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71.
SUMMARY An apparatus for the accurate determination of reaction kinetics by the stirred flow technique is described. A 2- to 3-ml stirred reactor is fed by solutions injected from screw-driven syringes. The flow rates vary between 8 × 10-4 and 58 ml/min and are controlled to ±0.1%. The pH is determined directly from an electrode inserted into the reactor cell. An auxiliary unit for continuous variation of concentration over a specified range is provided. The progress of the reaction is followed by direct spectro-photometric observation and other techniques. The stirred flow reactor is particularly useful for complex reactions and for the detection of short-lived intermediates. It should find use for the study of enzyme kinetics. 相似文献
72.
板坯结晶器与振动台振动特征分析 总被引:3,自引:0,他引:3
应用自行开发的软硬件系统,对板坯连铸机结晶器及振动台进行测试与分析,发现其振动特征随拉速而变化的规律,提出了用相位分析判定振型的方法。 相似文献
73.
X. B. Li T. S. Lok J. Zhao P. J. Zhao 《International Journal of Rock Mechanics and Mining Sciences》2000,37(7)
This paper highlights an improved experimental approach for eliminating oscillation that exists in the dynamic stress–strain response of rocks and other brittle materials obtained from tests using a split Hopkinson pressure bar (SHPB). Both analytical and experimental results for a number of rock types are presented to verify the idea. Results from the investigation indicate that oscillation in the dynamic stress–strain response of these materials originates from the Pochhammer–Chree dispersion of the loading incident wave, and more evidently from the relatively low strength and elastic modulus of the samples compared with metallic materials. In order to control the oscillation effectively, it is proposed that a half-sine loading waveform should be used instead of the conventional rectangular loading waveform in SHPB tests. Experimental results obtained from both the conventional and the improved methods are presented, including dynamic complete stress–strain curves for granite, sandstone and limestone. The improved method eliminates oscillation in the tests, provides better stability of strain rate and more representative results than those obtained from the conventional rectangular loading waveform shape. 相似文献
74.
75.
振动拉伸的弹粘塑性模型 总被引:6,自引:0,他引:6
基于弹粘塑性本构关系 ,讨论了附加振动时单轴拉伸的应变及应力变化过程。分析结果表明 ,本文所给出的力学模型 ,再现了振动拉伸过程中的应力超调及平均应力降低等现象 相似文献
76.
随着弹道导弹技术的发展,中段机动变轨需要进行高精度的姿态指向、快速的大角度机动以及有效地节省能量等复杂的姿态控制。该文将自适应变结构控制应用于弹道导弹中段姿态控制中,推导了滑模到达条件,设计了相应形式的切换函数,给出了一种参数选择方案井设计了一种控制器以抑制抖振,给出了详尽的实现方法。仿真结果表明,该方法可以很好地实现中段姿态控制。具有良好的应用意义。 相似文献
77.
本文对原PIN半导体探测器信号引出线结构线路进行了分析,为了消除小灵敏面积PIN探测器振荡现象,把原信号引出线结构改进成微带结构,并对改进后的探测器时间响应性能和线性电流进行了实验测量。 相似文献
78.
The stoichiometry of chemical oscillation systems, especially that of the Oregonator proposed by Field and Noyes (1974), is discussed with use of the generalized stoichiometric number theory by Horiuti and Nakamura (1957). The independent stoichiometric equations derived by Noyes (1976) are shown to correspond to Horiuti and Nakamura's reaction routes, each of which was expressed in terms of a set of stoichiometric numbers. It is found that the relations derived by Noyes are partly incorrect. 相似文献
79.
Jianchu Jiang Xiaoping Li Xianhua Tang 《Computers & Mathematics with Applications》2004,47(12):1875-1884
In this paper, some new oscillation criteria are obtained for the first-order delay difference equation , where k,l1,l2,, ls are positive integer numbers, f is a function. Our results improve the known results in the literature. And some examples are given to demonstrate the advantage of our results. 相似文献
80.
Abstract In this study, the effects of the El Niño-Southern Oscillation (ENSO) on the rainfall variability in the central (Savannah) and southern (Equatorial) regions of Sudan are examined. The annual rainfall data from 12 rainfall stations for 49 years are used in this examination. The results of the study show that the areal annual regionally averaged rainfall values in the two regions have decreased markedly since the early 1960s, with co-existence between the driest years and the warm ENSO events. The correlation between the annual regional rainfall values and the ENSO events is found to be relatively higher for the Savannah region than for the Equatorial region. Two regional ENSO-rainfall prediction models are developed, one for each region. These models use the ENSO sea surface temperature. The results of the models test show that both models can significantly improve the predictability of the annual rainfall values, which is essential for the planning and the management of water resources in Sudan 相似文献