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The ionization chamber tritium monitor is the most important online monitoring equipment for monitoring the concentration of tritium in the air. In order to solve the problem of quantity value transmission, the calibration technology of ionization chamber tritium monitor was studied. The laboratory calibration device of tritium monitor is established according to the mass flow method. The reference tritium gas for calibration is diluted and prepared by controlling the volume of standard tritium gas filled into the calibration device. The prepared reference tritium gas is used to calibrate the ionization chamber tritium monitor. At the same time, the influence factors of the calibration process on the calibration results are studied on the developed laboratory calibration device; the expanded uncertainty of reference tritium gas concentration prepared by laboratory calibration device is 3.2%-3.6%(k=2); when tritium activity concentration is 3.10×103-1.98×105 Bq/L, the response linearity of SP1400 tritium monitor to tritium gas activity is good(r2=0.999 3), the calibration factor is 0.97, and the standard synthetic uncertainty is 4.3%-5.0%. The laboratory calibration device of tritium monitor can prepare tritium gas with different activity concentrations. The calibration method is simple to operate and easy to popularize, which can meet the needs of tritium monitor calibration.

The Hulunbuir Leymus chinensis Meadow Grassland is a grassland formation at the eastern end of the Central Asian Grassland Subregion in the Eurasian Grassland Region. It is one of the representative types of meadow grasslands, and its grassland ecosystem is undergoing dual pressures from human interference such as grazing and climate change, resulting in varying degrees of degradation. Based on the correlation between grazing disturbance intensity and grassland biomass, this paper selected the natural Leymus chinensis meadow inside and outside the fence in Hulunbeier area to carry out long-term observation on the composition of plant community in the field (enclosed in 2005), obtained the composition data of plant community in the meadow grassland (2009-2015), and studied the response of community coverage, community abundance, and community height to grazing intensity on this basis. Research has shown that enclosure significantly increases the aboveground biomass of grasslands, and the degree of improvement is positively correlated with the duration of enclosure; Meanwhile, moderate grazing interference will not cause a decrease in the abundance of grassland communities. Among them, the latter conclusion has enlightening significance for the grassland ecological compensation mechanism currently aimed at balancing grassland ecological protection and productivity improvement. Proper enclosure and grazing prohibition in severely degraded areas can help protect and build grasslands, partially reflecting the necessity of ecological compensation. At the same time, further analysis also indicates that there is still room for exploration in optimizing relevant policies. This study helps to deepen the understanding of grazing response and feedback mechanisms in grassland ecosystems, and can provide scientific basis for the protection and sustainable utilization of grassland ecosystems. [ABSTRACT FROM AUTHOR]

In order to improve security of technique process of automatic filling line of industrial detonator, a design scheme of control system of dosing machine based on PLC was put forward and composition and designs of software and hardware of the system were introduced in details. The system realizes automation of dosing process by controlling motor reversing and has manual and automatic operating ways with flexible switch. Besides, it can real-timely display running status of dosing system on monitoring interface of upper computer and has sound and light alarm function. The testing result showed that the system runs stably and has high reliability, which improves working efficiency of production line and reduces labor intensity.

A transmission-mode ultrasound computerized tomography system can obtain only incomplete tomographic projections of a bubbly gas/liquid two-phase flow. This is due to the high contrast in acoustic impedance distribution of the bubbles. The projections depend on the bubble distribution in liquid. A two-value logical back-projection filtering algorithm and a fan-shape beam geometry allow the system to perform better performance for an image reconstruction speed of 41.7 frames/s. The data acquisition speed is 667 frames/s for a Pentium/90 compatible computer.