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Introduction: The continuous application of cow manure in soil for many years leads to the accumulation of heavy metals, pathogenic microorganisms, and antibiotic resistance genes. Therefore, in recent years, cow manure has often been mixed with botanical oil meal as organic fertilizer applied to farmland to improve soil and crop quality. However, the effects of various botanical oil meal and cow manure mixed organic fertilizers on soil microbial composition, community structure, and function, tobacco yield, and quality remain unclear. Methods: Therefore, we prepared organic manure via solid fermentation by mixing cow manure with different oil meals (soybean meal, rape meal, peanut bran, sesame meal). Then, we studied its effects on soil microbial community structure and function, physicochemical properties, enzyme activities, tobacco yield and quality; then we analyzed the correlations between these factors. Results and discussion: Compared with cow manure alone, the four kinds of mixed botanical oil meal and cow manure improved the yield and quality of flue-cured tobacco to different degrees. Peanut bran, which significantly improved the soil available phosphorus, available potassium, and NO3--N, was the best addition. Compared with cow manure alone, soil fungal diversity was significantly decreased when rape meal or peanut bran was combined with cow manure, while soil bacterial and fungal abundance was significantly increased when rape meal was added compared with soybean meal or peanut bran. The addition of different botanical oil meals significantly enriched the subgroup_7 and Spingomonas bacteria and Chaetomium and Penicillium fungi in the soil. The relative abundances of functional genes of xenobiotics biodegradation and metabolism, soil endophytic fungi, and wood saprotroph functional groups increased. In addition, alkaline phosphatase had the greatest effect on soil microorganisms, while NO3--N had the least effect on soil microorganisms. In conclusion, the mixed application of cow manure and botanical oil meal increased the available phosphorus and potassium contents in soil; enriched beneficial microorganisms; promoted the metabolic function of soil microorganisms; increased the yield and quality of tobacco; and improved the soil microecology. [ABSTRACT FROM AUTHOR] more...

The effects of initial pressure, equivalence ratio, hydrogen fraction, and CO2 dilution ratio on the characteristics of ion currents and heat release rate (HRR) were comparatively investigated with natural gas as a fuel. Ion currents were measured with a central electrode; chamber pressure was measured with a pressure sensor, and HRR was calculated based on the measured pressure data. The feature parameters of the ion current and HRR correspond with each other; the start time, peak time, duration time, and peak values of the ion current and HRR have the same variation under the initial conditions. The interdependency between these parameters was discussed in detail. This study indicates that a good correlation exists between the characteristic parameters of the ion current and HRR under different initial conditions. The characteristic parameters of ion currents can be directly used to predict and analyze the HRR and the response dynamics of a flame in the combustion process. [ABSTRACT FROM AUTHOR] more...

The optimal configuration of a resection network plays an important role in the precision analysis of free stations. The two conditions of the optimal configuration for distance-only resection networks were derived. Based on the two conditions, the regular sector configuration was proposed, and the character of the optimal configuration was determined. Furthermore, the geometric dilution of precision (GDOP) for a generic direction resection network with n known points was deduced. The conclusion was reached that A-D-E-optimality cannot be simultaneously achieved in the direction resection network. The pursuit of only the lowest GDOP is impractical in engineering, whereas the E-optimality criterion is suitable in such a situation, as shown by cases with three known points. There are typically two E-optimal configurations for a three-known-point direction resection network, and the regular pattern was explored. Finally, the configuration of a heterogeneous resection network was analyzed. An in-depth understanding of the resection network configuration is provided, which is beneficial for developing an initial guess for the optimal resection network configuration in practice. [ABSTRACT FROM AUTHOR] more...

A predictive current control strategy can realize flexible regulation of three-phase grid-tied converters based on system behaviour prediction and cost function minimization. However, when the predictive current control strategy with conventional switching patterns is adopted, the predicted duration time for voltage vectors turns out to be negative in some cases, especially under the conditions of bidirectional power flows and transient situations, leading to system performance deteriorations. This paper aims to clarify the real reason for this phenomenon under bidirectional power flows, i.e., rectifier mode and inverter mode, and, furthermore, seeks to propose effective solutions. A detailed analysis of instantaneous current variations under different conditions was conducted. An enhanced predictive current control strategy with improved switching patterns was then proposed. An experimental platform was built based on a commercial converter produced by Danfoss, and moreover, relative experiments were carried out, confirming the superiority of the proposed scheme. [ABSTRACT FROM AUTHOR] more...

In this paper, a predictive direct power control (DPC) method without sector information and voltage vector selection is proposed for three-phase grid-connected converters. Different from conventional predictive direct power controllers, the proposed strategy always adopts fixed voltage vectors, instead of selecting voltage vectors according to the angular information of the grid-voltage vector or the virtual-flux vector. The converter switching time is obtained by minimizing the squared errors of the instantaneous active and reactive power. Switch duty cycles are then calculated and equivalently reconstructed. The proposed strategy not only presents rapid dynamic response due to the use of the predictive controller, but also possesses excellent steady-state performance as a result of duty cycle reconstruction. The main advantage of the proposed control scheme, compared with the classical DPC strategies, is that it is unnecessary to use sector information of the grid-voltage vector, and selection of active voltage vectors is also not required here. Therefore, incorrect selection of voltage vectors and the resulting performance deterioration are surely avoided, without the need of any additional compensation measures. An in-depth comparison and experimental assessment are given to validate the effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR] more...