡超李美姗高雪琴许嘉钰清华大学环境学院北京100084 北京三易思创科技有限公司北京100020 悉尼大学澳大利亚新南威尔士州悉尼NSW 2006

目前针对未来风能资源变化的研究,主要为全球或全国的大尺度范围。利用WRF/CALMET耦合模式对山西某风电项目进行降尺度模拟,选取2010年、2022年、2035年、2060年4个年份,以该项目区域范围内风速最大的5月份和风速最小的8月份作为典型月... 详细信息

目前针对未来风能资源变化的研究,主要为全球或全国的大尺度范围。利用WRF/CALMET耦合模式对山西某风电项目进行降尺度模拟,选取2010年、2022年、2035年、2060年4个年份,以该项目区域范围内风速最大的5月份和风速最小的8月份作为典型月份,计算其风速和风功率密度,分析历史和未来场景下风能资源的变化趋势。结果表明:在历史场景下,模拟结果相比实测数据偏大,其中月平均风速整体偏差1.34m/s,均方根误差为1.62m/s;风功率密度整体偏差185W/m^(2),均方根误差为196W/m^(2)。但二者变化趋势相似,可以反映项目范围内风能资源的变化趋势。在未来SSP126场景(低强迫情景)下,不同月份风能资源有不同的变化趋势,其中5月风速和风功率密度有增大趋势,而8月则有减小趋势,且高度越高,增大或减小趋势越明显。气候变化引起亚洲地区春季海陆气压差变大、夏季海陆气压差变小,从而解释了5月和8月风能资源变化趋势不一致的原因。WRF/CALMET模式结合CMIP6未来气候数据,可以对风电项目未来风能资源的变化趋势进行更为细致地评估,为风电机组选址提供科学依据。

关键词：风能资源评估风速风功率密度气候变化 WRF/CALMET 耦合模式

Determination of dynamic capillary effect on two-phase flow in porous media: A perspective from various methods

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Petroleum Science 2022年第4期19卷 1641-1652页

作者： Jian-chao cai Yin Chen Jun-Cheng Qiao Liu Yang Jian-Hui Zeng Chen-Hao Sun State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249PR China Institute of Geophysics and Geomatics China University of GeosciencesWuhan430074HubeiPR China State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and Technology(Beijing)Bejing100083PR China

The relationship between capillary pressure and saturation plays a critical role in the characterization of two-phase flow and transport in aquifers and oil reservoirs. This relationship is usually determined under the static condition, where capillary pressure is the only function of saturation. However,considerable experiments have suggested that the dependence of capillary pressure on desaturation rate is under the dynamic condition. Thus, a more general description of capillary pressure that includes dynamic capillary effect has been approved widely. A comprehensive understanding of the dynamic capillary effect is needed for the investigation of the two-phase flow in porous media by various methods. In general, dynamic capillary effect in porous media can be studied through the laboratory experiment, pore-to macro-scale modeling, and artificial neural network. Here, main principle and research procedures of each method are reviewed in detail. Then, research progress, disadvantages and advantages are discussed, respectively. In addition, upscaling study from pore-to macro-scale are introduced, which explains the difference between laboratory experiment and pore-scale modeling. At last, several future perspectives and recommendations for optimal solution of dynamic capillary effect are presented.

关键词： Dynamic capillary effect Capillary pressure Two-phase flow Modeling method