No abstract

Nitrogen oxides (NO x ) are the main emissions of diesel engines. Selective catalytic reduction (SCR) is the main technology used to reduce NO x emissions from diesel engines. NO x conversion efficiency and ammonia (NH3) escape are the main indicators to evaluate SCR performance. In this work, the effects of diesel engine exhaust temperature and exhaust mass flow rate on the SCR performance under different atmospheric pressures were studied by the combination method of experiment and one-dimensional numerical simulation. At the same time, the response surface method (RSM) was used to analyze the interaction of atmospheric pressure, exhaust temperature, and exhaust mass flow rate on the SCR performance. The results show that the lower the atmospheric pressure, the lower the NO x conversion efficiency and ammonia escape. Under the same exhaust temperature, the lower the atmospheric pressure, the smaller the impact of exhaust mass flow rate on NO x conversion efficiency. According to the RSM results, the optimal NO x conversion efficiency is 78.6% under the combination working conditions of an atmospheric pressure of 100 kPa, exhaust temperature of 395 °C, and exhaust mass flow rate of 250 kg/h, and the NH3 escape is also at a low level of 1.7 g/cycle.

The Arboreal gas model on a finite graph G is the Bernoulli bond percolation on G conditioned on the event that the sampled subgraph is a forest. In this short note we study the arboreal gas on a regular tree wired at the leaves and obtain a comprehensive description of the weak limit of this model.

The Arboreal gas model on a finite graph G is the Bernoulli bond percolation on G conditioned on the event that the sampled subgraph is a forest. In this short note we study the arboreal gas on a regular tree wired at the leaves and obtain a comprehensive description of the weak limit of this model.

Discarded tires used as reinforced materials have distinctive merits, such as high tensile strength, good anti-friction, fine flexility and durability, which can be used in reinforced wall, embankment and slope etc. some successful applications of discarded tire in reinforced slope are introduced, which have not only obtained significant economic benefits, but also resulted in good social and ecological benefits. The environment stress resulted from the world black pollution of discarded tires may be relieved through these new geotechnical applications. Different reinforced pattern of discarded tires are compared. The result has shown that discarded tire used for reinforcement is a particularly useful method. The settlement need to be given attention during reinforced engineering. Clay soil is averted as reinforcement with discarded tires. The tire with inside wall removed and backfilled with sandy soil is a good reinforced pattern.