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Design of large aperture 500 MHz 5-cell superconducting cavity

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Nuclear Science and Techniques 2012年第5期23卷 257-260页

作者： WEI Yelong LIU Jianfei hou Hongtao MA Zhenyu MAO Dongqing FENG ziqiang LU Changwang YU Haibo Shanghai Institute of Applied Physics Chinese Academy of Sciences Jiading Campus Shanghai 201800 China University of Chinese Academy of Sciences Beijing 100049 China Shanghai Key Laboratory of Cryogenics & Superconducting RF Technology Shanghai 201800 China

With the potential application of Energy Recovery Linac (ERL), the superconducting (SC) cavities were developed to deliver much higher current than before. Nowadays, the current of the international SC accelerator designed has already exceeded 100 mA. This paper presents the design of a new 500 MHz 5-cell SC cavity (SINAP 5-cell cavity), in which the parameters r/Q= 515.5 of the fundamental mode and the geometry factor G=275.8 are under an acceptable Radio Frequency (RF) field level (B peak /E acc =4.31 mT/MV/m and E peak /E acc =2.48). This design employs a larger beam pipe to propagate the Higher Order Modes (HOMs) out of the cavity and increases the damping efficiently for the dangerous HOMs. By simulation technique, it has been found that almost all the dangerous HOMs (including TE 111 , TM 110 , and TM 011 ) can be propagated into the beam pipe and are absorbed by ferrite absorbers, when the beam pile is enlarged. Finally, the loss factor for the new 5-cell cavity is also calculated.

关键词：超导腔设计直线加速器光圈无线电频率能量回收几何因子模拟技术

Improving the band alignment at PtSe_(2)grain boundaries with selective adsorption of TCNQ

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Nano Research 2023年第2期16卷 3358-3363页

作者： Yanhui hou ziqiang Xu Yan Shao Linlu Wu Zhongliu Liu Genyu Hu Wei Ji Jingsi Qiao Xu Wu Hong-Jun Gao Yeliang Wang MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices School of Integrated Circuits and ElectronicsBeijing Institute of TechnologyBeijing 100081China Institute of Physics Chinese Academy of SciencesBeijing 100190China Department of Physics and Beijing Key Laboratory of Optoelectronic Functional Materials and Micro-nano Devices Renmin University of ChinaBeijing 100872China

Grain boundaries in two-dimensional(2D)semiconductors generally induce distorted band alignment and interfacial charge,which impair their electronic properties for device ***,we report the improvement of band alignment at the grain boundaries of PtSe_(2),a 2D semiconductor,with selective adsorption of a presentative organic acceptor,tetracyanoquinodimethane(TCNQ).TCNQ molecules show selective adsorption at the PtSe_(2)grain boundary with strong interfacial *** adsorption of TCNQ distinctly improves the band alignment at the PtSe_(2)grain *** the charge transfer between the grain boundary and TCNQ,the local charge is inhibited,and the band bending at the grain boundary is suppressed,as revealed by the scanning tunneling microscopy and spectroscopy(STM/S)*** finding provides an effective method for the advancement of the band alignment at the grain boundary by functional molecules,improving the electronic properties of 2D semiconductors for their future applications.

关键词： organic-two-dimensional(2D)heterostructure PtSe_(2) grain boundary band alignment scanning tunneling microscopy(STM)

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团体心理训练在部队心理卫生工作中的应用

卫生职业教育 2024年第21期42卷 157-160页

作者：侯田雅董薇毛晓飞邓文曦李自强张建国海军军医大学上海200433

近年来,团体心理训练在部队心理工作中的应用得到了广泛关注。本文介绍团体心理训练的起源及其在国内外军队中的特点,阐述基层部队开展团体心理训练的理论基础和具体流程,探讨团体心理训练在部队中的新进展,分析团体心理训练在部队心理... 详细信息

