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Generation and analysis of gear drive with tubular tooth surfaces having double contact points

Liang D., Chen B., Hua C., Liao R.

Archives of Civil and Mechanical Engineering

2017

Vol. 17, no. 2

318--325

The gear drive with tubular tooth surfaces having double contact points is proposed. The generation of gear pair is investigated based on two mismatched rack cutters. The basic tooth profiles of rack cutters for generating the pinion and the gear are designed, respectively. Mathematical models of tooth surfaces are derived according to the geometric relationships. Solid models of gear pair are also established. Stress analysis of tubular tooth surfaces having double contact points is carried out using the finite element method. The results show that the proposed gear drive has the better transmission characteristics. Gear prototype is finished with CNC machining technology. The further studies on the dynamic characteristics and experimental test of this gear drive will be carried out.

Responses of soil ß-glucosidase activities to simulated increased precipitation in a semi-arid temperate grasslands

Rui X., Liang D.

Polish Journal of Ecology

2013

Vol. 61, nr 2

401--404

In concurrent with global warming, precipitation regimes are predicted to change as well around the world. In this study, two experimental sites were selected with different nutrient availability along a slope to study the effects of simulated increased precipitation on soil β-glucosidase activities in an Inner Mongolian grassland. Soil samples were adjusted to 55% of water holding capacity and incubated at 22°C in the dark for 32 days. Soil β-glucosidase activities were measured prior to and after the incubation. Results showed that soil β-glucosidase activities had differential responses to increased precipitation with a significant increase in the downslope site, but not in the upslope site. Correlation analysis showed that the initial soil β-glucosidase activities exerted a significantly negative relationship with soluble organic nitrogen (N). Our results indicated that both water availability and soil soluble N availability played important roles in regulating β-glucosidase activities in this semiarid region.