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RF design optimization for the SHINE 3.9 GHz cavity

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Nuclear Science and Techniques 2020年第7期31卷 97-105页

作者： yu-xin Zhang Jin-Fang Chen Dong Wang Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201204China ShanghaiTech University Shanghai 201210China Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201204China

The Shanghai high-repetition-rate XFEL and extreme light facility(SHINE)under construction is designed to be one of the most advanced free electron laser(FEL)facilities in the *** main part of the SHINE facility is an 8 GeV superconducting Linac operating in continuous wave(CW)*** Linac consists of seventy-five 1.3 GHz and two 3.9 GHz *** on the design and experience of 3.9 GHz cavities in the European X-ray free electron laser(E-XFEL)and the Linac coherent light source-II(LCLS-II)projects,we optimize the SHINE 3.9 GHz cavity design to adapt it for CW mode *** this paper,we present a particular redesign of the end group for the SHINE 3.9 GHz superconducting cavity that includes a redesign of the end cell and beam pipe to shift away the potentially troublesome lowest highorder modes(HOMs),a modification of the main coupler antenna,and a tuning of the HOM notch filter to meet the cavity *** losses calculations on the HOM coupler antennas show that the overheating on the inner conductor at the operating mode is diminished ***,we have also studied the HOMs to ensure there are no dangerously trapped modes in the optimized cavity design.

关键词： cavity antenna tuning

Response Solutions for Degenerate Reversible Harmonic Oscillators with Zero-average Perturbation

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Acta Mathematica Sinica,English Series 2023年第10期39卷 2006-2030页

作者： xin yu GUAN Jian Guo SI Wen SI School of Statistics and Mathematics Shandong University of Finance and EconomicsJi’nan 250002P.R.China School of Mathematics Shandong UniversityJi’nan 250100P.R.China

In this paper,we consider a class of normally degenerate quasi-periodically forced reversible systems,obtained as perturbations of a set of harmonic oscillators,{x˙=y+∈f1(ωt,x,y),y˙=λx^(l)+∈f2(ωt,x,y),where 0≠λ∈R,l>1 is an integer and the corresponding involution G is(−θ,x,−y)→(θ,x,y).The existence of response solutions of the above reversible systems has already been proved in[22]if[f2(ωt,0,0)]satisfies some non-zero average conditions(See the condition(H)in[22]),here[·]denotes the average of a continuous function on T^(d).However,discussing the existence of response solutions for the above systems encounters difficulties when[f_(2)(ωt,0,0)]=0,due to a degenerate implicit function must be *** article will be doing work in this *** purpose of this paper is to consider the case where[f2(ωt,0,0)]=*** precisely,with 2p˜0(seeλ˜in(2.2))and sufficiently small,response solutions exist for eachωsatisfying a weak non-resonant condition;(2)Forλ0 and l−p is even,we prove the system admits no response solutions in most regions.

关键词： Degenerate harmonic oscillators zero-average perturbation KAM theory reversible system response solutions

Molecular test shows the color pattern is not so reliable in diagnostic of genus Dysphaea Selys(Odonata:Euphaeidae)

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Zoological Systematics 2019年第2期44卷 91-99页

作者： Yao Ji xin yu Institute of Entomology College of Life Sciences Nankai University College of Life Sciences Chongqing Normal University

A molecular study based on COI, 16S and 28S genes reveals that a batch of specimens(7 males and 4 females) of Dysphaea Selys, 1853 collected from central Vietnam,which include different color patterns of wings and body, and were originally identified as three different species, are all the same species. This study implies that, in some group of Odonata,identification only depending on color pattern may be unreliable, no matter what huge variations there are.

关键词： Odonata dragonfly wing color pattern variation molecular phylogeny

Experimental study on dynamic mechanical property of cemented tailings backfill under SHPB impact loading

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International Journal of Minerals,Metallurgy and Materials 2019年第4期26卷 404-416页

作者： yu-ye Tan xin yu Davide Elmo Lin-hui Xu Wei-dong Song Key Laboratory of High-Efficient Mining and Safety of Metal Mines (Ministry of Education of China) University of Science and Technology Beijing School of Civil and Resources Engineering University of Science and Technology Beijing Norman B.Keevil Institute of Mining Engineering Applied Science SchoolUniversity of British Columbia

