Improved Quantum Signature Scheme with Weak Arbitrator

In this paper, we find a man-in-the-middle attack on the quantum signature scheme with a weak arbitrator (Luo et al., Int. J. Theor. Phys., 51:2135, 2012). In that scheme, the authors proposed a quantum signature based on quantum one way function which contains both verifying the signer phase and verifying the signed message phase. However, after our analysis we will show that Eve can adopt different strategies in respective phases to forge the signature without being detected. Then we present an improved scheme to increase the security.     

Nanoscale gap filling for phase change material by pulsed deposition and inductively coupled plasma etching

The gap filling of phase change material has become a critical module in the fabrication process of phase change random access memory (PCRAM) as the device continues to scale down to 45 nm and below. However, conventional physical vapor deposition process cannot meet the nanoscale gap fill requirement anymore. In this study, we found that the pulsed deposition followed by inductively coupled plasma etching process showed distinctly better gap filling capability and scalability than single-step deposition process. The gap filling mechanism of the deposit–etch–deposit (DED) process was briefly discussed. The film redeposition during etching step was the key ingredient of gap filling improvement. We achieved void free gap filling of phase change material on the 30 nm via with aspect ratio of 1:1 by two-cycle DED process. The results provided a rather comprehensive insight into the mechanism of DED process and proposed a potential gap filling solution for 45 nm and below technology nodes for PCRAM.     

Stable single longitudinal mode erbium-doped silica fiber laser based on an asymmetric linear three-cavity structure

We present a stable linear-cavity single longitudinal mode (SLM) erbium-doped silica fiber laser. It consists of four fiber Bragg gratings (FBGs) directly written in a section of photosensitive erbium-doped fiber (EDF) to form an asymmetric three-cavity structure. The stable SLM operation at a wavelength of 1545.112 nm with a 3-dB bandwidth of 0.012 nm and an optical signal-to-noise ratio (OSNR) of about 60 dB is verified experimentally. Under laboratory conditions, the performance of a power fluctuation of less than 0.05 dB observed from the power meter for 6 h and a wavelength variation of less than 0.01 nm obtained from the optical spectrum analyzer (OSA) for about 1.5 h are demonstrated. The gain fiber length is no longer limited to only several centimeters for SLM operation because of the excellent mode-selecting ability of the asymmetric three-cavity structure. The proposed scheme provides a simple and cost-effective approach to realizing a stable SLM fiber laser.     

An optical study of the D-D neutron irradiation-induced defects in Co-and Cu-doped ZnO wafers

Room-temperature photoluminescence and optical transmittance spectroscopy of Co-doped(1×1014,5×1016,and 1×1017cm-2) and Cu-doped(5×1016cm-2) ZnO wafers irradiated by D-D neutrons(fluence of 2.9×1010 cm-2) have been investigated.After irradiation,the Co or Cu metal and oxide clusters in doped ZnO wafers are dissolved,and the wu¨rtzite structure of ZnO substrate for each sample remains unchanged and keeps in high c-axis preferential orientation.The degree of irradiation-induced crystal disorder reflected from the absorption band tail parameter(E0) is far greater for doped ZnO than the undoped one.Under the same doping concentration,the Cu-doped ZnO wafer has much higher irradiation-induced disorder than the Co-doped one.Photoluminescence measurements indicate that the introduction rate of both the zinc vacancy and the zinc interstitial is much higher for the doped ZnO wafer with a high doping level than the undoped one.In addition,both crystal lattice distortion and defect complexes are suggested to be formed in doped ZnO wafers.Consequently,the Co-or Cu-doped ZnO wafer(especially with a high doping level) exhibits very low radiation hardness compared with the undoped one,and the Cu-doped ZnO wafer is much less radiation-hard than the Co-doped one.     

S波段相对论速调管放大器锁相特性

对相对论速调管放大器（RKA）锁相特性进行了粒子模拟与实验研究。在2.5维粒子模拟中,研究了电子束电压波形特征对RKA锁相特性的影响,结果表明:电子束电压波形上冲对RKA锁相特性有正面影响,即能够减小相位差达到锁定状态的时间,幅度为20%的上冲导致大约23的相位差变化;波形顶降则对RKA锁相特性有负面影响,可使相位差过早地偏离稳定值,幅度为5%的顶降大约能引起50的相位差偏离;电压波形的上升时间对RKA相位锁定特性也有影响,但规律不明显。在三维粒子模拟和实验中,研究了导引磁场大小对RKA锁相特性的影响,结果表明,在1.6 T以下,RKA输出微波与种子源微波之间的相位差锁定值总体上随导引磁场的增大而减小,在细节上,呈现阶跃形式,即一定范围内导引磁场大小变化不会导致相位差的改变。实验研究表明,在导引磁场范围为0.6~1.2 T时,RKA锁定相位差随导引磁场的增大而减小,阶跃现象不明显。     

