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91.
92.
我国的液体闪烁探测技术 总被引:1,自引:0,他引:1
江丕栋 《核电子学与探测技术》1990,10(5):315-320,F003
本文介绍了液体闪烁探测技术在中国的发展过程,在仪器、元件的研制和生产、测量及制样方法,以及绝对测量和标准化等方面所取得的成就。介绍了学术活动情况。概述了液闪技术在我国各个领域中的应用。 相似文献
93.
本文从效率示踪源淬灭水平,化学、颜色猝灭成分以及增益选择等方面对效率示踪法作了改进的探讨,适当猝灭且有较高增益会给出更小的校正误差,谱形校正是改进效率示踪法的一个根本途径。 相似文献
94.
Ian Foster 《International journal of parallel programming》1989,18(3):181-203
An asynchronous garbage collector for a message-passing multiprocessor (multicomputer) is described. This combines Weighted Reference Counting (WRC) interprocessor collection and tracing intraprocessor collection to permit individual processors to reclaim local storage independently. A novel feature is the integration of Weighted Reference Counting collection and the communication algorithms required to support a global address space in a single assignment language. This significantly reduces communication overhead and space requirements attributable to garbage collection. In addition, techniques are described that avoid the creation of cyclic structures that cannot be reclaimed using WRC. Experimental studies performed in a concurrent logic programming system that incorporates the collector confirm its efficiency and the benefits of integrating garbage collector and language implementation. 相似文献
95.
为提高大肠菌群和菌落总数的计数效率,选用2-硝基苯基-β-D-吡喃半乳糖苷作为平板培养基中的显色底物,利用大肠菌群lacZ基因编码的β-半乳糖苷酶将其分解产生黄色化合物,使得大肠菌群菌落区分于其他菌株,实现大肠菌群和菌落总数的同时计数,优化该培养基配方,评估培养基的特异性、准确性以及在生乳中的应用效果。最终确定该培养基配方:胰蛋白胨12.5 g/L、酵母浸粉2.5 g/L、磷酸氢二钾2.75 g/L、磷酸二氢钾1.75 g/L、氯化钠5.0 g/L、琼脂15.0 g/L,2-硝基苯基-β-D-吡喃半乳糖苷0.1 g/L,pH值为7.0。在此基础上,添加0.05 g/L异丙基-β-D-硫代半乳糖苷或2.0 g/L乳糖均能够增强菌落显色效果,而葡萄糖则会抑制黄色化合物生成。特异性实验中,仅大肠菌群菌落颜色呈黄橙色,其他菌株则呈乳白色。在生乳样本中,该培养基与国标方法对于大肠菌群和菌落总数的计数结果基本一致。因此,该复合显色培养基能够大大提高大肠菌群和菌落总数的计数效率,降低检测成本,为生乳的卫生指标检测提供一种可行方案。 相似文献
96.
A standardized methodology for the fractal analysis of histological sections of trabecular bone has been established.
A modified box counting method has been developed for use on a PC-based image analyser. The effect of image analyser settings, magnification, image orientation and threshold levels was determined. Also, the range of scale over which trabecular bone is effectively fractal was determined and a method formulated to calculate objectively more than one fractal dimension from the modified Richardson plot.
The results show that magnification, image orientation and threshold settings have little effect on the estimate of fractal dimension. Trabecular bone has a lower limit below which it is not fractal (λ < 25 μm) and the upper limit is 4250 μm. There are three distinct fractal dimensions for trabecular bone (sectional fractals), with magnitudes greater than 1.0 and less than 2.0.
It has been shown that trabecular bone is effectively fractal over a defined range of scale. Also, within this range, there is more than one fractal dimension, describing spatial structural entities. Fractal analysis is a model-independent method for describing a complex multifaceted structure, which can be adapted for the study of other biological systems. This may be at the cell, tissue or organ level and complements conventional histomorphometric and stereological techniques. 相似文献
A modified box counting method has been developed for use on a PC-based image analyser. The effect of image analyser settings, magnification, image orientation and threshold levels was determined. Also, the range of scale over which trabecular bone is effectively fractal was determined and a method formulated to calculate objectively more than one fractal dimension from the modified Richardson plot.
The results show that magnification, image orientation and threshold settings have little effect on the estimate of fractal dimension. Trabecular bone has a lower limit below which it is not fractal (λ < 25 μm) and the upper limit is 4250 μm. There are three distinct fractal dimensions for trabecular bone (sectional fractals), with magnitudes greater than 1.0 and less than 2.0.
It has been shown that trabecular bone is effectively fractal over a defined range of scale. Also, within this range, there is more than one fractal dimension, describing spatial structural entities. Fractal analysis is a model-independent method for describing a complex multifaceted structure, which can be adapted for the study of other biological systems. This may be at the cell, tissue or organ level and complements conventional histomorphometric and stereological techniques. 相似文献
97.
98.
A modified rainflow counting method 总被引:1,自引:0,他引:1
Nie Hong 《International Journal of Fatigue》1991,13(6):465-469
The rainflow counting method is commonly recognized to be a good cyclic counting method in fatigue life prediction and for testing engineering components and structures. However, it has some shortcomings, which are pointed out in this paper in connection with the analysis of the stress-strain response. A modified rainflow counting method is presented. Case studies show that all the cycles really existing in the stress-strain response that cannot be counted by the rainflow counting method can be counted by the modified rainflow counting method. So it can be said that the modified rainflow counting method is a more reasonable cycling counting method than the traditional rainflow counting method. 相似文献
99.
R. Sunder 《International Journal of Fatigue》1985,7(1):3-12
Procedures have been developed for computer-controlled crack propagation testing under random load sequences. They include certain features which are not available in conventional systems, but which appear essential for random load testing. These include the capability to simulate any desired K-function on standard laboratory specimens and continuous on-line rainflow analysis of the test load sequence to exclude cycles falling below given values of threshold stress intensity, stress level or range. The system also includes a procedure for automated crack-opening displacement based crack opening/closing load level measurement. Experimental studies on AlCu alloy sheet material point to a requirement for development of standards for spectrum loading crack growth testing. 相似文献
100.