近年来,团体心理训练在部队心理工作中的应用得到了广泛关注。本文介绍团体心理训练的起源及其在国内外军队中的特点,阐述基层部队开展团体心理训练的理论基础和具体流程,探讨团体心理训练在部队中的新进展,分析团体心理训练在部队心理卫生工作中应用的问题及对策,以期改善团体心理训练效果,提高官兵心理素质。

关键词：团体心理训练基层部队心理卫生工作

A Design and Implementation of Multicrypt Solution for DVB Receiver

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High Technology Letters 2004年第3期10卷 10-14页

作者：陈君 Sun Peng Zeng Xuewen hou ziqiang Digital Signal Processing Center Institute of Acoustics Chinese Academy of Sciences Beijing 100080 P.R.China

Conditional Access （CA） System is the essential basis of a Pay-TV System to charge the subscribers. This paper first introduces the standards and mechanisms for a Set-Top-Box（STB）to receive programs scrambled by different CA systems. Then, according to DVB multicrypt solution, a design in detail for such a DVB receiver, I.e. STB is presented. Decoder manufacturers provide STBs with the standard DVB common interface and CA system providers provide detachable CA modules to plug into the STBs through Common Interface. This solution allows broadcasters and customers to change CA system without replacing the STB. Such a design has been implemented in a decoder based on LSI SC2000, and is proved to be an open and secure solution for conditional access.

关键词：设计 DVB接收器 CA系统电视系统

Great progress in developing 500 MHz single cell superconducting cavity in China

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Science China(Physics,Mechanics & Astronomy) 2011年第S2期54卷 169-173页

作者： LIU JianFei hou HongTao MAO DongQing FENG ziqiang MA ZhenYu LUO Chen ZHAO ShenJie ZHAO YuBin YU HaiBo YIN Bo ZHANG ZhiGang ZHENG Xiang LI Zheng Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China Graduate University of Chinese Academy of Sciences Beijing 100049China Shanghai Key Laboratory of Cryogenics&Superconducting RF Technology Shanghai 201800China

Superconducting cavities have been adopted in many kinds of accelerator facilities such as synchrotron radiation light source, hard X-ray free electron laser linac, colliders and energy recovery linacs (ERL). The 500 MHz superconducting cavities will be a candidate to be installed in the high current accelerators and high current ERLs for their large beam aperture, low higher order modes impedance and high current threshold value. This paper presents great progress in the whole sequence of developing 500 MHz superconducting cavity in China. It describes the first in-house successful development of 500 MHz single cell superconducting cavity including the deep-drawing of niobium half cells, electron beam wielding of cavity, surface preparations and vertical testing. The highest accelerating gradient of the fabricated cavity #SCD-02 higher than 10 MV/m was obtained while the quality factor was better than 4×108 at 4.2 K, which has reached the world level of the same kind of cavities.

关键词： superconducting cavity deep-drawing electron beam welding surface processing vertical test accelerating performance

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基于电磁干风洞的大柔性结构准模态试验研究

空气动力学学报 2019年第1期37卷 115-120页

作者：侯英昱刘子强中国航天空气动力技术研究院北京100074

结构的频率是结构的重要动力学特性,对于飞行器来说,当机翼等大型结构在非定常气动力作用下发生变形时,其频率也会发生变化。本文介绍了一种地面电磁干风洞试验方法,利用电磁场和安培力实现气动力的模拟,在不接触模型的情况下对模型进... 详细信息

结构的频率是结构的重要动力学特性,对于飞行器来说,当机翼等大型结构在非定常气动力作用下发生变形时,其频率也会发生变化。本文介绍了一种地面电磁干风洞试验方法,利用电磁场和安培力实现气动力的模拟,在不接触模型的情况下对模型进行静动态加载。基于这种新的试验技术,建立了一种地面电磁干风洞实验方法,利用电磁场和安培力实现气动力的模拟,可有效实现对模型结构的非接触式静态和动态气动力跟随加载。利用该实验系统,研究了静动态条件下,结构质量、刚度分布对飞机内载荷的影响;结构变形对结构动力学特征的影响。结果表明,结构的弯曲变形会影响结构的弯曲和扭转频率,结构的质量和刚度分布会对结构内载荷产生较大影响。这种新的试验方法有利于研究大柔性结构的气动弹性特性,对新型飞机的设计和研制具有重要意义。

