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A non-invasive diagnostic method of cavity detuning based on a convolutional neural network

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Nuclear Science and Techniques 2022年第7期33卷 25-35页

作者： liu-yuan zhou Hao Zha Jia-Ru Shi Jia-Qi Qiu Chuan-Jing Wang Yun-Sheng Han Huai-Bi Chen Department of Engineering Physics Tsinghua UniversityBeijing100084China Key Laboratory of Particle and Radiation Imaging Tsinghua UniversityBeijing100084China

As modern accelerator technologies advance toward more compact sizes,conventional invasive diagnostic methods of cavity detuning introduce negligible interference in measurements and run the risk of harming structural surfaces.To overcome these difficulties,this study developed a non-invasive diagnostic method using knowledge of scattering parameters with a convolutional neural network and the interior point method.Meticulous construction and training of the neural network led to remarkable results on three typical acceleration structures:a 13-cell S-band standing-wave linac,a 12-cell X-band traveling-wave linac,and a 3-cell X-band RF gun.The trained networks significantly reduced the burden of the tuning process,freed researchers from tedious tuning tasks,and provided a new perspective for the tuning of side-coupling,semi-enclosed,and total-enclosed structures.

关键词： Cavity detuning Convolutional neural network Equivalent circuit

Design, fabrication, and testing of low-group-velocity S-band traveling-wave accelerating structure

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Nuclear Science and Techniques 2022年第11期33卷 133-143页

作者： Xian-Cai Lin Hao Zha Jia-Ru Shi liu-yuan zhou Yi-Fan Liang Jian Gao Qiang Gao Huai-Bi Chen Chuan-Xiang Tang Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Particle and Radiation Imaging(Tsinghua University) Ministry of EducationBeijing 100084China

To implement the Tsinghua Thomson Scattering X-ray Source upgrade plan and the Very Compact Inverse Compton Scattering Gamma-ray Source (VIGAS) program, a new 1.5-m traveling-wave accelerating structure was designed to replace the old 3-m SLAC-type structure with the aim of increasing the accelerating gradient from15 to 30 MV/m. The new type of structure works in the 3π/4 mode with a comparatively low group velocity varying from 0.007c to 0.003c to increase the accelerating gradient at a given power. An elliptical iris was employed to reduce the surface field enhancement. The filling process of the low-group-velocity structure was analyzed using a circuit model. After fabrication, the structure was precisely tuned using the non-contact tuning method, followed by detailed low-power radiofrequency measurements. The structure was first installed and utilized at a beamline for the terahertz experiment at Tsinghua University. After 120 h of conditioning, it is now operating at a gradient of 24.2 MV/m and a 20.7-MW input power, with the klystron operating at its full power. It is expected to generate an accelerating gradient of 30 MV/m when the klystron power is upgraded to 30 MW in the near future.

关键词： Traveling-wave accelerating structure Cavity optimization Tuning method High-power test

Development of a seven-cell S-band standing-wave RF-deflecting cavity for Tsinghua Thomson scattering X-ray source

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Nuclear Science and Techniques 2021年第4期32卷 20-29页

作者： Xian-Cai Lin Hao Zha Jia-Ru Shi liu-yuan zhou Shuang liu Jian Gao Huai-Bi Chen Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Particle and Radiation Imaging(Tsinghua University) Ministry of EducationBeijing 100084China

A 2856-MHz,π-mode,seven-cell standingwave deflecting cavity was designed and fabricated for bunch length measurement in Tsinghua Thomson scattering X-ray source(TTX)facility.This cavity was installed in the TTX and provided a deflecting voltage of 4.2 MV with an input power of 2.5 MW.Bunch length diagnoses of electron beams with energies up to 39 MeV have been performed.In this article,the RF design of the cavity using HFSS,fabrication,and RF test processes are reviewed.High-power operation with accelerated beams and calibration of the deflecting voltage are also presented.

