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通过比较各种软件无线电结构的优缺点,针对既具有交换网络结构又具有分层结构优点的基于交换网络的分层无线电结构方案,提出了部分改进思想。 相似文献
3.
Broadline nuclear magnetic resonance measurements have been carried out for the proton resonance in oriented poly(vinylidene fluoride). The spectra in general show two component lines with distinctly different line widths. The broad component shows a high degree of molecular orientation and can be satisfactorily assigned to the crystalline regions of the polymer. The narrow component corresponds to an oriented non crystalline phase which is sufficiently constrained to allow motion about the chain axis only. An appreciable decrease in the value of the rigid mass fraction was observed in both of the samples over the temperature range examined. Our calculations indicate that this could play an important role in the temperature dependence of the pyroelectric response of this material. 相似文献
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Wladek T. Sobol L.John SchreinerLjubis̆a Miljković Maria E. Marcondes-HeleneLeonard W. Reeves M.Mik Pintar 《Fuel》1985
The first results of the analysis of bitumen and oil sands using the recently developed n.m.r. spingrouping technique are presented. The n.m.r. relaxation experiments were carried out on bitumen, and on natural and dried oil sands samples. The results indicate that the spin-grouping can resolve and quantify several components of the samples studied. The bitumen and bitumen fraction of the oil sands are resolved according to their spin-spin relaxation times into three major groups: solid-like (rigid), solid-like (mobile) and semi-liquid. The water in the oil sands exists in two different environments. Tentatively one environment is assigned to be the bridges between the sand grains, while the other is assigned to be the clay surface. One can conclude that with spin grouping of complex mixtures the decomposition (in which components are resolved according to their dynamic state) is possible. The accuracy of such resolution is of the order of a few per cent. 相似文献
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由于在机器人导航等领域新的图像装置不符合透视规则,无法运用传统的透视位置估计方法,采用吴氏零点分解方法,给出非透视3点问题的解析解.利用新图像装置的几何条件,建立了非透视3点方程系统. 相似文献
8.
Methyl groups from chain scission and H-crosslinks have been identified by solid-state nuclear magnetic resonance in amorphous ethylene-propylene copolymers containing 23 and 36 mole % propylene after γ-irradiation to 10 MGy at 30°C. G (scission) and G (crosslink) values determined from the n.m.r. spectra and by extraction are in agreement, which suggests that the crosslinks are not clustered. This may differ from the situation in polyethylene where there is a substantial crystalline content. G(S). G(X) and the ratio G(S)/G(X) increase with increasing propylene content of the copolymers. 相似文献
9.
Masashi Morishita 《Journal of Low Temperature Physics》2007,148(5-6):761-765
Heat capacities of a submonolayer 3He solid film adsorbed on a graphite surface are measured in magnetic fields up to 400 Oe. The measured heat capacity shifts
to higher temperatures with an increasing magnetic field. The amplitudes of the shifts are twenty times larger than the magnitude
of the Zeeman energy, which is anomalously large. With regard to the origin of these large shifts, the reduction of frustrations
and the weakening of the competition between multiple spin exchange interactions are discussed. 相似文献
10.
Wei Hua Wang 《Progress in Materials Science》2007,52(4):540-596
Bulk metallic glasses (BMGs) are of current interest worldwide in materials science and engineering because of their unique properties. Exploring BMGs materials becomes one of the hottest topics in the materials science field. To date, there is very active worldwide development of new BMGs, and extensive efforts have been carried out to understand and improve the glass-forming ability of metallic materials supported by large government and industry programs in North America, Asia, and Europe. Minor addition or microalloying technique, which has been widely used in other metallurgical fields, plays effective and important roles in formation, crystallization, thermal stability and property improvement of BMGs. This simple approach provides a powerful tool for the BMG-forming alloys development and design. In this paper, we present a comprehensive review of the history and the recent developments of this technique in the field of BMGs. The roles of the minor addition in the formation and the properties of the BMGs and the BMG-based composites will be discussed and summarized within the framework of thermodynamics, kinetics and microstructure. The empirical criteria, or the principles and guidelines for the applications of the technique in BMG field are outlined. 相似文献