关键词：非定常气动力干风洞实验气动弹性大变形机翼准模态试验

Simulation of higher order modes and loss factor of a new type of 500-MHz single cell superconducting cavity at SSRF

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Nuclear Science and Techniques 2011年第5期22卷 257-260页

作者： YU Haibo LIU Jianfei hou Hongtao LU Changwang WEI Yelong MA Zhenyu FENG ziqiang MAO Dongqing Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China Graduate University of Chinese Academy of Sciences Beijing 100049 China Shanghai Key Lab of Cryogenics ＆ Superconducting RF Technology Shanghai 201800 China

In this paper,higher order modes(HOMs) and loss factor of a new type of 500-MHz superconducting cavity is studied,by simulating its broadband HOMs damping at different positions of the ferrite HOM-absorber and different lengths of the *** results show that the impedance and Q value of the HOMs in transverse and longitudinal modes could be greatly *** HOM longitudinal impedance could be damped to meet the requirement of SSRF beam instability *** calculated loss factor of the new SC cavity was compared with cavities at *** was estimated that the HOM absorber could absorb a total power of 3.16 kW at 4-mm beam bunch length.

关键词：损耗因子高阶模超导腔光源上海模拟单细胞纵向阻抗

有限温度及运动背景下的全息Schwinger效应

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中国科学:物理学、力学、天文学 2023年第9期53卷 166-173页

作者：刘杨康侯德富张自强华中师范大学物理科学与技术学院粒子物理研究所夸克与轻子物理教育部重点实验室武汉430079 中国地质大学(武汉)数理学院武汉430074

本文利用势分析的方法研究超标度破坏因子θ和动力学指数z对全息Schwinger效应的影响.其中θ描述对偶场理论中超标度的破坏,z描述系统在相变附近的行为.结果表明,随着θ的增加,Schwinger效应减弱,而动力学指数z增强了Schwinger效应.此外... 详细信息

本文利用势分析的方法研究超标度破坏因子θ和动力学指数z对全息Schwinger效应的影响.其中θ描述对偶场理论中超标度的破坏,z描述系统在相变附近的行为.结果表明,随着θ的增加,Schwinger效应减弱,而动力学指数z增强了Schwinger效应.此外,还发现背景电荷Q(或化学势)和速度β的存在也增强Schwinger效应.

关键词：引力/规范理论对偶超标度破坏 Schwinger效应

Changes in the Chinese Population's Fertility Intentions:1980-2011

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Social Sciences in China 2015年第1期36卷 46-63页

作者：侯佳伟 Huang Silin Xin ziqiang Sun Ling Zhang Hongchuan Dou Donghui Zhao Yuanyuan School of Social Development Central University of Finance and Economics

On the basis of the findings of 227 surveys of Chinese fertility intentions over the years 1980-2011, this paper investigates the longitudinal changes in fertility intentions through cross-temporal meta-analysis. It is found that the ideal number of children for the Chinese trended downwards from 1980, but since 2000 the average number has remained basically stable at 1.6 to 1.8. In the 1980s, people＇s fertility levels were higher than their fertility intentions. With economic and educational progress in China, both fertility levels and fertility intentions showed a downward trend, with the former declining faster than the latter. Since 1990, people＇s fertility levels have been lower than their fertility intentions; that is, their actual number of children has been less than their ideal number. This provides an empirical basis for examining the changes in China＇s fertility intentions and fertility levels.

关键词： fertility intentions ideal number of children gender preference fertility level cross-temporal recta-analysis