Spatial variation law of vertical derivative zero points for potential field data

In this paper we deduce the analytic solutions of the first- and second-order vertical derivative zero points for gravity anomalies in simple regular models with single, double, and multiple edges and analyze their spatial variation. For another simple regular models where it is difficult to obtain the analytic expression of the zero point, we try to use the profile zero points to analyze the spatial variation. The test results show that the spatial variation laws of both first- and second-order vertical derivative zero points are almost the same but the second-order derivative zero point position is closer to the top surface edge of the geological bodies than the first-order vertical derivative and has a relatively high resolution. Moreover, with an increase in buried depth, for a single boundary model, the vertical derivative zero point location tends to move from the top surface edge to the outside of the buried body but finally converges to a fixed value. For a double boundary model, the vertical derivative zero point location tends to migrate from the top surface edge to the outside of the buried body. For multiple boundary models, the vertical derivative zero point location converges from the top surface edge to the outside of the buried body where some zero points coincide and finally vanish. Finally, the effectiveness and reliability of the proposed method is verified using real field data.

Variation Law of Pericarp Tenderness of Super Sweet Corn Kernel

To investigate the variation law of pericarp tenderness in growth progress of super sweet corn kernel, the values of pericarp tenderness of 10 super sweet corn inbreeds were measured during kernel growth, and the variations under differ- ent conditions were analyzed. The results showed that there existed gradient differ- ences in pericarp tenderness among the 10 materials, of which PE10 had the best pericarp tenderness, T105 took medial place, and $33205 performed worst in peri- carp tenderness. Pericarp tenderness values of these 3 inbreeds increased curvedly from 12 to 24 days after pollination, in the spring （Wuhan, Hubei） and winter （Ling- shui, Hainan） of 2014. Moreover, the average pericarp tenderness at different time points presented the same decreasing order of $33205, T105, PE10, which was not altered by enviroment. With the growth of kernel, for one material, the difference of pericarp tenderness under different environments presented a law of increment, re- duction, uniformity. As for optimum-picking time, there was four days difference be- tween the spring in Wuhan and winter in Lingshui. However, there was no obvious difference in pericarp tenderness on the optimum picking time, which indicated that growing environment could affect the variation ratio of pericarp tenderness, but it still depended on the nature of materials.

Variation law of microscopic pore of loess-like soil after several freeze-thaw cycles in seasonal frozen soil region

In seasonal frozen soil region,the engineering geological properties of loess-like soil will be deteriorated after freeze-thaw cycles.Through the freeze-thaw cycle experiment of remolded loess-like soil,under different freezing temperatures,the authors carried out freeze-thaw cycle tests for 3 times and 20 times,respectively.With mercury intrusion porosimetry and granulometric analysis,from the micro-structure,the authors studied the law that freeze-thaw cycle times and frozen temperature effect on the variation of microscopic pore of loesslike soil.This result can provide theoretical basis for comprehensive treatment of problems in the construction of the project in seasonal frozen loess-like soil region.

Study on Changes of Microclimate in Greenhouse of Pleurotus nebrodensis in Jizhou, Tianjin

Based on the air temperature (1.0 m and 1.5 m) every 10 minutes, ground temperature (0 cm, 10 cm and 20 cm) and air relative humidity (1.5 m) from the stations in the greenhouse, and the air temperature (1.5 m) every 10 minutes and air relative humidity (1.5 m) from the regional stations in Chutouling Town, Jizhou district of Tianjin from April 2019 to November 2020, the changes of the microclimate in the greenhouse of Pleurotus nebrodensis were studied. The results explained that 1) the heat preservation effect of the greenhouse was the best in spring, the effective accumulative temperature and active accumulated temperature in the greenhouse had increased by 203.7°C and 233.7°C, respectively, compared with that outside the greenhouse. In the sunny or cloudy days of summer, the range of temperature difference (TD) between inside and outside the greenhouse was wider, more than 90% of the TD ranged from -6.0°C to 2.9°C;2) the minimum temperature occurred later because of heat preservation effect of the greenhouse, the delay time can reach about 30 minutes in spring, it was about 20 minutes in summer and autumn, and 10 minutes in winter, however, the maximum temperature appeared earlier, it occurred 50 minutes ahead of time in spring, and it has been advanced by 20 minutes in summer and 10 minutes in autumn and winter;3) the greenhouse mainly played a role of increasing humidity, the humidity in the greenhouse basically was larger than that outside the greenhouse, except the periods of 03:10-07:20 in spring, 0:00-08:50 and 23:10-23:50 in winter;4) the temperature in the greenhouse significantly positively correlated with the temperature outside the greenhouse, the stronger correlation also appeared between the ground temperature (at the depth of 0 cm and 10 cm) in the greenhouse and the temperature inside and outside the greenhouse, however, there was a weak correlation between the ground temperature (20 cm) and the temperature inside and outside the greenhouse, this implies that the change of temperature had less impact on the ground temperature at deeper soil layers. This paper is of significance in identifying the microclimate in the Pleurotus nebrodensis greenhouse.

The Variable-Step L1 Scheme Preserving a Compatible Energy Law for Time-Fractional Allen-Cahn Equation

In this work,we revisit the adaptive L1 time-stepping scheme for solving the time-fractional Allen-Cahn equation in the Caputo’s form.The L1 implicit scheme is shown to preserve a variational energy dissipation law on arbitrary nonuniform time meshes by using the recent discrete analysis tools,i.e.,the discrete orthogonal convolution kernels and discrete complementary convolution kernels.Then the discrete embedding techniques and the fractional Gronwall inequality are applied to establish an L^(2)norm error estimate on nonuniform time meshes.An adaptive time-stepping strategy according to the dynamical feature of the system is presented to capture the multi-scale behaviors and to improve the computational performance.