真值、随机误差、系统误差的新定义

我国计量技术规范《JJF1001—1998通用计量术语及定义》对真值、随机误差和系统误差给予了新的定义,对过去的定义作了原则上的改变.本文对新定义的科学性和合理性进行了讨论,并建议在大学物理实验教学和教材中采用.     

Attacks and Improvement of Quantum Sealed-Bid Auction with EPR Pairs

Recently, an experimentally feasible three-party quantum sealed-bid auction protocol based on EPR pairs [Z.Y. Wang, Commun. Theor. Phys. 54 （2010） 997] was proposed. However, this study points out Wang＇s protocol cannot resist some internal bidders＇ attacks, such as the Twiee-CNOT attack, the collusion attack. A malicious bidder can launch the Twice-CNOT attack to obtain the other＇s bid, or the dishonest auctioneer may collude with one bidder and help him/her win the action by changing his/her bid. For preventing against these attacks, a simple solution by using the QKD-based message encryption and a post-confirmation mechanism by adopting the hash function are proposed.     

缘线匹配对非定常流动影响初探

为深化缘线匹配对叶轮机非定常流动影响的认识,本文以关注尾迹撞击叶表展向轨迹为出发点,围绕缘线匹配对叶轮机非定常流动及性能影响进行了初步数值探索.研究表明:不同缘线匹配时叶片整体性能参数具有不同的脉动水平;给定缘线匹配下,整体性能参数脉动幅值随工况几乎不变或变化很缓;在设计点为达到降低某种脉动目的而实施的缘线匹配在非设计点同样有效;尽管微弱,数值模拟中还发现缘线匹配对上游尾迹随流掺混产生影响;缘线匹配严重影响时均相关项量值水平,尤其在叶尖、叶根和前缘附近.     

Numerical Analysis of Electromagnetic Fields in Multiscale Model

Modeling technique for electromagnetic fields excited by antennas is an important topic in computational electromagnetics, which is concerned with the numerical solution of Maxwell's equations. In this paper, a novel hybrid technique that combines method of moments(MoM) with finite-difference time-domain(FDTD) method is presented to handle the problem. This approach employed Huygen's principle to realize the hybridization of the two classical numerical algorithms. For wideband electromagnetic data, the interpolation scheme is used in the MoM based on the dyadic Green's function. On the other hand, with the help of equivalence principle, the scattered electric and magnetic fields on the Huygen's surface calculated by MoM are taken as the sources for FDTD. Therefore, the electromagnetic fields in the environment can be obtained by employing finite-difference time-domain method. Finally, numerical results show the validity of the proposed technique by analyzing two canonical samples.     

HL-2A 装置超声分子束注入缓解偏滤器靶板上边缘局域模热通量研究

在HL-2A 装置上优化和发展了偏滤器靶板上的红外测温系统,并利用该系统分析了高约束模放电期间边缘局域模的热沉积分布特性。在高约束模式放电期间,超声分子束注入使边缘局域模所引起的偏滤器靶板上瞬间热通量峰值下降了~60%,并伴随着边缘局域模爆发频率增加了2~3 倍,而等离子体储能仅下降了~8%。分析结果表明,大幅度的丝状结构在超声分子束注入之后得到了有效抑制,沉积到偏滤器靶板上的瞬间热通量峰值也随之下降。此外,在超声分子束注入之后偏滤器室内的热辐射损失大幅度增加,从而耗散了热输运所携带的部分能量,进一步分散了沉积到偏滤器靶板上的能量,有效地保护了偏滤器靶板。     

NO2分子(A)2B2电子激发态荧光辐射寿命的实验研究

采用准分子激光泵浦的染料激光诱导的高分辨荧光技术,测定了NO2分子2B2电子激发态的荧光辐射寿命及其与激发波长、NO2分子气体压力之间的关系,结果表明荧光衰减曲线是单指数的,辐射寿命在20.44～72.53 μs之间变化,利用光谱涨落统计理论对(A)2B2电子态的反常长寿命进行了讨论.     

Lamb wave sensors array for nonviscous liquid sensing

The interdigital transducer (IDT) can excite Lamb wave in a piezoelectric plate loading with a liquid layer, and the phase velocity of Lamb wave is associated with the properties of the liquid layer. In this paper, the concept of effective permittivity is introduced to study the Lamb wave’s potential application in liquid sensing. Considering the measuring of ideal nonviscous liquid, the sensors array is designed to sense the density and the dielectric constant of the liquid layer simultaneously. Using LiNbO₃ as piezoelectric material, in order to improve the sensors array sensitivity and the electro-mechanical coupling coefficient, the optimized results including plate thicknesses and cut orientations are presented by numerical simulation. These studies show that the Lamb wave sensors array can be potential in liquid sensing.     

YBCO涂层导体用Ni5W基带的制备和立方织构的发展

为了制作能满足YBCO涂层导体(coated conductor)所需要的高强度、低磁性的立方织构基带,本工作用粉末冶金方法制作了Ni-5at%W合金基带.为评估基带中立方织构的发展,用March-Dollase函数对各种热处理样品的择优取向度进行了研究,结果与用X射线极图法和电子背散射衍射法得到的结果基本一致.研究结果表明,在实验中所用的工艺参数范围内,随总加工率和热处理温度的提高,基带中立方织构百分数明显增高.提高总加工率实际增加了冷加工样品中立方织构晶粒或立方核心的数量.实验中得到了较好的和实用的工艺制度,用这种工艺可以制作出具有99%～100%立方织构百分数,并具有很好一致取向度的Ni5W基带.     

Memory Effect in Ceramic Superconductors

We measured the time decay of the magnetic moment of high T_c superconductors YBa₂Cu₃O_7-δ ceramic samples and found the memory effect which has hitherto been reported only in single crystals. The temperature and field ranges, especially the memory phenomenon in ceramic samples at liquid nitrogen temperature can only be understood in a combined picture of both flux creep and glass behaviour     

用正电子湮没技术研究纯镍多晶体疲劳过程中的晶体缺陷

对充分退火纯镍多晶体样品分组进行了恒应变幅拉-压疲劳试验和冷轧形变后,测量了正电子湮没参数;并选少数疲劳试样进行了电子显微镜薄膜衍射象观察。用多指数拟合方法从疲劳试样的正电子湮没寿命谱中分解出与正电子在小空位团中湮没相应的成份。这些寿命值在不同疲劳阶段分别平均为209,255和>300ps。其相对强度的变化与小空位团浓度增加然后尺寸增大的趋势相符合。从而,本文根据正电子湮没技术提供了纯镍多晶体疲劳过程中除大量位错外空位聚集的实验证据。利用简单三态正电子捕获模型估算了上述缺陷浓度。本工作还提供了用多指数拟合方法分解复杂寿命谱和用于简单三态捕获模型的例证。 关键词：