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101.
Kortunov P Vasenkov S Kärger J Fé Elía M Perez M Stöcker M Papadopoulos GK Theodorou D Drescher B McElhiney G Bernauer B Krystl V Kocirik M Zikanova A Jirglova H Berger C Gläser R Weitkamp J Hansen EW 《Magnetic resonance imaging》2005,23(2):233-237
Pulsed-field gradient nuclear magnetic resonance (PFG NMR) has been applied to study molecular diffusion in industrial fluid catalytic cracking (FCC) catalysts and in USY zeolite for a broad range of molecular displacements and temperatures. The results of this study have been used to elucidate the relevance of molecular transport on various displacements for the rate of molecular exchange between catalyst particles and their surroundings. It turned out that this rate, which may determine the overall rate and selectivity of FCC process, is primarily related to the diffusion mode associated with displacements larger than the size of zeolite crystals located in the particles but smaller than the size of the particles. This conclusion has been confirmed by comparative studies of the catalytic performance of different FCC catalysts. 相似文献
102.
We report a wide-field fluorescence lifetime imaging microscope based on a low-repetition-rate (3.7-MHz) passively mode-locked diode-pumped laser source. This inexpensive and compact laser source operating in the visible and UV range can excite a wide range of fluorophores of biological interest. We demonstrate that the power of this laser source is highly sufficient for studying biological systems with low quantum yields (autofluorescence of tissues and stained living cells). The maximum measurable lifetime is also strongly increased with this laser source, as fluorescence intensity measurement can occur 250 ns after the excitation pulse. 相似文献
103.
Papadopoulos DN Forget S Delaigue M Druon F Balembois F Georges P 《Optics letters》2003,28(19):1838-1840
We demonstrate the operation of an ultralow-repetition-rate, high-peak-power, picosecond diode-pumped Nd:YVO4 passively mode-locked laser oscillator. Repetition rates lower than 1 MHz were achieved with the use of a new design for a multiple-pass cavity and a semiconductor saturable absorber. Long-term stable operation at 1.2 MHz with a pulse duration of 16.3 ps and an average output power of 470 mW, corresponding to 24-kW peak-power pulses, is reported. These are to our knowledge the lowest-repetition-rate high-peak-power pulses ever generated directly from apicosecond laser resonator without cavity dumping. 相似文献
104.
Richard E. Crandall Ernst W. Mayer Jason S. Papadopoulos. 《Mathematics of Computation》2003,72(243):1555-1572
We have shown by machine proof that is composite. The rigorous Pépin primality test was performed using independently developed programs running simultaneously on two different, physically separated processors. Each program employed a floating-point, FFT-based discrete weighted transform (DWT) to effect multiplication modulo . The final, respective Pépin residues obtained by these two machines were in complete agreement. Using intermediate residues stored periodically during one of the floating-point runs, a separate algorithm for pure-integer negacyclic convolution verified the result in a ``wavefront' paradigm, by running simultaneously on numerous additional machines, to effect piecewise verification of a saturating set of deterministic links for the Pépin chain. We deposited a final Pépin residue for possible use by future investigators in the event that a proper factor of should be discovered; herein we report the more compact, traditional Selfridge-Hurwitz residues. For the sake of completeness, we also generated a Pépin residue for , and via the Suyama test determined that the known cofactor of this number is composite.
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基于PIC方法的二维束流动力学模拟程序及其初步应用 总被引:1,自引:0,他引:1
为了深入研究强流负氢束在强流质子回旋加速器CYCIAE-100轴向注入线中的传输, 利用split-operator方法分解外场和束流自身的空间电荷场的作用. 对外
场利用单粒子跟踪技术, 采用一阶线性近似; 对空间电荷场采用PIC方法, 利用
快速傅里叶变换求解Poisson方程. 用FORTRAN95语言开发了一个基于面向对象技术的二维宏粒子传输计算程序CYCPIC2D, 本程序可以计算任意分布的强流束在输运线上的传输.最后给出了对CYCIAE-100注入线的模拟计算结果, 并和程序ORBIT, TRACE 3-D的结果进行比对验证, 结果表明: 空间电荷效应在此注入线上有较大的影响, 而且3个程序计算的不同中性化的结果基本上一致; 束流强度达到几十毫安时, 基于PIC方法的两个程序CYCPIC2D和ORBIT的计算结果完全吻合, 而线性近似程序TRACE 3-D有明显差异. 相似文献
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109.
Nylon I I is a high-performance semicrystalline polymer which was used widely in manyfields. In recent years, the curious ferroelectric and piezoelectric propel'ties of nylon I Iwere foundl'2. It is well known that piezoelectricity is related to the crystal form ofNylon I 1.The sample was mounteds in a capillary (diameter was Zmm) within a small ovenwith mica windows. The scattered intensity was recorded from Q = 0.2 to 6.5 A-] (Q =ursine/~) using steps of AQ=o.o5A-'. The values of the p… 相似文献
110.