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Control of evaporation from seasonally frozen soil is an important method for alleviating water shortages in arid and semi‐arid areas. To investigate the inhibition of soil evaporation by sand and the major factors that influence soil evaporation, a series of field experiments with five sand‐mulch thicknesses (0 cm, bare soil [BS], 1 cm [T1], 2 cm [T2], 3 cm [T3] and 4 cm [T4], with an average diameter of 1 mm) were conducted during the freeze–thaw period in Northern China. Soil evaporation characteristics in the three freeze–thaw stages were revealed and the major factors influencing soil evaporation were analysed using grey correlation analysis. The results showed that the cumulative soil evaporation decreased with increasing sand‐mulch thickness during the freeze–thaw period, and only small differences in soil evaporation were observed between the T3 and T4 treatments. The reduction in soil evaporation under different sand‐mulch thicknesses was 19.2–62.6% in the unstable freezing stage (P1), 2.0–28.3% in the stable freezing stage (P2) and 4.8–20.4% in the thawing stage (P3). In P1, solar radiation was a major factor influencing soil evaporation in all treatments and vapour pressure was a major factor in the sand‐mulch treatments, and the influence of relative humidity on soil evaporation decreased in the T4 treatment. During the coldest P2, solar radiation was lowest so that relative humidity and wind speed became the more dominant influence factors on soil evaporation in all treatments, and surface soil water content was a major factor in the sand‐mulch treatments. In P3, average air temperature and solar radiation were major factor influencing soil evaporation in all treatments and vapour pressure was a major factor in the BS and T1 treatments, whereas water surface evaporation was the major factor in the T2, T3 and T4 treatments. The results suggest that the addition of sand mulch in agricultural fields may be a beneficial practice to reduce water stress in arid and semi‐arid areas.

As an imperative method of investigating the internal mechanism of femtosecond lasers, traditional femtosecond laser modeling relies on the split-step Fourier method (SSFM) to iteratively resolve the nonlinear Schrodinger equation suffering from the large computation complexity. To realize inverse design and optimization of femtosecond lasers, numerous simulations of mode-locked fiber lasers with different cavity settings are required further highlighting the time-consuming problem induced by the large computation complexity. Here, a recurrent neural network is proposed to realize fast and accurate femtosecond mode-locked fiber laser modeling for the first time. The generalization over different cavity settings is achieved via our proposed prior information feeding method. With the acceleration of GPU, the mean time of the artificial intelligence (AI) model inferring 500 roundtrips is less than 0.1 s. Even on an identical CPU-based hardware platform, the AI model is still 6 times faster than the SSFM method. The proposed AI-enabled method is promising to become a standard approach to femtosecond laser modeling.

Transient confined-unconfined flow conversion caused by pumping in a confined aquifer (i.e., piezometric head drops below the top confined layer) is complicated, partly due to different hydraulic properties between confined and unconfined regions. For understanding mechanism of the transient confined-unconfined conversion, this paper develops a new analytical solution for the transient confined-unconfined flow toward a fully penetrating well in a confined aquifer. The analytical solution is used to investigate the impacts on drawdown simulation by differences of hydraulic properties, including transmissivity, storativity, and diffusivity defined as a ratio of transmissivity and storativity, between the confined and unconfined regions. It is found that neglecting the transmissivity difference may give an overestimation of drawdown. Instead, neglecting the diffusivity difference may lead to an underestimation of drawdown. The shape of drawdown-time curve is sensitive to the change of storativity ratio, S/Sy , between the confined and unconfined regions. With a series of drawdown data from pumping tests, the analytical solution can also be used to inversely estimate following parameters related to the transient confined-unconfined conversion: radial distance of conversion interface, diffusivity, and specific yield of the unconfined region. It is concluded that using constant transmissivity and diffusivity in theory can result in biased estimates of radial distance of the conversion interface and specific yield of the unconfined region in practice. The analytical solution is useful to gain insight about various factors related to the transient confined-unconfined conversion and can be used for the design of mine drainage and groundwater management in the mining area.

During freeze–thaw periods, the transformation between phreatic water and soil water will change the soil hydrothermal properties and affect the soil freezing and thawing in shallow groundwater areas. The purpose of this study was to determine the effect of four different groundwater table depths (GTDs) and two soil textures on the process of soil freezing and thawing during two successive freeze–thaw periods using the Simultaneous Heat and Water (SHAW) model. The results show that the frost depth was the maximum when the GTD was 1.0 m, and the maximum frost depths of sandy loam and fine sand were 97.6 and 98.9 cm, respectively. When the GTD was larger than 1.5 m, the maximum frost depth decreased with an increase in GTD, and the maximum frost depth of the soil profile was more sensitive to changes in the air temperature. The frost depth of the soil profile was linear with the square root of the accumulated negative soil surface temperature (ANST) under different GTDs. The ANST was influenced by the phreatic evaporation, and the soil freezing rate increased with an increase in GTD under the same ANST. This research is significant for the rational development of soil water and heat resources and the study of soil water–heat transfer in shallow groundwater areas.

This paper deals with alternative hosts of an egg parasitoid. Trichogramma dendrolimi Matsumura in three habitats: mixed forest, pure stand and sparse wood. The experiment was conducted in Liuyan County which is located in the eastern part of Hunan Province. The results suggested that there are 103 species of alternative Lepidopteran hosts for T. dendrolimi. There were two critical periods throughout the year when there were no eggs of Dendrolimus punctatus Walker and few eggs of alternative hosts available for ovipsition by the parasitoids.