男子纵跳马屈腿腾越速成训练法初探

对男子纵跳马屈腿腾越,根据训练规律,安排了具体解决素质、技术和胆量的三大要素的选择性训练。通过理论分析和实践证明,过马的关键技术是快速的助跑并采用制动式的抢板;起跳后不要立即扶马,而要延伸一段时间,使人体重心向前上方形成抛物线。通过跳高垫使练习者在没有思想压力的情况下,建立一整套与跳马屈腿腾越相应的新的动力定型,为完成跳马动作创造有利条件。     

浅析公路桥头跳车原因与解决措施

从地基土质、台背填料压缩、刚柔突变几方面分析了桥头跳车产生的原因，并从地基处理、路基处理、路面处理三方面提出了解决桥头跳车的措施，以确保行车顺畅，保证行车安全性。     

粉喷桩处理桥头跳车影响因素分析及控制

通过工程实例分析了粉喷桩处理桥头跳车的影响因素,主要包括有粉喷桩的强度、置换率、桩底持力层、地基土含水量、施工工艺和搅拌机钻头的选择等,并提出相应的控制措施。     

An algorithm to solve transient structural non-linear problems for non-matching time-space domains

This paper presents a new transient algorithm to couple sub-domains having non-matching time and space interfaces. The time integrators in each of the sub-domains are of the Newmark family but can be different. The method is also developed for non-linear explicit transient computations for which the time steps are not constant. A number of examples are presented which illustrate the interest, quality and the efficiency of the proposed method.     

A new approach to the mechanism of chlorine evolution: Separate examination of the kinetic steps using ac impedance on a rotating thin ring electrode

In the absence of a bulk diffusion effect, it is shown for the first time that the impedance spectra for the chlorine evolution reaction on a rotating thin ring electrode comprise three consecutive semicircles in the capacitive half of the complex plane. The first (highest frequency) semicircle is due to the charge-transfer resistance for chloride discharge and the simultaneous chlorine adsorption coupled to the double-layer capacitance. The second semicircle (around 5 Hz) is due to the adsorption and desorption of a chlorine intermediate. The third (lowest frequency, around 0.5 Hz) semicircle is due to the relaxation of surface oxygen species. The impedance data allow the steps of the overall reaction to be examined individually. On a Pt surface the rate of chloride discharge and simultaneous chlorine adsorption (the admittance of the first semicircle) is first order with respect to chloride concentration and has a potential-dependence close to 58 mV/decade. The rate of the adsorption and desorption process (the admittance of the second semicircle) is second order with respect to chloride concentration, and has a potential dependence close to 30 mV/decade. The time constant for the adsorption/desorption processes is ca 20 ms, independent of electrode potential in the range studied. These features are consistent with a mechanism in which a faster discharge reaction (Cl⁻ Cl_ad + e) is followed by a slower surface combination reaction (2Cl_ad → Cl₂), but inconsistent with mechanisms in which ion + atom desorption is predominant, the initial chloride discharge is slow, or a unipositively charged chlorine species is involved.     

Formation of uniform GaAs multi-atomic steps with 20–30 nm periodicity and related structures on vicinal (111)B planes by MBE

We studied morphology of GaAs surfaces and the transport properties of two-dimensional electron gas (2DEG) on vicinal (111)B planes. Multi-atomic steps (MASs) are found on the vicinal (111)B facet grown by molecular beam epitaxy, which will affect electron transport on the facet. We also studied how the morphology of GaAs epilayers on vicinal (111)B substrates depends on growth conditions, especially on the As₄ flux. The uniformity of MASs on the substrates have been improved and smooth surfaces were obtained when the GaAs was grown with high As₄ flux, providing step periodicity of 20 nm. The channel resistance of the 2DEG perpendicular to the MASs is reduced drastically with this smooth morphology. These findings are valuable not only for fabricating quantum devices on the (111)B facets but also those on the vicinal (111)B substrates.     

用正交设计法优化导叶分段关闭规律的参数

本文介绍了正交设计法优化水轮机导叶分段关闭规律参数的方法，实例表明，此方法具有简单，准确和直观的优点。     

低温电流比较仪动态特性的研究

低温电流比较仪是现代电测量技术中最为准确的比例量具，在传递量子化霍尔电阻基准的量值时发挥了独特的作用。为了进一步提高CCC的比例准确度，一个有效的方法是采用匝数较多的绕组。但国际上各实验室均遇到了绕组匝数较高时电流会发生跳跃的困难，目前未见到对此问题进行分析及提出解决办法的文章。本文对CCC系统的动态特性进行了分析，找到了产生该现象的原因，并采取措施改进了系统的动态特性，避免了跳跃现象。与国际上的同类装置相比，CCC的绕组匝数被提高了8倍，信噪比及比例准确度也有了很大的提高。结合其他措施，完成了综合不确定度为10^-10量级的量子化霍尔电阻标准装置。     

Imaging applications of synchrotron X-ray phase-contrast microtomography in biological morphology and biomaterials science. I. General aspects of the technique and its advantages in the analysis of millimetre-sized arthropod structure

Synchrotron‐generated X‐rays provide scientists with a multitude of investigative techniques well suited for the analysis of the composition and structure of all types of materials and specimens. Here, we describe the properties of synchrotron‐generated X‐rays and the advantages that they provide for qualitative morphological research of millimetre‐sized biological organisms and biomaterials. Case studies of the anatomy of insect heads, of whole microarthropods and of the three‐dimensional reconstruction of the cuticular tendons of jumping beetles, all performed at the beamline ID19 of the European Synchrotron Radiation Facility (ESRF), are presented to illustrate the techniques of phase‐contrast tomography available for anatomical and structural investigations. Various sample preparation techniques are described and compared and experimental settings that we have found to be particularly successful are given. On comparing the strengths and weaknesses of the technique with traditional histological thin sectioning, we conclude that synchrotron radiation microtomography has a great potential in biological microanatomy.     

浅谈浮法玻璃熔窑的节能技术

对浮法玻璃熔窑节能技术进行了探讨,特别就熔窑运行过程中实际操作方面的一些节能技术进行了分析总结,并提出了自己的见解.