Cemented tailings backfill(CTB) have increasingly been used in recent years to improve the stability of mining stopes in deep underground mines. Deep mining processes are often associated with rock bursting and high-speed dynamic loading conditions. Therefore, it is important to investigate the characteristics and dynamic mechanical behavior of CTB. This paper presents the results of dynamic tests on CTB specimens with different cement and solid contents using a split Hopkinson pressure bar(SHPB). The results showed that some CTB specimens exhibited one to two lower stress peaks after reaching dynamic peak stress before they completely failed. The greater the cement-to-tailings ratio is, the more obvious the strain reaction. This property mainly manifested as follows. First,the dynamic peak stress increased with the increase of the cement-to-tailings ratio when the impact velocity was fixed. Second, the dynamic peak stress had a quadratic relationship with the average stress rate. Third, the cement-to-tailings ratio could enhance the increase rate of dynamic peak stress with strain rate. In addition, the dynamic strength enhancement factor K increased with the increase of strain rate, and its value was larger than that of the rock samples. The failure modes of CTB specimens under low-speed impact were tensile failure and X conjugate shear failure, where were nearly the same as those under static uniaxial and triaxial compression. The CTB specimens were crushed and broken under critical strain, a failure mode similar to that of low-strength concrete. The results of the experimental research can improve the understanding of the dynamic mechanical properties of CTB and guide the strength design of deep mining backfills.

关键词： impact loading test cemented tailings backfill dynamic mechanical properties split Hopkinson pressure bar

High-Performanceα-Diimine Nickel Complexes for Facile Access of PE Elastomers with Exceptional Material Properties

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Chinese Journal of Polymer Science 2024年第5期42卷 620-635,I0008页

作者： Li-Dong Qin xin-yu Wang Qaiser Mahmood Zhi-xin yu Yi-Zhou Wang Song Zou Tong-Ling Liang Wen-Hua Sun School of Pharmaceutical Sciences Changchun University of Chinese MedicineChangchun130117China Chemistry and Chemical Engineering Guangdong Laboratory Shantou515031China Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science Institute of ChemistryChinese Academy of SciencesBeijing100190China

For practicable elastomeric polyethylene,achieving high catalyst thermal stability and activity,along with precise control of polymer properties such as branching density,molecular weights,and distribution,is crucial but *** this study,two sets of symmetricalα-diimine nickel complexes,each comprising four nickel bromide or chloride complexes,were synthesized and investigated their performance for ethylene polymerization under various reaction *** activation with either Et2AlCl or MMAO cocatalysts,these complexes displayed not only high activity but also generated high molecular weight polyethylenes with controlled polydispersity and a substantial number of *** catalyst with the least steric hindrance displayed the remarkable high activity(up to 1.2×10^(7) g·mol^(-1)·h^(-1)).Notably,nickel bromides demonstrated higher activity compared to their chloride *** investigation into the effect of reaction temperature on catalytic performance revealed that NiBrMe-MMAO system displayed high thermal stability(activity up to 2.51×10^(6) g·mol^(-1)·h^(-1) at 100℃)and consistently yielded high polymer molecular weights with narrow polydispersity over a broad temperature range of 30-100℃.Of significant note,mechanical analysis of the resulting polyethylene demonstrated excellent ultimate tensile strength and high strain at ***,the polyethylene sample prepared at 100℃exhibited ultimate tensile strength up to 10 MPa with 1863%maximum strain at break and a strain recovery of up to 54.9%after ten cycles at a fixed strain of 300%,indicating excellent material properties of prepared thermoplastic polyethylene elastomers(TPE).

关键词： Thermoplastic polyethylene elastomers α-Diimine nickel pre-catalysts Ethylene polymerization Mechanical properties Highly branched polyethylene

Numerical investigations of the interactions between bubble induced shock waves and particle based on OpenFOAM

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Journal of Hydrodynamics 2024年第2期36卷 355-362页

作者： Jia-xin yu Jin-sen Hu yu-hang Liu Yi-fan Liu Dan Gao yu-ning Zhang Key Laboratory of Power Station Energy Transfer Conversion and System Ministry of EducationSchool of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China

The presence of particles and the shock waves generated by the cavitation bubbles can significantly affect the safety and the performance of hydrodynamic *** the present paper,the shock waves generated by cavitation bubble collapsing near the particle are numerically investigated based on the OpenFOAM together with the numerical schlieren for the shock wave *** numerical results reveal that the stand-off distance is one of the paramount factors affecting the interactions between the particle and the shock *** different kinds of shock waves(e.g.,bubble-inception,jet formation,particle reflected and jet-split shock waves)are observed during the bubble collapsing near the *** stand-off distance smaller than 0.5 or larger than 1.1,the maximum pressure at particle surface generated by the bubble growth can surpass those of the collapse stage.

