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Transverse emittance measurement for the Heavy ion medical machine cyclotron

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Nuclear Science and Techniques 2019年第12期30卷 103-110页

作者： Yong-Chun Feng Min Li Rui-Shi Mao Bing Wang Sheng-Peng Li Wei-Long Li Wei-Nian Ma Xin-Cai Kang Jin-Quan Zhang Peng Li Tie-Cheng Zhao Zhi-Guo Xu You-Jin Yuan Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China Lanzhou Ke jin tai ji Corporation LTDLanzhou 730000China Lanzhou University of Technology Lanzhou 730050China

The transverse emittance of the extracted beam from the Heavy ion medical machine cyclotron is measured and then optimized for injection into the synchrotron.For the purposes of cross-validation,three methods,i.e.,slit-grid,Q-scan,and 3-grid,are used to measure the emittance.In the slit-grid technique,an automatic selection of the region of interest is adopted to isolate the major noise from the beam phase space,which is an improvement over the traditional technique.After iterating over the contour level,an unbiased measurement of the emittance can be obtained.An improvement in the thin lens technique is implemented in the Q-scan method.The results of these measurements are presented.

关键词： Heavy ion medical machine Transverse emittance Slit-grid

Analysis of longitudinal forces of coupler devices in emergency braking process for Heavy haul trains

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Journal of Central South University 2017年第10期24卷 2449-2457页

作者：高广军陈威张洁董海鹏邹翔李健关维元 Key Laboratory of Traffic Safety on Track of Ministry of Education(School of Traffic&Transportation Engineering Central South University)Changsha 410075China

To reduce the longitudinal coupler forces of Heavy haul trains and improve the running safety, the velocity method and New-mark method were used for the coupler simulation and numerical integration, and a numerical model on the longitudinal dynamics of Heavy haul trains was established. Validation was performed against the experimental data. Using this model, the emergency braking process for a combined marshalling Heavy haul train was investigated to obtain the distributions of the longitudinal compressive forces and strokes of coupler devices. Then, the influences of the initial braking velocity, the synchronization time of master and slave locomotives, the coupler stiffness and the vibrator mass on the longitudinal forces and strokes were analyzed. The results show that it should be avoided that the emergency braking starts at a low initial speed. Keeping synchronism between master locomotive and slave locomotives effectively helps to reduce the longitudinal forces. Reducing the coupler stiffness appropriately and adding rigid arm connections, the longitudinal vibration frequency can be brought down and the longitudinal forces will be decreased, which improves the running safety of Heavy haul trains. All of these research results can provide a reference for the operation and development of Heavy haul trains.

关键词： Heavy haul train coupler device longitudinal force emergency braking coupler stiffness vibrator mass

Adsorption models for Heavy metal biosorption

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化工学报 2007年第1期58卷 145-148页

作者：郑成虞启明尹平和 School of Chemistry and Chemical Engineering Guangzhou University School of Environmental Engineering Griffith UniversityNathan CampusBrisbane Department of Chemistry Jinan University

Heavy metal biosorption is an effective process for the removal and recovery of Heavy metal ions.Equilibrium isotherms obtained experimentally are usually correlated empirically with commonly used adsorption models, without considering the underlying mechanisms of biosorption.Commonly used models for correlating biosorption isotherm data are briefly reviewed and the use of the adsorption models in correlating the desorption processes is analysed.A set of biosorption/desorption experiments for a marine alga derived biosorbent are carried out to test the use of the adsorption models in the desorption process.Experimental data indicate that the amount of the Heavy metal ions desorbed from the biomass could not be calculated with the adsorption models.This suggests that the empirical use of adsorption models in the correlation may not be valid when the reversibility of the biosorption equlibrium in the desorption process needs to be considered.Therefore,mechanism based biosorption models are needed for better correlation of equilibrium isotherm data.

