Crop Production Simulation and Analysis of Climate Scenarios Based on the APSIM Model for the Long Term Run of the Western Loess Plateau

The APSIM model is an effective tool for making decisions on agricultural management. The model can simulate the biophysical process in farming systems, particularly economic and ecological features of the systems under climatic risk (Keating et al. 1998). The APSIM model has previously been used in the Loess Plateau (Tan, 2007; Chen et al. 2008). Based on climate data from the Loess Plateau from 1961-2010, we simulated three commonly grown crops, wheat, maize and lucerne. Additionally, by applying three climate change scenarios, we attempted to determine the production risk in the future, and gain an understanding of the impact of climate change on crop yield in the western Loess Plateau

Concurrent coupling of atomistic simulation and mesoscopic hydrodynamics for flows over soft multi-functional surfaces

We develop an efficient parallel multiscale method that bridges the atomistic and mesoscale regimes, from nanometer to micron and beyond, via concurrent coupling of atomistic simulation and mesoscopic dynamics. In particular, we combine an all-atom molecular dynamics (MD) description for specific atomistic details in the vicinity of the functional surface, with a dissipative particle dynamics (DPD) approach that captures mesoscopic hydrodynamics in the domain away from the functional surface. In order to achieve a seamless transition in dynamic properties we endow the MD simulation with a DPD thermostat, which is validated against experimental results by modeling water at different temperatures. We then validate the MD-DPD coupling method for transient Couette and Poiseuille flows, demonstrating that the concurrent MD-DPD coupling can resolve accurately the continuum-based analytical solutions. Subsequently, we simulate shear flows over polydimethylsiloxane (PDMS)-grafted surfaces (polymer brushes) for various grafting densities, and investigate the slip flow as a function of the shear stress. We verify that a "universal" power law exists for the sliplength, in agreement with published results. Having validated the MD-DPD coupling method, we simulate time-dependent flows past an endothelial glycocalyx layer (EGL) in a microchannel. Coupled simulation results elucidate the dynamics of EGL changing from an equilibrium state to a compressed state under shear by aligning the molecular structures along the shear direction. MD-DPD simulation results agree well with results of a single MD simulation, but with the former more than two orders of magnitude faster than the latter for system sizes above one micron.Comment: 11 pages, 12 figure

A Study of (

We deal with topics regarding (λ,μ)-fuzzy subgroups, mainly (λ,μ)-fuzzy cosets and (λ,μ)-fuzzy normal subgroups. We give basic properties of (λ,μ)-fuzzy subgroups and present some results related to (λ,μ)-fuzzy cosets and (λ,μ)-fuzzy normal subgroups

Long-Term Effects of Tillage and Residue Management on the Soil Microbial Community Structure in the Loess Plateau

The severe soil erosion present in the Loess Plateau of western China has resulted from a combination of highly erodible soil, variable rainfall and intensive cultivation (Shi and Shao 2000). Conservation agriculture practices, including no till, crop residue retention and crop rotation, have been found to increase crop yield, improve water use efficiency, reduce energy inputs and improve soil fertility (Bukert et al. 2000; Rahman et al. 2008). The soil microbial community function and structure play key roles in the decomposition of organic matter, nutrient cycling and altering the availability of nutrients to plants, which has been shown to change under conservation agriculture (González-Chávez et al. 2010). The aims of our research are to quantify impacts of tillage and crop residue management on soil microbial community structural diversity on the Loess Plateau by PLFA techniques

Temporal Variations in the Carbon and Nitrogen Ecological Stoichiometry of Lucerne

Ecological stoichiometry has been of great help in research investigating the coupling between plant and environment (Sterner and Elser 2002). It provides some synchronized evidence to explain the response and adaptability of plants to the environment. Carbon and nitrogen ecological stoichiometry (C/N) also embraces the use efficiency of nitrogen in plants. Previous research has focused on the spatial responses of plant C/N to different environmental factors (Yang and Wang 2011). However, there is still insufficient attention on the temporal variation in C/N, in the hope that such effort will help elucidate the mechanisms underlying plant growth/regrowth. Lucerne (Medicago sativa L) has long been globally utilised. It can be cut 3-4 times annually and lasts for many years. The regrowth process in lucerne is of fundamental importance for the continuous utilisation of the forage and the sustainability of lucerne production. In this study, temporal variations in carbon and nitrogen content and C/N were studied in lucerne leaf, stem and root, as part of an effort to clarify the lucerne growth/regrowth mechanisms from the viewpoint of ecological stoichiometry

Research on high-frequency quasi-periodic oscillations in generalized black-bounce spacetime

In order to solve problem of spacetime singularity in theoretical physics, researchers proposed the regular black holes (BH). The generalized black-bounce (GBB) spacetime, as a unified treatment of distinct kinds of geometries in the framework of general relativity (e.g. regular BH and wormholes), has been extensively studied. Firstly, we derive to give the explicit forms of Lagrangian for a nonlinear electromagnetic field and potential for a non-canonical phantom field in the action of gravitational system corresponding to GBB solution. Secondly, this paper computes the radius of the innermost stable circular orbit (ISCO) and the stable circular orbit region for different types of celestial bodies in GBB spacetime. The research suggests that traversable wormholes may have two ISCOs or one ISCO depending on the throat's scale, whereas regular BH and extremal BH possess only one ISCO. Thirdly, quasi-periodic oscillations (QPOs) have been found to be a reliable tool for testing gravitational theories. Therefore, we compute the radial and azimuthal epicyclic angular frequencies of particles oscillating on stable circular orbits around various celestial bodies and compare them with the oscillation frequency properties of schwarzschild BH. Moreover, due to the limited amount of research on the high-frequency quasi-periodic oscillations (HFQPOs) phenomenon and its generation mechanisms around particles near wormholes using observational data, this paper aims to study theoretical models that can simultaneously describe both BH and wormholes by fitting observational data. Using resonance models and associated frequency ratios, we are able to locate the resonances of different celestial bodies within the GBB spacetime.Comment: 20 pages, 8 figure

Features Extraction and Reconstruction of Country Risk based on Empirical EMD

AbstractIn the application of the Empirical Mode Decomposition (EMD), reconstruction to the intrinsic mode functions (IMFs) which are obtained by EMD is necessary in order to simplify analysis and make reconstruction results of more economic explanatory power. At present, there are two main reconstruction methods; one is based on the changing of data construction, represented by the fine- to-coarse method, the other one takes the correlation of the IMFs into consideration, for example, calculating the correlation between the marginal spectrums of different IMFs. In order to study the internal unity and differences between the two methods, country risk data of the BRICS countries are selected to make the empirical analysis. The results are as follows. Firstly, it is not reasonable that the residue obtained by the EMD is directly regarded as the trend of the original data. Secondly, by fine-to-coarse, all the IMFs can be reconstructed to three time scales, which are denoted as high-frequency mode, low-frequency mode and trend respectively, but explanation of these scales for the real situation is not satisfactory. At last, trend which is extracted based on the correlation of the IMF marginal spectrums can describe the basic behavior of the original data. Contrasted to fine-to-coarse, the results obtained by the second method are more reasonable