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981.
A Monte Carlo code “1DHET” has been utilized for simulating the transport of neutral helium near divertor flat pumping target plate. The dominant atomic processes of electron impact ionization and elastic scattering by plasma ions are included. The thermal and streaming motion of the ions along the magnetic field is taken into consideration. Calculations show that the probability of neutral helium turning back to the target plate will increase by 45% if the divertor edge plasma density is smoothly raised up to 4.7 times higher at the divertor plate than that at 7cm apart inward as compared with the ordinary outward decreasing density profile while keeping temperature profile fixed. The temperature decreases smoothly from 40 eV at z = 7 cm to 3 eV at the plate. The effects of angle between the magnetic field and the target plate, the temperature of plate, edge plasma sheath potential and different target materials on the probability of helium particles scattered back to the plate are studied. 相似文献
982.
邓冠铁 《数学物理学报(A辑)》2006,26(1):45-048
对在半平面中属于加权Hardy空间,不恒为零且在某一固定点列上为零的解析函数的存在性给出了充分必要条件。 相似文献
983.
984.
Cr^4+:YAG的可饱和吸收特性与被动Q开关性能研究 总被引:22,自引:6,他引:16
运用速率方程计算了Cr^4+:YAG晶体的可饱和吸收特性参数,包括初始吸收系数,饱和吸收系数,饱和光强和损耗调制度,用Cr^4+:YAG对脉冲和连续Nd:YAG激光器进行了被动调Q,在脉冲Nd:YAG激光器上得到了8ns的调Q激光脉冲,在连续Nd:YAG激光器的调Q中得到了间隔和幅度抖动小于5%的输出脉冲充列。 相似文献
985.
艾纳香中黄酮化合物的研究 总被引:7,自引:1,他引:6
从中药艾纳香(Blumea balsamifera DC)中分离得到两种新的黄酮化合物,应用NMR、MS、IR、UV等波谱数据,确定其化学结构为3,5,3'-三羟基-7,4'-二甲氧基黄酮(Ⅰ)和3,5,3',4'-四羟基-7-甲氧基黄酮(Ⅱ). 相似文献
986.
本文讨论非线性方程组的算法的局部收敛性,给出了一个统一的收敛定理.该定理相当一般,不仅包含ABS型方程,而且对目前常用的许多方法也都适用. 相似文献
987.
Certificateless signature: a new security model and an improved generic construction 总被引:2,自引:0,他引:2
Bessie C. Hu Duncan S. Wong Zhenfeng Zhang Xiaotie Deng 《Designs, Codes and Cryptography》2007,42(2):109-126
Certificateless cryptography involves a Key Generation Center (KGC) which issues a partial key to a user and the user also
independently generates an additional public/secret key pair in such a way that the KGC who knows only the partial key but
not the additional secret key is not able to do any cryptographic operation on behalf of the user; and a third party who replaces
the public/secret key pair but does not know the partial key cannot do any cryptographic operation as the user either. We
call this attack launched by the third party as the key replacement attack. In ACISP 2004, Yum and Lee proposed a generic
construction of digital signature schemes under the framework of certificateless cryptography. In this paper, we show that
their generic construction is insecure against key replacement attack. In particular, we give some concrete examples to show
that the security requirements of some building blocks they specified are insufficient to support some of their security claims.
We then propose a modification of their scheme and show its security in a new and simplified security model. We show that
our simplified definition and adversarial model not only capture all the distinct features of certificateless signature but
are also more versatile when compared with all the comparable ones. We believe that the model itself is of independent interest.A
conventional certificateless signature scheme only achieves Girault’s Level 2 security. For achieving Level 3 security, that
a conventional signature scheme in Public Key Infrastructure does, we propose an extension to our definition of certificateless
signature scheme and introduce an additional security model for this extension. We show that our generic construction satisfies
Level 3 security after some appropriate and simple modification.
A preliminary version of the extended abstract of partial results appeared in ACISP 2006 [9]. 相似文献
988.
989.
Q.Y. Zhang Z.M. Yang G.F. Yang Z.D. Deng Z.H. Jiang 《Journal of Physics and Chemistry of Solids》2005,66(7):1281-1286
We report on the blue-green-red up-conversion spectroscopic properties of Pr3+/Yb3+-codoped oxyhalide tellurite glasses upon excitation of a conventional 980 nm laser diode (LD). Significant enhancement of the blue-green-red up-conversion emission intensity has been observed with increasing PbCl2 doping. The up-conversion intensity has a quadratic dependence on incident pump laser power, indicating a two-photon process. The population of the Pr3+ upper 3P0 emitting level was accomplished through a combination of a ground state absorption, energy transfer and excitated state absorption. 1.3-μm emission in the second telecom window originated from Pr3+:1G4→3H5 transition has also been investigated upon excitation at 980 nm LD. The measured peak wavelength and full width at half-maximum of the fluorescent are 1335 nm and ∼100 nm, respectively. An enhanced 1.3μm emission with increasing PbCl2 doping has also been observed. Codoping of Yb3+ significantly enhance both the blue-green-red up-conversion emission and 1.3-μm emission intensity by way of a nonradiative Yb3+:2F5→Pr3+:1G4 energy transfer. 相似文献
990.
Using second-order autocorrelation conception, a novel method and instrument for accurately measuring interval between two linearly polarized ultrashort pulses with real time were presented. The experiment demonstrated that the measuring method and instrument were simple and accurate (the measurement error < 5 fs). During measuring, there was no moving element resulting in dynamic measurement error. 相似文献