关键词： biosorption model Heavy metal ion

Research on the effect of the Heavy nuclei amount on the temperature reactivity coefficient in a small modular molten salt reactor

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Nuclear Science and Techniques 2019年第9期30卷 83-93页

作者： Meng-Lu Tan Gui-Feng Zhu Yang Zou Xiao-Han Yu Ye Dai Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China University of Chinese Academy of Sciences Beijing 100049 China

Small modular thorium-based graphite-moderated molten salt reactors (smTMSRs), which combine the advantages of small modular reactors and molten salt reactors, are regarded as a wise development path to speed deployment time. In a smTMSR, low enriched uranium and thorium fuels are used in once-through mode, which makes a marked difference in their neutronic properties compared with the case when a conventional molten salt breeder reactor is used. This study investigated the temperature reactivity coefficient (TRC) in a smTMSR, which is mainly affected by the molten salt volume fraction (VF) and the Heavy nuclei concentration in the fuel salt (HN). The fourfactor formula method and the reaction rate method were used to indicate the reasons for the TRC change, including the fuel density effect, the fuel Doppler effect, and the graphite thermal scattering effect. The results indicate that only the fuel density has a positive effect on the TRC in the undermoderated region. Thermal scattering from both salt and graphite has a significant negative influence on the TRC in the overmoderated region. The maximal effective multiplication factor, which shows the highest fuel utilization, is located at 10% VF and 12 mol% HN and is still located in the negative TRC region. In addition, on increasing the Heavy nuclei amount from 2 mol% HN to 12 mol% HN (VF = 10%), the total TRC undergoes an obvious change from - 11 to - 3 pcm/K, which implies that the change in the HN caused by the fuel feed online should be small to avoid potential trouble in the reactivity control scheme.

关键词： Molten salt reactor Temperature reactivity coefficient Heavy nuclei amount

Decadal and Interannual Variability of Persistent Heavy Rainfall Events over the Middle and Lower Reaches of the Yangtze River Valley

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Journal of Meteorological Research 2019年第6期33卷 1031-1043页

作者： Ruan YAO Xuejuan REN China Meteorological Administration–Nanjing University Joint Laboratory for Climate Prediction Studies School of Atmospheric SciencesNanjing UniversityNanjing 210023

This study investigates the relationship between the anomalous atmospheric circulation pattern and summertime persistent Heavy rainfall(PHR)over the middle and lower reaches of the Yangtze River valley(MLYRV)on the decadal and interannual timescales.Based on the gridded daily rainfall data of the US Climate Prediction Center,the PHR events on grid-point and the regional PHR events considering both the area of PHR and regionally averaged rainfall intensity are identified over the MLYRV during the summers of 1979–2017.A PHR index(PHRI)is defined,to describe the variability of summertime PHR event number over the MLYRV.The PHRI is then divided into the decadal and interannual components.Further analysis reveals that the decadal PHR events are closely related to anomalous precipitation,intensified vertical motion,and strengthened upper-level divergence over southern China,as well as an anomalous anticyclone over the western Pacific transporting more water vapor from the South China Sea(SCS)to southern China.As for the interannual component,the above pattern still co-exists but over a narrow region around the MLYRV.By choosing the years in which the decadal and interannual components of the PHRI are simultaneously positive(SP)or negative(SN),the features of regional PHR events in SP and SN years are analyzed,respectively.The results show that there are more regional PHR events in SP years with enhanced intensity and larger affected areas compared with those in SN years.Meanwhile,the zonal oscillations of the South Asian high(SAH)and the western Pacific subtropical high(WPSH)during the regional PHR events demonstrate a better regularity in SP years than those in SN years.

关键词： middle and lower reaches of the Yangtze River valley(MLYRV) persistent Heavy rainfall(PHR) decadal variability interannual variability

Heavy cut225数控镗铣床挖刀故障处理

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机床与液压 2013年第20期41卷 143-145页

作者：谢欣华东方电气集团东方电机股份有限公司设备中心四川德阳618000

Heavy cut 225数控镗铣床在加工时随机发生挖刀故障。通过分析发现,工件原点坐标变化是导致挖刀故障的主要原因。针对该故障原因,给出了具体的处理方法,彻底排除了故障。

关键词： Heavy cut 225数控镗铣床挖刀故障故障排除

Heavy-ion and pulsed-laser single event effects in 130-nm CMOS-based thin/thick gate oxide anti-fuse PROMs

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Nuclear Science and Techniques 2019年第5期30卷 92-102页

作者： Chang Cai Tian-Qi Liu Xiao-Yuan Li Jie Liu Zhan-Gang Zhang Chao Geng Pei-Xiong Zhao Dong-Qing Li Bing Ye Qing-Gang Ji Li-Hua Mo Institute of Modern Physics Chinese Academy of Sciences University of Chinese Academy of Sciences School of Physical Science and Technology Lanzhou University Academy of Shenzhen State Microelectronic Co. Ltd. Science and Technology on Reliability Physics and Application of Electronic Component Laboratory

