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Switching,explosion,and chaos of multi-wavelength soliton states in ultrafast fiber lasers

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 82-90页

作者： Zhi-Zeng Si Yue-Yue Wang Chao-qing dai College of Optical Mechanical and Electrical EngineeringZhejiang A&F UniversityLin’an 311300China

Because of the complexity and difficulty of realizing a multi-wavelength soliton state,reports on its internal dynamic characteristics are *** this study,the switching and periodic soliton explosion processes of the multi-wavelength soliton state in a negative dispersion passively mode-locked fiber laser are *** generation of the multi-wavelength soliton state undergoes the process of noise,oscillation,and stable mode-locking,and the splitting and annihilation of solitons with different group velocities directly impact the generation and disappearance of three *** and negative dispersion lead to different group velocities of *** presence and displacement of solitons with different group velocities cause soliton collisions,which lead to soliton explosions.A soliton experiences relative phase oscillation,chaos,and oscillation,as well as convergence and separation before and after an *** an increase in parameters related to pump power,single-soliton oscillation,multi-wavelength solitons,and chaos are found in experiments and simulations,proving the relevance and reliability between simulation and experimental *** work promotes the dynamical study of multi-soliton collisions in nonlinear science and the development of chaos theory in multi-comb lasers.

关键词： multi-wavelength fiber laser soliton explosion chaos state switching real-time dynamics

Flow field effect of delayed neutron precursors in liquid-fueled molten salt reactors

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Nuclear Science and Techniques 2022年第8期33卷 16-32页

作者： Xian-Di Zuo Mao-Song Cheng Yu-qing dai Kai-Cheng Yu Zhi-Min dai Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China

In molten salt reactors(MSRs),the liquid fuel salt circulates through the primary loop and a part of the delayed neutron precursors(DNPs)decays outside the reactor *** model and analyze the flow field effect of DNPs in channel-type liquid-fueled MSRs,a three-dimensional space-time dynamics code,named ThorCORE3D,that couples neutronics,core thermalhydraulics,and a molten salt loop system was developed and validated with the Molten Salt Reactor Experiment(MSRE)*** effects of external loop recirculation time,fuel flow rate,and core flow field distribution on the delayed neutron fraction loss of MSRE at steadystate were modeled and simulated using the ThorCORE3D ***,the flow field effect of the DNPs on the system responses of the MSRE in the reactivity insertion transient under different initial conditions was analyzed systematically for the channel-type liquid-fueled *** results indicate that the flow field condition has a significant effect on the steady-state delayed neutron fractions and will further affect the transient power and temperature responses of the reactor *** analysis results for the effect of the DNP flow field can provide important references for the design optimization and safety analysis of liquid-fueled MSRs.

关键词： Molten salt reactor Delayed neutron precursor Nodal expansion method Coupled neutronics and thermal-hydraulics

CHARACTERISTICS OF CORRELATION AND SPECTRUM BETWEEN WALL FLUCTUATING PRESSURE AND FLUCTUATING VELOCITY OF IMPINGING JET

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Journal of Hydrodynamics 2002年第3期14卷 21-28页

作者： dai, Guang-qing Yang, Yong-Quan Yang, qing Wang, Hai-Yun Hydraulics Lab. of High Speed Flows Sichuan Univ. Chengdu 610065 China

The correlation, between wall fluctuating pressure and fluctuating velocity, on the bed of plunging pool under the action of single and twin impinging jet, and their spectrum and turbulent scale are investigated in the paper by using 2-D LDA and the dynamic pressure scanning system of multiple points. It is found that the cross correlation between the horizontal fluctuating velocity and the fluctuating pressure of twin jet is bigger than that of single jet, and the spectrums of horizontal fluctuating velocity and fluctuating pressure obviously have approximately same dominant frequency. The relationship between the fluctuation pressure coefficient on wall and the turbulent intensity near the wall can be described with logarithmic curve.

关键词： Hydraulic structures Pressure Pressure measurement Turbulence Velocity

Carbon dioxide adsorption behaviors of aluminum-pillared montmorillonite-supported alkaline earth metals

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Journal of Environmental Sciences 2020年第12期32卷 109-117页

作者： Kai Wu qing Ye Runping Wu Sha Chen Hongxing dai Key Laboratory of Beijing on Regional Air Pollution Control Department of Environmental ScienceCollege of Environmental and Energy EngineeringBeijing University of TechnologyBeijing 100124China Beijing Key Laboratory for Green Catalysis and Separation Key Laboratory of Beijing on Regional Air Pollution ControlKey Laboratory of Advanced Functional MaterialsEducation Ministry of Chinaand Laboratory of Catalysis Chemistry and NanoscienceDepartment of Chemistry and Chemical EngineeringCollege of Environmental and Energy EngineeringBeijing University of TechnologyBeijing 100124China

