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Runoff and nutrient loss in drylands are closely related to vegetation cover. Simulated rainfall experiments with an intensity of 80 mm/h were conducted in sandy grassland and shrubland in the Tengger Desert, China, to investigate the responses of runoff and associated carbon (C) and nitrogen (N) losses to the replacement of grassland by shrubland. Times to ponding and to generate runoff, and the amount of rainfall for runoff commencement in bare, inter-shrub plots were significantly smaller than in shrub (ST) and grassland (GT) plots; no statistical differences were found for these parameters between ST and GT. Overall, this indicated a higher soil water infiltration rate in grassland than in shrubland. The volume-weighted concentrations of organic C (OC) and total N (TN) in runoff from shrubland (0.083 and 0.011 g/L, respectively) were lower than those from grassland (0.103 and 0.012 g/L, respectively). The cover-weighted runoff coefficients, and sediment, OC, and TN losses from shrubland (34.46%, and 44.95 1.72, and 0.23 g/[m.sup.2], respectively) were greater than from grassland (15.22%, and 15.91, 0.94, and 0.11 g/[m.sup.2]). Vegetation degradation was accompanied by reduced nutrient retention capacity; both soil OC and TN of grassland (8.97 and 0.62 g/kg, respectively) were greater than those weighted values for shrubland (4.18 and 0.26 g/kg). Understanding of these processes suggests that decline or loss of vegetation cover, with the appearance of biological soil crust patches, inevitably leads to increases in runoff and induced soil loss, further accelerating desertification. Additional keywords: biological soil crust, nutrient loss, runoff, Tengger Desert, vegetation degradation., Introduction Vegetation change is a crucial issue globally for desert grasslands in arid and semi-arid regions. One of the most serious challenges is the increase of shrub-dominated communities in regions [...]

Virtual space vector pulsewidth modulation (VSVPWM) provides a new approach to neutral point voltage (NPV) control and common mode voltage (CMV) suppression. Few values of coefficients configured in the virtual vectors cannot adjust the NPV continuously. An improved VSVPWM (IVSVPWM) with active neutral point voltage control (ANPVC) and CMV suppression is proposed in this article. Continuously variable coefficients configured in the virtual vectors adjust the NPV actively and continuously for any load power factor over the full modulation indexes. Failure of CMV suppression is analyzed, and the undesired vectors with high CMV are avoided by limiting the range of the variable coefficients. The limited variable coefficients and the selected basic vectors with low CMV suppress the CMV effectively. Simulation and experimental results are given to validate the proposed novel IVSVPWM, which can achieve quicker ANPVC and reduce CMV to half of the conventional VSVPWM simultaneously. [ABSTRACT FROM AUTHOR]

The article focuses on a study which examined the carbon isotope ratio values in Corbicular fluminea shells. Samples of Corbicula fluminea were collected from the Huaxi River in Guizhou Province, South China. Results of the study showed that the carbon isotope ratio values were more negative than expected. It also observed a decrease in these values through ontogeny. It points out that the increased use of metabolic carbon for calcification led to the decrease in carbon isotope ratio values.

In this paper, the key factors of heat island effect in Zhengzhou city were monitored by grid method to study the diurnal and seasonal changes and the spatial distribution of the effect, and to evaluate the comfortable degree of human bodies at different sites of the city. The results showed that on the whole, the heat island effect had a unimodal diurnal change, while its intensity was distinctly different among seasons, being decreased in order of winter > spring > autumn > summer. The spatial distribution of heat island center was significantly related to its nearby industrial heat resources. As for the comfortable degree of human bodies, the People's Park was the best site because of its arbor virescence, while in the Xiliu Lake Park with lawn as its main greening type, its capability of improving microclimate was weaker. The railway station square still had 16% frequency of most comfortable degree, because of its open space and better air fluidity.