Single event effects of 1-T structure programmable read-only memory(PROM) devices fabricated with a 130-nm complementary metal oxide semiconductorbased thin/thick gate oxide anti-fuse process were investigated using Heavy ions and a picosecond pulsed laser. The cross sections of a single event upset(SEU) for radiationhardened PROMs were measured using a linear energy transfer(LET) ranging from 9.2 to 95.6 MeV cm^2mg^(-1).The result indicated that the LET threshold for a dynamic bit upset was ～ 9 MeV cm^2mg^(-1), which was lower than the threshold of ～ 20 MeV cm^2mg^(-1) for an address counter upset owing to the additional triple modular redundancy structure present in the latch. In addition, a slight hard error was observed in the anti-fuse structure when employing209 Bi ions with extremely high LET values(～ 91.6 MeV cm^2mg^(-1)) and large ion fluence(～ 1×10~8 ions cm^(-2)). To identify the detailed sensitive position of a SEU in PROMs, a pulsed laser with a 5-μm beam spot was used to scan the entire surface of the device.This revealed that the upset occurred in the peripheral circuits of the internal power source and I/O pairs rather than in the internal latches and buffers. This was subsequently confirmed by a ^(181)Ta experiment. Based on the experimental data and a rectangular parallelepiped model of the sensitive volume, the space error rates for the used PROMs were calculated using the CRèME-96 prediction tool. The results showed that this type of PROM was suitable for specific space applications, even in the geosynchronous orbit.

关键词： Anti-fuse PROM Single event effects Heavy ions Pulsed laser Space error rate

Heavy metals contents in soil profiles of typical agricultural lands in Yixing,Jiangsu Province,China

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Chinese Science Bulletin 2008年第S1期53卷 177-187页

作者： Zhou ShengLu Liao FuQiang Wu ShaoHua Zhang HongFu Ren Kui Nanjing Univ Sch Geog & Oceanog Sci Nanjing 210093 Peoples R China

The effect of land use pattern on the Heavy metals(HMs)distribution in soil profiles was investigated in Yixing City,China,for the four typical types of land utilization,i.***.vegetable fields on the plain,paddy fields,tea gardens on hilly lands and bamboo groves.The variance of HMs concentration in the depth of 0-15 cm,15-30 cm,30-60 cm of soil profiles was compared among the different tillage ages. Results showed there was a notable accumulation of Cd,Hg,Cu,Pb,Zn and Cr in the soil profiles of vegetable fields and paddy fields causing a pollution of Cu,Hg and Cd in some profiles,while no remarkable accumulation of HMs in the soil profiles of the tea gardens and bamboo groves was found. The accumulation extent of HMs in the soil profiles of the four kinds of land use followed a sequence of vegetable fields>paddy fields>tea gardens>bamboo groves.The accumulation of HMs was mainly due to the industry,transportation,other urban human activities,and intensive use of fertilizers and pesticides.The downward leaching of HMs was relatively remarkable in the soil profiles of vegetable fields. There was an accumulation in surface and subsurface layers for Cd,Hg,Pb,Zn in the soil profiles of paddy fields and tea gardens,and for Cd,Hg in those of bamboo groves.Serious pollution effects of Hg, Pb,and Zn have been shown in the soil of vegetable fields.All the four kinds of agricultural land are basically free from the pollution of the external sources of As and Ni.With the increase of tillage time, the soil of vegetable and paddy fields will face the potential risk of HMs pollution,which mainly comes from Hg,Cd and Cu,whereas that of tea gardens and bamboo groves faces a relatively small risk.

关键词： Heavy metals soil profile typical use of land term of development and utilization variance of time

指数收益率的波动率预测——基于Heavy模型和GARCH模型

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时代金融 2021年第1期 65-68页

作者：张云杰首都经济贸易大学

本文以具有代表性的9个中国股市指数的高频价格和每日收盘价(时间窗口是2013年至2018年)作为数据源,比较广义自回归条件异方差模型(简称GARCH模型,下同)和high-frequency-basedvolatilitymodels(简称Heavy模型,Shephard和Sheppard(2010),下同)的预测精度。把整体数据源分为样本内数据和样本外数据,样本内数据用于参数估计,样本外数据用于模型预测。然后通过损失函数计算损失值,损失函数值越小,则模型的预测效果越好。最后通过Diebold-Mariano检验统计量判定两个模型优劣的显著性。结果是Heavy模型整体比GARCH模型预测效果要好。

关键词： GARCH Heavy 最大似然估计损失函数 Diebold-Mariano检验统计量