检索结果-南通市图书馆

Effect of multiple parameters on the supersonic gas-jet target characteristics for laser wakefield acceleration

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2021年第7期32卷 90-98页

作者： Qiu-Shi Liu Ming-Jiang Ma Bao-zhen zhao Xiao-hua Zhang Chong Lv xiang-Hao Meng Ji Zhang Xiao-Na Ban zhao Wang Xiao-Feng Xi Bao-Xian Tian Chuang-Ye He Bing Guo Department of Nuclear Physics China Institute of Atomic EnergyBeijing 102413China

The supersonic gas-jet target is an important experimental target for laser wakefield acceleration(LWFA),which has great potential for driving novel radiation sources such as betatron radiation and Compton scattering gamma *** to different electron acceleration requirements,it is necessary to provide specific supersonic gas jets with different density profiles to generate electron beams with high quality and high repetition *** this study,the interference images and density profiles of different gas-jet targets were obtained through a modified Nomarski interference diagnosis *** relationships between the gas density and back pressure,nozzle structure,and other key parameters were *** with different characteristics are conducive to meeting the various requirements of LWFA.

关键词： Supersonic gas-jet target Laser wakefield acceleration Electron acceleration Optical interference diagnosis

Self-powered broadband kesterite photodetector with ultrahigh specific detectivity for weak light applications

在线全文

学校读者我要写书评

暂无评论

SusMat 2023年第5期3卷 682-696页

作者： Guang-xing Liang Chuan-Hao Li Jun zhao Yi Fu Zi-Xuan Yu zhuang-Hao zheng zheng-hua Su Ping Fan xiang-hua Zhang Jing-Ting Luo Liming Ding Shuo Chen Shenzhen Key Laboratory of Advanced Thin Films and Applications Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong ProvinceCollege of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhenChina Institut des Sciences Chimiques de Rennes Universite de RennesRennesFrance Center for Excellence in Nanoscience(CAS) Key Laboratory of Nanosystem and Hierarchical Fabrication(CAS)National Center for Nanoscience and TechnologyBeijingChina

Kesterite Cu_(2)ZnSn(S,Se)_(4)(CZTSSe)is a promising candidate for photodetector(PD)applications thanks to its excellent optoelectronic *** this work,a green solution-processed spin coating and selenization-processed thermodynamic or kinetic growth of high-quality narrow bandgap kesterite CZTSSe thin film is developed.A self-powered CZTSSe/CdS thin-film PD is then successfully *** optimization of light absorber and heterojunction interface,especially tailoring the defect and carrier kinetics,it can achieve broadband response from300 to 1300 nm,accompaniedwith a high responsivity of 1.37A/W,specific detectivity(D*)up to 4.0×10^(14)Jones under 5 nW/cm^(2),a linear dynamic range(LDR)of 126 dB,and a maximum Ilight/Idark ratio of 1.3×10^(8)within the LDR,and ultrafast response speed(rise/decay time of 16 ns/85 ns),representing the leading-level performance to date,which is superior to those of commercial andwell-researched ***,an imaging system with a 905nm laser is built for weak light response evaluation,and can respond to 718 pW weak light and infrared imaging at a wavelength as low as 5 nW/*** has also been employed for photoplethysmography detection of pulsating signals at both the finger and wrist,presenting obvious arterial blood volume changes,demonstrating great application potential in broadband and weak light photodetection scenarios.

关键词： detectivity kesterite photodetector thin film weak light detection

Growth and Morphology of β–FeSi_(2) Single Crystal with Chemical Vapor Transport

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 1999年第3期16卷 208-210页

作者： zhao Jian-hua LI Yan-chun LIU Ri-ping ZHANG xiang-yi ZHOU zhen-hua WANG Chao-ying XU Ying-fan WANG Wen-kui Institute of Physics Chinese Academy of SciencesBeijing 100080 Institute of Materials Science and Engineering Yanshan UniversityQinhuangdao 066004

Single crystals ofβ–FeSi_(2) have been grown from vapor by employing chemical vapor transport technique and using iodine as transport agent in a closed *** the experiment,β–FeSi_(2) single crystals with well-developed faces and edges have been observed on the silicon substrate,but no needlelike ones have been *** changes in the size and the geometric shape of the growth ampoule and temperature gradient are primary factors which result in the variation on β–FeSi_(2) single crystal morphology.