The Al-pillared montmorillonite-supported alkaline earth metal 5M/Al-PILC(PILC = pillared clay, M = Mg, Ca, Sr, and Ba) and x Mg/Al-PILC( x = 1, 3, 5, and 7 wt.%) samples were prepared using an impregnation method. Physical properties of the materials were determined by means of X-ray diffraction(XRD) and N2 adsorption-desorption, and their CO2 adsorption behaviors were investigated using the thermogravimetric analyzer(TG), CO2 temperatureprogrammed desorption(CO2-TPD), and in situ diffuse reflectance infrared transform spectroscopy(in situ-DRIFTS) techniques. It is shown that 5 Mg/Al-PILC possessed the highest CO2 adsorption capacity(2.559 mmol/g). The characterization results indicate that Alpillaring increased the specific surface area of montmorillonite, which was beneficial for the adsorption of CO2. The CO2 adsorption process on the sample was mainly chemical adsorption, and alkalinity was the main factor influencing its adsorption capacity. The alkalinity of the sample was enhanced by loading an appropriate amount of alkaline earth metal, and the adsorbed CO2 was present in the form of bicarbonate and carbonate. In addition, the 5Mg/Al-PILC sample exhibited an excellent regeneration efficiency. We believe that the outcome of this research would provide a good option for developing highly effective CO2 adsorption materials.

关键词： Montmorillonite Al-pillaring Adsorbent CO2 adsorption Alkaline earth metal

Promotional effect of cobalt doping on catalytic performance of cryptomelane-type manganese oxide in toluene oxidation

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Journal of Environmental Sciences 2023年第4期126卷 263-274页

作者： Ning Dong Mengyue Chen qing Ye Dan Zhang Hongxing dai Key Laboratory of Beijing on Regional Air Pollution Control Department of Environmental ScienceSchool of Environmental and Chemical EngineeringFaculty of Environment and LifeBeijing University of TechnologyBeijing 100124China R&D Department of Atmospheric Prevention and Control Technology Guangdong Suncere Technology Co.Ltd.Guangzhou 510220China Beijing Key Laboratory for Green Catalysis and Separation Key Laboratory of Beijing on Regional Air Pollution ControlKey Laboratory of Advanced Functional MaterialsEducation Ministry of Chinaand Laboratory of Catalysis Chemistry and NanoscienceDepartment of Environmental Chemical EngineeringSchool of Environmental and Chemical EngineeringFaculty of Environment and LifeBeijing University of TechnologyBeijing 100124China

The cryptomelane-type manganese oxide (OMS-2)-supported Co (x Co/OMS-2;x=5,10,and15 wt.%) catalysts were prepared via a pre-incorporation *** as-prepared materials were used as catalysts for catalytic oxidation of toluene (2000 ppmV).Physical and chemical properties of the catalysts were measured using the X-ray diffraction (XRD),Fourier transform infrared spectroscopic (FT-IR),scanning electron microscopic (SEM),X-ray photoelectron spectroscopy (XPS),and hydrogen temperature-programmed reduction (H_(2)-TPR)*** all of the catalysts,10Co/OMS-2 performed the best,with the T90%,specific reaction rate at 245℃,and turnover frequency at 245℃ (TOFCo) being 245℃,1.23×10^(-3)moltoluene/(gcat·sec),and 11.58×10^(-3)sec-1for toluene oxidation at a space velocity of 60,000mL/(g·hr),*** excellent catalytic performance of 10Co/OMS-2 were due to more oxygen vacancies,enhanced redox ability and oxygen mobility,and strong synergistic effect between Co species and OMS-2 ***,in the presence of poisoning gases CO_(2),SO_(2)or NH_(3),the activity of 10Co/OMS-2 decreased for the carbonate,sulfate and ammonia species covered the active sites and oxygen vacancies,*** the activation treatment,the catalytic activity was partly *** good low-temperature reducibility of 10Co/OMS-2 could also facilitate the redox process accompanied by the consecutive electron transfer between the adsorbed O_(2)and the cobalt or manganese *** the oxidation process of toluene,the benzoic and aldehydic intermediates werefirst generated,which were further oxidized to the benzoate intermediate that were eventually converted into H_(2)O and CO_(2).

关键词： Cryptomelane-type manganese oxide Cobalt doping Volatile organic compound Toluene oxidation

An investigation on catalytic performance and reaction mechanisms of Fe/OMS-2 for the oxidation of carbon monoxide, ethyl acetate, and toluene

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Journal of Environmental Sciences 2022年第2期34卷 258-268页

作者： Ning Dong Mengyue Chen qing Ye Dan Zhang Hongxing dai Key Laboratory of Beijing on Regional Air Pollution Control Department of Environmental ScienceSchool of Environmental and Chemical EngineeringFaculty of Environment and LifeBeijing University of TechnologyBeijing 100124China Beijing Key Laboratory for Green Catalysis and Separation Key Laboratory of Beijing on Regional Air Pollution ControlKey Laboratory of Advanced Functional MaterialsEducation Ministry of Chinaand Laboratory of Catalysis Chemistry and NanoscienceDepartment of Environmental Chemical EngineeringSchool of Environmental and Chemical EngineeringFaculty of Environment and LifeBeijing University of TechnologyBeijing 100124China

