SHER-HIAF ring lattice design

The Super Heavy Experimental Ring (SHER), which is one of the rings of the next accelerator complex High Intensity Heavy Ion Accelerator Facility (HIAF) at IMP, has to be optimized for e-cooling. Its lattice is designed for two modes: the first is the isochronous mode, which is a time-of-flight mass spectrometer for short-lived secondary nuclei, the second is the storage ring mode, which is used for collecting and cooling the secondary rare isotope beams from the transport line. In order to fulfil its purpose, the ion optics can be set to different ion optical modes.     

Radio-Frequency Performance of Epitaxial Graphene Field-Effect Transistors on Sapphire Substrates

We report dc and the first-ever measured small signal rf performance of epitaxial graphene field-effect transistors （GFETs）, where the epitaxial graphene is grown by chemical vapor deposition （CVD） on a 2-inch c-plane sapphire substrate. Our epitaxial graphene material has a good flatness and uniformity due to the low carbon concentration during the graphene growth. With a gate length Lg = 100 nm, the maximum drain source current Ids and peak transconductance gm reach 0.92 A/mm and 0.143 S/mm, respectively, which are the highest results reported for GFETs directly grown on sapphire. The extrinsic cutoff frequency （fT） and maximum oscillation frequency （fmax） of the device are 12 GHz and 9.5 GHz, and up to 32 GHz and 21.5 GHz after de-embedding, respectively. Our work proves that epitaxial graphene on sapphire substrates is a promising candidate for rf electronics.     

HIAF中环形质量谱仪SRing的线性设计

为了精确测量短寿命原子核质量,提出了在强流重离子加速器装置(HIAF)上建造高精度环形质量谱仪SRing。SRing长188.7 m,最大设计磁刚度为1 3 T·m,主要由磁聚焦结构、注入系统、引出系统、随机冷却以及探测系统等组成。SRing将运行在等时性模式和收集模式下用于短寿命原子核质量的精确测量和放射性次级束流收集并纯化。详细介绍了SRing的线性光学设计,并给出两种模式下的光学设计、注入及引出系统的设计等,设计参数优化完毕后,机器测量精度有望提高到10~6。     

富勒烯有机-无机杂化材料的非共珍三阶非线性光学特性

采用中心波长800 nm、脉宽30 fs的超短激光脉冲,通过飞秒光开关技术（Optical Kerr Shutter,OKS）对富勒烯有机-无机杂化材料的飞秒超快非线性特性进行了实验研究.获得270 fs的开关时间,所得的富勒烯有机-无机杂化材料的三阶非线性系数χ(3)约为4.5×10－14 esu,比C60分子的三阶非线性系数χ(3)高一个数量级.通过实验测定的光克尔信号强度与激发光和探测光偏振方向夹角的依赖关系表明：30 fs的超短激光脉冲激发富勒烯有机-无机杂化材料的克尔信号主要是源于光诱导双折射效应,而非用200 fs的超短激光脉冲时来自瞬态栅的自衍射效应.     

Comparison of electrical characteristic between AIN/GaN and AIGaN/GaN heterostructure Schottky diodes

Ni/Au Schottky contacts on A1N/GaN and A1GaN/GaN heterostructures are fabricated. Based on the measured current-voltage and capacitance-voltage curves, the electrical characteristics of AlN/GaN Schottky diode, such as Schottky barrier height, turn-on voltage, reverse breakdown voltage, ideal factor, and the current-transport mechanism, are analyzed and then compared with those of an A1GaN/GaN diode by self-consistently solving Schrodinger＇s and Poisson＇s equations. It is found that the dislocation-governed tunneling is dominant for both AlN/GaN and AlGaN/GaN Schottky diodes. However, more dislocation defects and a thinner barrier layer for AlN/GaN heterostrncture results in a larger tunneling probability, and causes a larger leakage current and lower reverse breakdown voltage, even though the Schottky barrier height of AlN/GaN Schottky diode is calculated to be higher that of an A1GaN/GaN diode.     

烷基糖苷-十二烷基甜菜碱复配性能及无机盐的影响

本文考察了非离子型表面活性剂烷基糖苷（APG）和两性表面活性剂十二烷基甜菜碱（BS-12）之间的复配性能,测定了不同摩尔比的APG和BS-12复配体系的表面张力、泡沫和乳化性能,并且研究了无机盐对复配体系表面活性的影响情况。研究结果表明,APG和BS-12复配体系与单独任一表面活性剂体系相比具有较好的表面活性,两者具有明显的协同增效作用,且在摩尔比为3:7时,复配体系的表面活性最高、起泡性能最好、形成的泡沫和乳状液最稳定,协同增效作用最显著。此外,无机盐的加入提高了复配体系的表面活性,当NaCl浓度为0.0     

新型3-烯色满酮拼接季碳氧化吲哚类化合物的合成

以色酮取代氧化吲哚（1）为原料,在有机碱DABCO的催化作用下,进攻3-烯色满酮2的烯键,发生Michael加成反应,然后脱除OBoc基团生成烯键,合成了9个未见文献报道的3-烯色满酮拼接季碳氧化吲哚类化合物（3a～3i）,产率60%～87%,dr值为2:1～5:1,其结构经1H NMR,13C NMR和HR-MS（E...     

Γ-环与广义Γ-环的强Jacobson根与拟强Jacobson根

本文定义了Γ-环的强左拟正则理想与拟强左拟正则理想,得到任何Γ-环都有强J-根与拟强J-根,以及强J-根等于拟强J-根等结论,还验证了在广义Γ-环中本文所有结论都能成立。     

含稀土抗蠕变压铸镁合金的开发

针对商用压铸镁合金抗高温蠕变性能较差的现状，开发了抗高温蠕变压铸镁合金，其开发的目的是针对大马力柴油发动机汽缸罩盖，其抗高温蠕变性能应该能够保障其在150℃条件下稳定工作，而且其成本的增加应该控制在AZ91D合金成本的15％以内。讨论了稀土元素Ce，Y，Nd及Ca和Si的添加对压铸镁合金在常温拉伸性能以150℃条件下的蠕变行为、显微组织的影响，以及对表面处理和腐蚀试验的影响，并进行了实际产品的压铸牛产。试验结果表明，所开发的抗蠕变压铸镁合金具有应用于汽车动力系统部件的制造并大幅度减轻重量的潜力。     

正交轨线问题的计算机代数研究

用数学软件 Mathematica 3.0实现单参数曲线族的正交轨线的求解 .使常微分方程中的这一类常见问题得到迅速的解决