关键词： morphology. Crystal transport

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

台阶式凸模精冲工艺分析及数值模拟

塑性工程学报 2012年第1期19卷 55-59页

作者：卫万周向华庄新村赵震黄新华上海交通大学模具CAD国家工程研究中心上海200030

采用平面压板的无齿圈精冲,可以有效降低模具制造成本,提高精冲材料利用率。但采用常规平面压板精冲很难获得较好的冲裁面质量。文章对常规平面压板精冲模具进行改进,通过采用台阶式凸模结构实现无齿圈精冲;采用DEFORM 2DTM软件对C20E-E... 详细信息

采用平面压板的无齿圈精冲,可以有效降低模具制造成本,提高精冲材料利用率。但采用常规平面压板精冲很难获得较好的冲裁面质量。文章对常规平面压板精冲模具进行改进,通过采用台阶式凸模结构实现无齿圈精冲;采用DEFORM 2DTM软件对C20E-EN钢圆盘的台阶式凸模精冲过程建立轴对称模型进行有限元模拟,分析凸模台阶高度、台阶宽度和冲裁间隙等工艺参数对零件冲裁面光洁带高度和塌角高度的影响规律,获得了相对最佳工艺参数的配合方式。将模拟结果与台阶式凸模精冲实验结果进行比较表明,模拟结果和实验结果具有较好的一致性。

关键词：精冲无齿圈台阶式凸模冲裁面有限单元法

Effects of Cu addition on microstructure and mechanical properties of Er-modified Al-10Mg_(2)Si cast alloys

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2022年第3期29卷 795-806页

作者： WU Xiao-feng WANG zhen-cheng CHENG Ting WANG Ke-yan xiang Jun zhao Rong-da CHEN Shun-hua WU Fu-fa School of New Energy Vehicles Nanchang Institute of Science and TechnologyNanchang 330013China School of Materials Science and Engineering Liaoning University of TechnologyJinzhou 121001China School of Mechanical Engineering Hefei University of TechnologyHefei 230009China

The solidification microstructure and mechanical properties of hypoeutectic Al-10Mg_(2)Si cast alloys with different Cu contents and 0.45 wt.% Er were investigated using an optical microscope, scanning electron microscope, and an electronic universal testing machine. Results showed that Cu and Er could significantly reduce the grain size of the eutectic Mg;Si phase from 15.4 μm for the base alloy to 5.8 μm for the alloy with 1.5 wt.% Cu and 0.45 wt.% ***, the needle-like β-Al5Fe Si phase was modified to fine sized irregular shaped Cu, Er and Fe-rich particles with the additions of Cu and Er. The strength and ductility of the Al-10Mg_(2)Si as-cast alloys were simultaneously improved by the additions of Cu and Er, and the ultimate tensile strength, yield strength and elongation increase from 223 MPa,136 MPa and 2.1% to 337 MPa, 169 MPa and 4.7%, respectively. The heterogeneous nucleation of Mg_(2)Si on Al P was avoided by forming Cu, Er and P-containing phases, due to the additions of Cu and Er. Moreover, the Cu and Er atomic clusters and their intermetallic segregated on the surface of the eutectic Mg_(2)Si and inhibited the growth of the eutectic Mg_(2)Si, which were responsible for the modification of the eutectic Mg_(2)Si.