The octahedral molecular sieve(OMS-2)-supported Fe( xFe/OMS-2: x = 1, 3, 5, and 10) catalysts were prepared using the pre-incorporation method. Physicochemical properties of the as-synthesized materials were characterized by means of various techniques, and their catalytic activities for CO, ethyl acetate, and toluene oxidation were evaluated. Among all of the samples, performed the best, with the reaction temperature required to achieve 90% conversion( T 90%) being 160 ℃ for CO oxidation, 210 ℃ for ethyl acetate oxidation, and 285 ℃ for toluene oxidation. Such a good catalytic performance of 5Fe/OMS-2 was associated with its high(Mn^(3+) + Mn^(2+)) content and adsorbed oxygen species concentration, and good lowtemperature reducibility and lattice oxygen mobility as well as strong interaction between Fe and OMS-2. In addition, catalytic mechanisms of the oxidation of three pollutants over the 5Fe/OMS-2 catalyst were also studied. It was found that CO, ethyl acetate or toluene was first adsorbed, then the related intermediates were formed, and finally the formed intermediates were completely converted into CO_(2) and H_(2)O.

关键词： Cryptomelane-type OMS-2 Supported iron catalyst CO oxidation Volatile organic compound oxidation Toluene oxidation

Designing Rules of Laser-Clad High-Entropy Alloy Coatings with Simple Solid Solution Phases

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Acta Metallurgica Sinica(English Letters) 2020年第8期33卷 1064-1076页

作者： Yongfei Juan Jiao Zhang Yongbing dai qing Dong Yanfeng Han Shanghai Key Lab of Advanced High-Temperature Materials and Precision Forming Shanghai Jiao Tong UniversityShanghai 200240China

The criteria of process parameters(μ≤4),atomic size difference(ε≤5.8,δ≤11 andα≤2),thermodynamic(-14.5≤△Hmix≤6.5 andΩ≥1.8)in the prediction of the phase stability for laser-clad high-entropy alloy coatings are studied in ***,the criteria of valence electron concentration(VEC)applied to distinguish the stability of different solid solution phases are as follows:VEC<7.65 for simple BCC,VEC≥7.65 for simple face-centered cubic(FCC),7.14

关键词： High-entropy alloys Laser cladding Phase stability Criteria

A high strength pH responsive supramolecular copolymer hydrogel

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Science China(Technological Sciences) 2017年第1期60卷 78-83页

作者： WANG qing ZHANG YinYu dai XiYang SHI XiaoHuan LIU WenGuang School of Materials Science and Engineering Tianjin Key Laboratory of Composite and Functional Materials Tianjin University Tianjin 300354 China

Constructing high strength pH sensitive supramolecular polymer hydrogel remains very challenging due to the unavoidable network swelling caused by ionization of acid or basic groups at a specified *** this work,we proposed a simple and very convenient approach to fabricate high strength pH responsive supramolecular polymer(SP) hydrogels by one-pot copolymerization of N-acryloyl glycinamide(NAGA) and 2-vinyl-4,6-diamino-1,3,5-triazine(VDT),two feature hydrogen bonding *** these PNAGA-PVDT SP hydrogels obtained,the hydrogen bonding of NAGA was shown to play a dominant role in reinforcing strength,while the hydrogen bonding of diaminotriazine served as a pH sensitive *** pH 3,the mechanical properties of PNAGA-PVDT hydrogels decreased to a different extent due to the breakup of hydrogen bonding;in contrast,the hydrogel resumed the original strength while pH was raised to 7.4 because of reconstruction of hydrogen *** the selected pH range,the PNAGA-PVDT hydrogels exhibited up to 1.25 MPa tensile strength,845% breaking strain,69 kPa Young's modulus and 21 MPa compressive *** novel high strength pH-responsive SP hydrogels may find applications in biomedical and industrial fields.

关键词： high strength pH responsive supramolecular polymer hydrogel

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不同开槽结构对气膜冷却效果的影响研究

汽轮机技术 2025年第1期67卷 42-48页

作者：王旭戴萍王少卿周永洋季天宇青岛科技大学机电工程学院青岛266061

研究了不同吹风比下圆形孔、横向槽、圆弧槽以及阶梯槽气膜孔的气膜冷却效率,对相同槽宽、槽深情况下不同开槽结构的作用效果进行研究。结果表明,横向槽能够使下游产生反肾形涡对抑制了肾形涡对的不利影响,中低吹风比下其冷却优势最为... 详细信息

研究了不同吹风比下圆形孔、横向槽、圆弧槽以及阶梯槽气膜孔的气膜冷却效率,对相同槽宽、槽深情况下不同开槽结构的作用效果进行研究。结果表明,横向槽能够使下游产生反肾形涡对抑制了肾形涡对的不利影响,中低吹风比下其冷却优势最为明显。圆弧槽在射流经过其下游槽壁的圆弧结构时,会发生科恩达效应产生一个高效冷却区域,提高了气膜贴壁性。阶梯槽通过阶梯结构促使射流在下游槽壁产生了2个二次流,进而提高了气膜展向上的流动,增大了气膜覆盖面积。

关键词：气膜冷却横向槽吹风比数值计算