关键词： Deflecting RF cavity Standing wave Bunchlength measurement Thomson X-ray source

Development and high-gradient test of a two-half accelerator structure

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Nuclear Science and Techniques 2021年第6期32卷 54-62页

作者： Mao-Mao Peng Jia-Ru Shi Hao Zha Xian-Cai Lin Ze-Ning liu Yu-Liang Jiang Jian Gao liu-yuan zhou Fo-Cheng liu Xiang-Cong Meng Huai-Bi Chen Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Particle and Radiation Imaging Tsinghua UniversityMinistry of EducationBeijing 100084China

This paper reports on the design,fabrication,RF measurement,and high-power test of a prototype accelerator—such as 11.424 GHz with 12 cells—and a traveling wave of two halves.It was found that the unloaded gradient reached 103 MV/m during the high-power test and the measured breakdown rate,after 3.17×10^(7) pulses,was 1.62×10^(-4)/pulse/m at 94 MV/m and a 90 ns pulse length.We thus concluded that the high-gradient two-half linear accelerator is cost-effective,especially in high-frequency RF linear acceleration.Finally,we suggest that silverbased alloy brazing can further reduce costs.

关键词： Two-half structure Silver-based alloy brazing Low cost High gradient

Mass transfer characteristics of chiral pharmaceuticals on membrane used for polar organic chemical integrative sampler

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Journal of Environmental Sciences 2024年第2期136卷 670-681页

作者： Liyang Wang Ruixia liu Youya zhou Peng yuan Xiaoling liu Hongjie Gao College of Water Science Beijing Normal UniversityBeijing 100018China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental ScienceBeijing 100012China Technical Centre for Soil Agriculture and Rural Ecology and EnvironmentMinistry of Ecology and EnvironmentBeijing 100012China

Passive sampling technology has good application prospects for monitoring trace pollutants in aquatic environments.Further research on the sampling mechanism of this technology is essential to improve the measurement accuracy and extend the application scope of this approach.In this study,adsorption and permeation experiments were performed to investigate the sorption and mass transfer properties of five chiral pharmaceuticals at the enantiomeric level on polyethersulfone(PES)and polytetrafluoroethylene(PTFE)membranes used in a polar organic chemical integrative sampler.Batch adsorption experiments showed that the PES membrane had an adsorption phenomenon for most selected pollutants and an insignificant sorption behavior was observed for all selected pharmaceuticals on the PTFE membrane except for R(S)-fluoxetine.The diffusion coefficients of selected pharmaceuticals onto the PTFE membrane were approximately one order of magnitude higher than those onto the PES membrane.The permeation experiment indicated that under different hydraulic conditions,the change of the relative pollutant concentration through the PTFE membrane for the composite pollutant system was more obvious than that for the single pollutant system,and mass transfer hysteresis exists for both contaminant systems through PES membranes.Using the first-order equation or 3-component model to estimate the overall mass transfer coefficients,the results showed that the overall mass transfer coefficient values of pollutants in the composite pollutant system onto both membranes were higher than those in the single pollutant system.This parameter was mainly influenced by the synergistic effects of the multi-analyte interaction and diminished water boundary layers during the mass transfer process.

关键词： Sorption phenomenon Permeation behavior Mass transfer properties Modeling calculation Chiral pharmaceuticals PES and PTFE membrane

Cellular strategies to induce immune tolerance after liver transplantation:Clinical perspectives

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World Journal of Gastroenterology 2024年第13期30卷 1791-1800页

作者： Ai-Wei zhou Jing Jin yuan liu Department of Liver Surgery Renji Hospital Affiliated to Shanghai Jiao Tong University School of MedicineShanghai 200127China Department of Nursing Renji Hospital Affiliated to Shanghai Jiao Tong University School of MedicineShanghai 200127China Department of Liver Transplantation Shanghai Immune Therapy InstituteShanghai 200127China

Liver transplantation(LT)has become the most efficient treatment for pediatric and adult end-stage liver disease and the survival time after transplantation is becoming longer due to the development of surgical techniques and perioperative management.However,long-term side-effects of immunosuppressants,like infection,metabolic disorders and malignant tumor are gaining more attention.Immune tolerance is the status in which LT recipients no longer need to take any immunosuppressants,but the liver function and intrahepatic histology maintain normal.The approaches to achieve immune tolerance after transplantation include spontaneous,operational and induced tolerance.The first two means require no specific intervention but withdrawing immunosuppressant gradually during follow-up.No clinical factors or biomarkers so far could accurately predict who are suitable for immunosuppressant withdraw after transplantation.With the understanding to the underlying mechanisms of immune tolerance,many strategies have been developed to induce tolerance in LT recipients.Cellular strategy is one of the most promising methods for immune tolerance induction,including chimerism induced by hematopoietic stem cells and adoptive transfer of regulatory immune cells.The safety and efficacy of various cell products have been evaluated by prospective preclinical and clinical trials,while obstacles still exist before translating into clinical practice.Here,we will summarize the latest perspectives and concerns on the clinical application of cellular strategies in LT recipients.