关键词： Al-Mg_(2)Si alloy Cu Er eutectic Mg_(2)Si mechanical properties

A fiber bundle structure with uniform transmission characteristics for high-density astronomical optical cables

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2019年第8期19卷 131-142页

作者： Qi Yan Tao Geng Hang Jiang Chuang zhao Ying-hua Zhang An-Zhi Wang Jia-Bin Wang Xi-Ren Jin Xu-Dong Chen Chun-Lian Lu Liang Wang Zhi-xin huang Jing-Dong zhuang Song Wang Wei-Min Sun xiang-Qun Cui Key Lab of In-fiber Integrated Optics Ministry Education of ChinaHarbin Engineering UniversityHarbin150001China Yangtze Optical Fibre and Cable Joint Stock Limited Company Wuhan430073China Nanjing Institute of Astronomical Optics and Technology National Astronomical ObservatoriesChinese Academy ofSciencesNanjing210042China

Transmission efficiency(TE) and focal ratio degradation(FRD) are two important parameters for evaluating the quality of an optical fiber system used for astronomy. Compared to TE, the focal ratio is more easily influenced by external factors, such as bending or stress. Optical cables are widely implemented for multi-object telescopes and integral field units(IFUs). The design and fabrication process of traditional optical cables seldom considers the requirements of astronomical applications. In this paper, we describe a fiber bundle structure as the basic unit for miniaturized high-density FASOT-IFU optical cables,instead of the micro-tube structure in stranded cables. Seven fibers with hexagonal arrangement were accurately positioned by ultraviolet(UV)-curing acrylate to form the bundle. The coating diameter of a fiber is0.125 mm, and the outer diameter of the bundle is 0.58 mm. Compared with the 0.8 mm micro-tube structure of a traditional stranded cable, the outer diameter of the fiber bundle was reduced by 27.5%. Fiber paste was filled into the bundle to reduce stress between the fibers. We tested the output focal ratio(OFR) in95% of the encircled energy(EE95) of the fibers in the bundle under different conditions. With the incident focal ratio F/8, the maximum difference of OFR is 0.6. In particular, when the incident focal ratio is F/5,the maximum difference of OFR is only 0.1. The jacket formed by the UV-curing acrylate can withstand a certain stress of less than 1.38 N mm-1. The fiber bundle can maintain uniform emitting characteristics with a bending radius of 7.5 cm and with tension less than 6 N. The test results show that the structure of the fiber bundle can be used as a basic unit for miniaturized high-density astronomical optical cables.

关键词： instrumentation:spectrographs techniques:imaging spectroscopy techniques:spectroscopic methods:miscellaneous

基于低共熔溶剂同时清洗植物性食品中多种污染元素可行性研究

在线全文

学校读者我要写书评

暂无评论

食品安全质量检测学报 2024年第9期15卷 178-186页

作者：陈玉珍梁志森李建华尧向洁黄伟乾廖启照广州检验检测认证集团有限公司广州511447 国家加工食品质量检验检测中心(广东) 广州511447

目的探究基于低共熔溶剂(deep eutectic solvents,DESs)同时清洗植物性食品中多种污染元素的可行性。方法室温下,以六偏磷酸钠为氢键受体,D-葡萄糖酸、山梨醇和尿素为氢键供体制备3种新型DESs,即六偏磷酸钠-D-葡萄糖酸(sodium hexametap... 详细信息

目的探究基于低共熔溶剂(deep eutectic solvents,DESs)同时清洗植物性食品中多种污染元素的可行性。方法室温下,以六偏磷酸钠为氢键受体,D-葡萄糖酸、山梨醇和尿素为氢键供体制备3种新型DESs,即六偏磷酸钠-D-葡萄糖酸(sodium hexametaphosphate-gluconic acid,SHMP-Glc A)、六偏磷酸钠-山梨醇(sodium hexametaphosphate-sorbitol,SHMP-Sbt)及六偏磷酸钠-尿素(sodium hexametaphosphate-urea,SHMP-Ur),测定3种DESs的黏度、密度、熔点和p H,并利用傅里叶变换红外光谱法(Fourier transform infrared spectroscopy,FTIR)、热重法(thermo-gravimetry,TG)进行表征。超声辅助下,将3种DESs用于清洗植物性食品中22种污染元素,利用电感耦合等离子体质谱法(inductively coupled plasma-mass spectrometry,ICP-MS)测定清洗前后样品中7种重金属元素(Mn、Ni、Cu、Zn、Cd、Ba和Pb)、1种类金属元素(As)、14种稀土元素(La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb和Lu)的含量,并探究DESs的残留量。结果DESs的黏度、密度和熔点与氢键的形成有关,FTIR结果表明DESs中存在氢键。p H与DESs前体组分有关。SHMP-Glc A、SHMP-Sbt和SHMP-Ur的分解温度分别为185、348和167℃。与纯水清洗对照相比,DESs对植物性食品中多种污染元素的清洗效果大幅提高;变异系数法赋权综合评分显示,SHMP-Glc A对元素的去除率最优(综合评分0.6281),次之SHMP-Ur(综合评分-0.1335),SHMP-Sbt第三(综合评分-0.4946)。DESs在样品中残留的磷元素含量不超过磷酸盐类物质的每日最大容许摄入量(70 mg/kg bw,以P计)。结论制备的低挥发性的新型DESs能高效去除植物性食品中多种污染元素,在保障食品安全方面具有应用前景。

