开普勒第二定律的建立

 约翰·开普勒(ＪｏｈａｎｎｅｓＫｅｐｌｅｒ,1571-1630)是德国著名的天文学家和物理学家,一生在多方面对科学的发展做出了贡献,尤其在天文学领域,他经过多年的努力探索,建立了开普勒三定律,从而使人们对行星的运动有了更加明确清晰的认识,也为牛顿发现万有引力定律奠定了基础。正是由于这一卓越的科学成就,开普勒被后人称为“天空的立法者”。本文就他建立开普勒第二定律的过程做一探讨。1.第谷与开普勒的合作科学的发展不仅需要理论,而且不能离开观察实验。在科学向前发展的过程中,有时理论这只脚向前先迈一步,有时观察实验这只脚向前先迈一步。     

Influence of Yb-Doped Nanoporous TiO2 Films on Photovoltaic Performance of Dye-Sensitized Solar Cells

Yb-doped TiO2 pastes with different Yb/TiO2 weight ratios are prepared in the sol-gel process to obtain dyesensitized solar cells （DSCs）. The nanocrystalline size of Yb-TiO2 becomes smaller and the lattice parameters change. Lattice distortion is observed and dark current is detected. It is found that a part of Yb existing as insulating oxide Yb2O3 state acts as barrier layers at the electrode-electrolyte interface to suppress charge recombination. A Yb-doped TiO2 electrode applied in DSCs leads to a higher open-circuit voltage and a higher fill factor. How the Yb-doped TiO2 films affect the photovoltaic response of DSCs is discussed.     

使用超声估计肌肉疲劳的初步研究

表面肌电信号把神经肌肉活动和肌肉收缩联系起来，已被视为一种估计肌肉疲劳比较客观的方法，但也存在一些不足。另一方面，超声已广泛应用于医学诊断和研究，在骨骼肌方面也有不少研究报道，但还未见文献报道超声用于肌肉疲劳的估计。本文介绍一套自行开发的新的同步连续采集B超图像、力矩和肌电信号的采集系统，并利用它对肱二头肌的肌肉疲劳进行了估计。试验表明在30秒的肌肉疲劳过程中，肌肉厚度会以非线性的方式增加。     

Application of Electron-Shelving Detection via 423 nm Transition in Calcium-Beam Optical Frequency Standard

A new scheme of small compact optical frequency standard based on thermal calcium beam with application of 423 nm shelving detection and sharp-angle velocity selection detection is proposed. Combining these presented techniques, we conclude that a small compact optical frequency standard based on thermal calcium beam will outperform the commercial caesium-beam microwave dock, like the 5071 Cs clock （from Hp to Agilent, now Symmetricom company）, both in accuracy and stability.     

用HZSM-5催化剂直接合成对甲乙苯的研究

本文用适当处理的HZSM-5催化剂进行甲苯乙烯烃化直接合成对甲乙苯,该催化剂经 过 200小时的长运转试验表明具有良好反应性能。还探讨了 HZSM-5沸石催化剂的表面酸 性质及微孔有效扩散系数与其择形催化的关系。 1.实验部分 1.1 催化剂制备 由本实验室用氨水合成的 ZSM-5与粘结剂 Al2O3混合成型,经硝酸铵溶液交换,制得 HZSM-5催化剂,再经适当处理制得五种不同性能的 HZSM-5催化 剂。 1.2 烷基化反应 该反应是在常压小型固定床积分反应器中进行,以甲苯转化率CT(mol%)表示催化剂活性;以产物中对甲乙苯与甲乙苯总和之比Sp(%)表示对位选…     

Effect of Nonradiative Recombination on Carrier Dynamics in GaInNAs/GaAs Quantum Wells

The nonradiative recombination effect on carrier dynamics in GalnNAs/GaAs quantum wells is studied by timeresolved photoluminescence （TRPL） and polarization-dependent TRPL at various excitation intensities. It is found that both recombination dynamics and spin relaxation dynamics strongly depend on the excitation intensity. Under moderate excitation intensities the PL decay curves exhibit unusual non-exponential behaviour. This result is well simulated by a rate equation involving both the radiative and non-radiative recombinations via the introduction of a new parameter of the effective concentration of nonradiative recombination centres in the rate equation. In the spin dynamics study, the spin relaxation also shows strong excitation power dependence. Under the high excitation power an increase of spin polarization degree with time is observed. This new finding provides a useful hint that the spin process can be controlled by excitation power in GaInNAs systems.     

Single Qubit and Its Universal Logic Gate Made of a Heisenberg Spin Cluster with Five Particles

We investigate an anisotropic Heisenberg spin cluster with five particles controlled by a time-dependent magnetic field. With the algebraic dynamical method, we obtain the exact analytical solution to the time dependent Schr6dinger equation. Based on the analytical solution, it is shown that the system can be used as a universal single qubit logic gate controlled by the strength and frequency of the magnetic field, and the six special single qubit logic gates can be realized physically. We also discuss the anti-decoherence property of the qubit and its logic gates resulted from particle coupling effect and collectivity of the cluster.     

纳米技术在武器系统中的应用及发展趋势

技术革命在带来产业革命的同时,也必将引起军事领域的重大变革。美国认为纳米科技是国防工业的未来,世界上各主要军事大国,也都投入大量经费,开展研制试验、制造纳米武器。作为军事信息技术重要基础的军用微电子技术,如果一旦得到纳米技术的支撑,将促使以微电子技术为代表的当代信息技术实现向以纳米技术和分子器件为代表的智能信息技术的巨大转变。纳米电子技术对未来军事作战领域     

多维测量结果不确定度评价方法初探

为解决以多维矢量形式存在被测对象的测量质量评定问题,该文应用测量不确定度理论和多元概率统计方法,将测量不确定度理论进行了向多维的拓展;对多维情况下的测量不确定度传播律进行了推导;论述了多维不确定度的表示方法及空间几何意义;提出了以多维不确定度比较不同测量结果质量的方法;并给出了常用多维测量方法,如等精度独立多维测量和不等精度独立多维测量的不确定度评定方法。理论分析及仿真算例表明,所提出的理论具有较完备的体系,能够满足测量实际中常用多维测量方法的不确定度评定需求。