Density field measurement deflectometry for supersonic wind tunnels.

A method for the quantitative measurement of two-dimensional density field distributions based on deflectometry is proposed. With this method, from the point of view of the inverse Hartmann test, the light rays emitted from the camera reach the screen after being disturbed by the shock-wave flow field. After the coordinates of the point source are obtained by using the phase information, the deflection angle of the light ray can be calculated, and then the distribution of the density field can be determined. The principle of density field measurement deflectometry (DFMD) is described in detail. In the experiment, the density fields in wedge-shaped models with three different wedge angles are measured in supersonic wind tunnels, the experimental results from the proposed method are compared with the theoretical results, and the measurement error is found to be around 2.76 × 10-3kg/m3. This method has the advantages of fast measurement, a simple device, and low cost. It provides a new approach, to the best of our knowledge, to measuring the density field of a shock-wave flow field.

[Dynamics of litterfall and its decomposition and nutrient return of shoot-used Dendrocalamus latiflorus in Mountainous areas of Fujian Province].

This paper studied the dynamics of nutrients in the litters of shoot-used Dendrocalamus latiflorus planted Nanjing State-owned Forest Farm of Fujian Province. The results showed that the litterfall as well as its nutrient concentration and return varied obviously with seasons, and had a double-peak curve change. The weight loss during litter decomposition was very fast at first, and then slowed down. There was a negative exponent correlation between remained weight and decomposition time. During decomposition, the concentrations of N and P in litter showed a trend of increase-decrease-increase, while the K loss was intensive at the early stage, gently at mid-stage, and slight at late stage.

[Transpiration water consumption of young Platycladus orientalis and Robinia pseudoacacia trees and their correction functions under different water supply].

Through artificial water control in the shed of rain-free, this paper studied the physiological water requirement patterns of 2-3 years old Platycladus orientalis and Robinia pseudoacacia trees during their growth period, and the relationships between their transpiration water consumption and soil water supply. The results showed that the transpiration water consumption of Robinia pseudoacacia was increased with increasing soil water supply within the range of 40%-100% of field water-holding capacity. Its maximum transpiration water consumption was at the early and accelerating growth stages, accounted for 80.5% of total annual water consumption. The transpiration water consumption of Robinia pseudoacacia was 5.13 times as much as that of Platycladus orientalis. Platycladus orientalis had a peak value of transpiration water consumption when the soil moisture content was 40%-100% of field water-holding capacity. Its transpiration water consumption was the maximum at accelerating growth stage, accounted for 46.27% of total annual water consumption, next at later growth stage, and relatively small at early growth stage. The correction functions of transpiration water consumption to soil water supply and the time-soil moisture functions of practical transpiration water consumption under insufficient water supply for two test species were put forward for the first time.