关键词： Cellular therapy Induced tolerance Liver transplantation Regulatory T cells Regulatory dendritic cells

Relationship among Parkinson’s disease, constipation, microbes, and microbiological therapy

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World Journal of Gastroenterology 2024年第3期30卷 225-237页

作者： Xin-Yang yuan Yu-Sen Chen zhou liu Department of Neurology Affiliated Hospital of Guangdong Medical UniversityZhanjiang 524000Guangdong ProvinceChina Institute of Neurology Guangdong Key Laboratory of Age-Related Cardiac and Cerebral DiseasesZhanjiang 524000Guangdong ProvinceChina

This comprehensive review elucidates the complex interplay between gut microbiota and constipation in Parkinson’s disease(PD),a prevalent non-motor symptom contributing significantly to patients’morbidity.A marked alteration in the gut microbiota,predominantly an increase in the abundance of Proteobacteria and Bacteroidetes,is observed in PD-related constipation.Conventional treatments,although safe,have failed to effectively alleviate symptoms,thereby necessitating the development of novel therapeutic strategies.Microbiological interventions such as prebiotics,probiotics,and fecal microbiota transplantation(FMT)hold therapeutic potential.While prebiotics improve bowel movements,probiotics are effective in enhancing stool consistency and alleviating abdominal discomfort.FMT shows potential for significantly alleviating constipation symptoms by restoring gut microbiota balance in patients with PD.Despite promising developments,the causal relationship between changes in gut microbiota and PD-related constipation remains elusive,highlighting the need for further research in this expanding field.

关键词： Parkinson disease Constipation Gut microbiota Prebiotics Probiotics Fecal microbiota transplantation

Engineering vascularized organotypic tissues via module assembly

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International Journal of Extreme Manufacturing 2024年第1期6卷 155-175页

作者： Zhenzhen zhou Changru liu Yuting Guo yuan Pang Wei Sun Biomanufacturing Center Department of Mechanical EngineeringTsinghua UniversityHaidian DistrictBeijing 100084People’s Republic of China Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Beijing 100084People’s Republic of China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationBeijing 100084People’s Republic of China Department of Mechanical Engineering Drexel UniversityPhiladelphiaPA 19104United States of America

Adequate vascularization is a critical determinant for the successful construction and clinical implementation of complex organotypic tissue models. Currently, low cell and vessel density and insufficient vascular maturation make vascularized organotypic tissue construction difficult,greatly limiting its use in tissue engineering and regenerative medicine. To address these limitations, recent studies have adopted pre-vascularized microtissue assembly for the rapid generation of functional tissue analogs with dense vascular networks and high cell density. In this article, we summarize the development of module assembly-based vascularized organotypic tissue construction and its application in tissue repair and regeneration, organ-scale tissue biomanufacturing, as well as advanced tissue modeling.

关键词： vascularized organotypic tissue module assembly regenerative medicine tissue engineering

Experimental,Numerical,and Analytical Studies on the Bending of Mechanically Lined Pipe

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China Ocean Engineering 2024年第2期38卷 221-232页

作者： WEI Wen-bin yuan Lin zhou Jia-sheng liu Zheng State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China School of Civil Engineering Tianjin UniversityTianjin 300072China School of Mechanical Engineering Tianjin UniversityTianjin 300072China

Mechanically lined pipe(MLP)is often used for offshore oil and gas transport because of its low cost and corrosion resistance.During installation and operation,the pipe may undergo severe bending deformation,which causes the liner to separate from the outer pipe and buckles,affecting the stability of the whole line.In this paper,the buckling response of MLP subjected to bending is investigated to clarify its bending characteristics by employing both experiments,numerical simulation,as theoretical methods.Two types of MLPs were manufactured with GB 45 carbon steel(SLP)and Al 6061(ALP)used as the outer pipe material,respectively.The hydraulic expansion and bending experiments of small-scale MLPs are conducted.In addition to the ovalized shape of the cross-section for the SLP specimens,the copper liner was found to wrinkle on the compressive side.In contrast,the liner of ALP remains intact without developing any wrinkling and collapse mode.In addition,a dedicated numerical framework and theoretical models were also established.It was found both the manufacturing and bending responses of the MLP can be well reproduced,and the predicted maximum moment and critical curvatures are in good agreement with the experimental results.

关键词： lined pipe bending nonlinear ring theory buckling plasticity