129I加速器质谱分析研究

通过对129I加速器质谱(AMS)分析中影响敏度和准确度各种参数的研究,如靶电极制备、压样、靶样中辅助介质（Matrix）的选择及使用比例等,优化了用于3 MV加速器质谱仪的SO-110型离子源的条件参数,确定129I-AMS测量的最佳靶电极材料为Cu,最佳的辅助介质为Nb粉末,Nb与AgI样品的最佳体积比为3∶1。在此条件下可以获得稳定且持续的I-束流进行测量129I/127I原子比值,实验测得西安加速器质谱仪的129I/127I本底值为1.5210-14。     

离子注入n型GaN光致发光谱中宽黄光发射带研究

利用离子注入方法和光致发光技术系统研究了注入离子对n型GaN宽黄光发射带的影响.实验采用的注入离子为：N，O，Mg，Si和Ga，剂量分别为10¹³，10¹⁴，10¹⁵和10¹⁶/cm²，注入温度为室温.注入后的样品在900 ℃流动氮气环境下进行热退火，退火时间为10 min，并对退火前后的样品分别进行室温光致发光测量.通过实验数据的分析，独立提出了提取注入离子对晶体黄光发光特性影响的半经验模型.利用该模型导出的公式，可以确定注入的N，O，Ga，Mg和Si离子对黄光发射带的影响随注入剂量的变化关系以及该影响的相对强弱. 关键词： 氮化镓 光致发光谱 离子注入     

拟南芥胚的不同区域对MeV离子辐照的响应

利用不同能量的质子在大气环境中辐照拟南芥的含水种子，能量从1.1MeV到6.5MeV.根据模拟计算结果，相应能量的离子对种子的损伤区域分别为胚的浅层、胚的一半和整个胚.本实验中，具有较高能量的质子可以完全均匀地作用于拟南芥生长、发育及遗传密切相关的胚茎端分生组织，而能量较低的质子则不能直接作用于茎端分生组织.实验所用质子注量范围为4×10⁹ions/cm²—1×10¹⁴ions/cm².实验结果显示，虽然拟南芥种子的发芽率和幼苗存活率随离子注量增加都呈现下降的趋势，但对应于不同的胚损伤区域，即在不同的入射质子能量条件下，注量曲线具有各自的特征.实验结果显示，拟南芥种子中除了胚茎端分生组织作为对离子辐照敏感的辐射主靶外，茎端分生组织之外的胚区域可能作为离子辐射次靶，影响到最终的辐射生物学效应. 关键词： 离子辐照 拟南芥 胚区域 生物效应     

高反射率p-GaN欧姆接触电极

根据光学薄膜原理计算了GaN/Ti/Ag、GaN/Al和GaN/Ni/Au/Ti/Ag、GaN/Ni/Au/Al多层电极结构的反射率,得出Ag基和Al基反射电极均能在全角范围内提供较高的反射率。实验测量结果表明,反射率能高于80%的Ag基反射电极,具有低欧姆接触的电学特性。并将GaN/Ni/Au/Ti/Ag多层反射电极应用在上下电极结构的GaN基LED中。实验上采用两步合金法获得了低接触电阻、高反射率的电极结构,并引入Ni/Au覆盖层克服了Ag高温时的团聚和氧化现象。解决了Ag电极的稳定性问题,显著地提高了LED的出光效率,成功制备了具有上下电极结构的GaN基LED管芯。     

生物添加剂对汽油机燃油经济性及废气排放影响的研究

将一种棕榈油提取物作为添加剂,加入汽油中以研究其对汽油机燃油经济性和排放品质的影响。针对市场上正使用的辛烷值为93#的高清洁汽油和乙醇汽油,通过发动机台架试验对加剂前后的汽油机性能指标进行了对比和分析．结果表明:加入此种添加剂后对各种汽油的燃油经济性有大幅改善作用,对乙醇汽油的效果尤甚。加剂后可以使乙醇汽油的燃油经济性与普通汽油完全一样。对于93#高清洁汽油,除了未燃碳氢(HC)略有上升外,其他排放物如氮氧化物 (Nox)、一氧化碳等有所减少, CO2排放有明显的改善。对于乙醇汽油,则HC和CO2略有上升。