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The rapid and accurate estimation of soil loss by wind erosion still remains challenge. This study presents an improved scheme for estimating the soil loss by wind erosion of farmland. The method estimates the soil loss by wind erosion based on a comparison of the relative contents of erodible and non-erodible particles between the surface and sub-surface layers of the farmland ploughed layer after wind erosion. It is based on the features that the soil particle-size distribution of the sampling soil layer (approximately 2 cm) is relatively uniform, and that on the surface layer, wind erosion causes the relative numbers of erodible and non-erodible particles to decrease and increase, respectively. Estimations were performed using this method for the wind erosion periods (WEP) from Oct. of 2012 to May of 2013 and from Oct. of 2013 to April of 2014 and a large wind-erosion event (WEE) on May 3, 2014 in the Bashang area of Hebei Province. The results showed that the average soil loss of farmland by wind erosion from Oct. of 2012 to May of 2013 was 2852.14 g/m 2 with an average depth of 0.21 cm, while soil loss by wind from Oct. of 2013 to April of 2014 was 1199.17 g/m 2 with a mean depth of 0.08 cm. During the severe WEE on May 3, 2014, the average soil loss of farmland by wind erosion was 1299.19 g/m 2 with an average depth of 0.10 cm. The soil loss by wind erosion of ploughed and raked fields (PRF) was approximately twice as large as that of oat-stubble fields (OSF). The improved method of particle-size distribution comparison (IPSDC) has several advantages. It can not only calculate the wind erosion amount, but also the wind deposition amount. Slight changes in the sampling thickness and in the particle diameter range of the non-erodible particles will not obviously influence the results. Furthermore, the method is convenient, rapid, simple to implement. It is suitable for estimating the soil loss or deposition by wind erosion of farmland with flat surfaces and high contents of non-erodible materials.

STC-OFDM systems effectively overcome the disadvantage of inter symbol interference and frequency selective fading for Orthogonal Frequency Division Multiplexing communication systems, however, there are still some issues, such as how to suppressing mutual interference due to multi-antenna transmitting. In this paper, an improving algorithm combining with channel frequency response recovery is proposed, which recover the channel frequency response of the pilot before successive interference cancellation and reduce the effects of the channel frequency response estimation. Theoretical analysis and computer simulation shows that the proposal algorithm can improve performance of Bit Error Rate and suppress the interference in the STC-OFDM communication systems.

In this paper, effects of external electric fields on frictional behaviors of Al2O3/brass, Al2O3/stainless steel and Al2O3/carbon steel couples under boundary lubricating conditions were studied on a self-made plate/plate type tribotester. Emulsion of 1 wt% zinc stearate dispersed into deionized water was used as lubricant in the experiments. The experiment results have shown that external electric fields affect the friction coefficient and its fluctuation of each rubbing couple substantially. The three couples showed different rates of change in friction coefficient and different tendency of change as the field was turned on and off during the rubbing process. Results acquired from experiments carried out in a wide range of external voltage, from 0 to 110 V, indicating that friction coefficient of Al2O3/brass couple increases monotonously with the intensity of the external electric field, although no linear relationship was found between them.

Energy coupling is a key phenomenon in material processing techniques that use lasers. It is a complex physical process which involves numerous parameters, such as a material's refractive index, laser wavelength, angle of incidence, polarization, temperature, power, power intensity, surface roughness, and surface coating. Although there are some empirical and theoretical models of the dependence of the energy coupling efficiency (also known as absorptivity) on individual and/or groups of parameters, to date, there is no comprehensive model that addresses the wide array of parameters that affect energy coupling for laser material interactions. To address this need, several of the available models are examined, and a generic methodology is introduced and used to de-couple, classify and regroup the parameters.