关键词：低共熔溶剂植物性食品多种污染元素清洗变异系数法

Emerging Variants of B.1.617 Lineage Identified Among Returning Chinese Employees Working in India—Chongqing Municipality,China,April 2021

在线全文

学校读者我要写书评

暂无评论

China CDC weekly 2021年第19期3卷 409-410页

作者： Sheng Ye Yongjun Zhang xiang zhao zhen Yu Yang Song Zhangping Tan Yun Tang Shuang Chen Mingyue Wang hua Ling Chongqing Center for Disease Control and Prevention ChongqingChina Chongqing Medical and Pharmaceutical College ChongqingChina National Institute for Viral Disease Control and Prevention China CDCBeijingChina.

On April 22 and 23,2021,3 confirmed COVID-19 cases in passengers on an arriving airplane from Nepal were reported by Chongqing Public Health Medical *** epidemiological investigation revealed these 3 patients,males aged 20-30 years,were coworkers of a cellphone company that has a manufacturing base in Noida,India,where they worked with their Indian colleagues since late 2019.

关键词： Chongqing India fir

Validity and Reliability of Chinese Physical Activity Questionnaire for Children Aged 10-17 Years

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Biomedical and Environmental Sciences 2019年第9期32卷 647-658页

作者： YANG Xi JAGO Russell ZHAI Yi YANG zhen Yu WANG Yu Ying SI xiang WANG Jun GAO Jian Fen CHEN Jing Ron YU Ying Jie zhao Wen hua National Institute for Nutrition and Health Chinese Center for Disease Control and PreventionBeijing 100050China Chinese Center for Disease Control and Prevention Beijing 102206China Center for Exercise Nutrition and Health SciencesSchool for Policy StudiesUniversity of BristolBristol BS8 1TZUK Beijing Tiantan Hospital Capital Medical UniversityBeijing 100050China Wanzhou District Center for Disease Control and Prevention Chongqing 404000China Yanqing District Center for Disease Control and Prevention Beijing 102100China Chongqing Center for Disease Control and Prevention Chongqing 400042China Beijing Center for Disease Prevention and Control Beijing 100013China

Objective This study is aimed to report the development,the reliability and validity of the Chinese Children Physical Activity Questionnaire(CCPAQ)which was designed for the assessment of physical activity pattern in young population in *** The CCPAQ was administered for two times in 119 children(mean age 13.1±2.4 years;boys 47%)to examine reliability by using intraclass correlation *** was determined in 106 participants by agreement with the CCPAQ measures and the objective method,the ActiGraph *** on physical activity patter n including time spe nt on d iff ere nt intensi ties and total physical activity,sedentary behavior as well as physical activity energy expenditure were used to assess the validity with Spearman's correlation coefficient and the Bland-Altman *** The reliability coefficient of the CCPAQ ranged from 0.63-0.93(Intra-class correlation coefficient).Spearman's correlation coefficient for validity of time spent on total physical activity and sedentary behavior were all 0.32(P<0.001),and for physical activity energy expenditure was 0.58(P<0.001).Time spent on moderate-to-vigorous physical activity and light physical activity showed a relatively low correlation with the accelerometer(rho=0.20,P=0.040;rho=0.19,P=0.054).Conclusion The CCPAQ appears to be a promising and feasible method to assess physical activity pattern in Chinese children.

关键词： Physical activity Sedentary behavior Child Questionnaire Validity and reliability