关键词： Particle-bubble interaction shockwaves jetdynamics

Theoretical analysis and experimental validation of radial cascaded composite ultrasonic transducer

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Chinese Physics B 2021年第4期30卷 184-192页

作者： Xiao-yu Wang Zhi-xin yu Jing Hu Shu-yu Lin Shaanxi Key Laboratory of Ultrasonics Institute of Applied AcousticsShaanxi Normal UniversityXi'an 710119China

A radial cascaded composite ultrasonic transducer is *** transducer consists of three short metal tubes and two radially polarized piezoelectric ceramic short tubes arranged alternately along the radial *** short metal tubes and the piezoelectric ceramic short tubes are connected in parallel electrically and in series mechanically,which can multiply the input sound power and sound *** on the theory of plane stress,the electro-mechanical equivalent circuit of radial vibration of the transducer is derived *** resonance/anti-resonance frequency equation and the expression of the effective electromechanical coupling coefficient are *** electromechanical characteristics are determined by changing the radial geometric *** prototypes of the transducers are designed and manufactured to support the analytical *** is concluded that the theoretical resonance/anti-resonance frequencies are consistent with the numerical and experimental *** R_(2) is at certain values,both the anti-resonance frequency and effective electromechanical coupling coefficient corresponding to the second mode have maximal *** radial cascaded composite ultrasonic transducer is expected to be used in the fields of ultrasonic water treatment and underwater acoustics.

关键词： radial cascaded transducer radial vibration equivalent circuit effective electromechanical coupling coefficient

Perforation of levonorgestrel-releasing intrauterine system found at one month after insertion:A case report

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World Journal of Clinical Cases 2023年第1期11卷 172-176页

作者： Guo-Rui Zhang xin yu Department of Obstetrics and Gynecology State Key Laboratory of ComplexSevere and Rare DiseasesNational Clinical Research Center for Obstetric&Gynecologic DiseasesPeking Union Medical College HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100730China

BACKGROUND The levonorgestrel-releasing intrauterine system(LNG-IUS)is widely used in contraception,menorrhagia,dysmenorrhea and to prevent endometrial hyperplasia during estrogen *** is more often seen after early postpartum *** of the LNG-IUS occurring one month after placement is *** SUMMARY A 42-year-old female complained of progressive dysmenorrhea and increased menstrual *** was diagnosed with adenomyosis and the LNG-IUS was inserted in her uterine *** ultrasound examination one month later revealed that the intra-uterine device(IUD)was not found in the uterine cavity,and further X-ray and pelvic magnetic resonance imaging showed an abnormal signal area in the left posterior region of the *** exploratory surgery was performed and the LNG-IUS was found in the left uterosacral *** Perforation of a LNG-IUS occurring one month after placement is rare,and is more common in inexperienced operators and after early postpartum *** the operation is difficult,ultrasound monitoring is recommended to reduce the risk of IUD *** patients with inadequate surgery,postoperative imaging is recommended to detect potential risks as soon as possible.

关键词： Levonorgestrel-releasing intrauterine system Perforation Malposition Case report

Total Ionizing Dose Effect and Failure Mechanism of Digital Signal Processor

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Chinese Journal of Electronics 2021年第5期30卷 986-990页

作者： yu xin LU Wu LI Xiaolong LIU Mohan WANG xin SUN Jing GUO Qi xinjiang Technical Institute of Physics and Chemistry Laboratory of Solid State Radiation Physics

Ionizing radiation effect and failure mechanism of Digital signal processor(DSP) is studied through test-board and automatic test equipment to find the relationship between system function failure and parameter degradation. Static bias is more sensitive than dynamic bias when DSP is tested on-line during radiation. Core current, high-Z leakage current and timing parameter are sensitive to ionizing radiation. No enhanced low-dose-rate sensitivity is found by comparing experiment results under high and low dose rate *** memory interface and Timer are deduced to be the sensitive module by step radiation and analysis basing full parameter test in Verigy 93000. The timing parameter degradation have a strong correlation to these module functions. And the degeneration mechanism is analysed on inverter through Hspice simulation which indicate the leakage circuit caused by radiation can lead a delay to the digital signal propagating. The parasitical capacitance among long connections make it worse to the data transmission around DSP, field programmable gate array and memory. Then an early function failure occurs in test board than Verigy 93000. This work provide support to systematic radiation hardness design and hardness assurance/lot acceptance testing in space applications.

关键词： Verigy 93000 analysis basing full parameter test digital signal propagating radiation effect radiation effects DSP external memory interface leakage currents early function failure leakage circuit test board sensitive module system function failure high dose rate radiation static bias automatic test equipment timing parameter degradation low dose rate radiation field programmable gate array enhanced low-dose-rate sensitivity Digital signal processor degeneration mechanism systematic radiation hardness design radiation hardening (electronics) field programmable gate arrays integrated circuit testing ionizing radiation dynamic bias module functions step radiation digital signal processing chips failure mechanism test-board