Search

In the field of agro-grassland, the synergism of phosphate (P) fertilization and Trichoderma inoculation in alfalfa production and the underlying mechanism of rare and abundant microbes that regulate rhizosphere soil processes in various environments are key but rarely studied topics. Here, we conducted field research through the inoculation/noninoculation of Trichoderma and five levels of phosphorus fertilizer to explore the biological relationships of rhizosphere soil properties, rare and abundant taxa, and alfalfa yields. Our results demonstrate that using Trichoderma inoculation and 15 g/m2 of phosphorus fertilizer exhibited optimal alfalfa yield compared with other treatments. alfalfa yields significantly (R2 = 0.33; p < 0.001) increased along with soil fertility. Both rare (RANOSIM = 0.900; p = 0.001) and abundant (RANOSIM = 0.769; p = 0.001) bacterial communities were significantly different under Trichoderma inoculation and P fertilization in a nonmetric multidimensional scaling (NMDS) analysis. Furthermore, different ecological processes dominated the rare and abundant bacterial community assembly. PLS-PM analysis showed that Trichoderma inoculation positively regulated the abundant bacteria community and P fertilization regimes manipulated the rare bacteria community, synergistically contributing to alfalfa yields. Overall, this article believes that inoculation with Trichoderma and appropriate application of phosphorus fertilizer can significantly increase alfalfa yield and affect soil enzyme activity, and the rhizosphere soil abundant and rare bacterial community characteristics have different responses to the synergistic effect of Trichoderma and phosphorus fertilizer. Our research emphasizes the fundamental role of abundant and rare microbes in maintaining crop production using Trichoderma inoculation and P fertilization. Therefore, distinguishing rare and abundant species is beneficial to comprehensively understanding microbial-driven processes and providing theoretical support for maintaining ecosystem productivity. [ABSTRACT FROM AUTHOR]

BACKGROUND: The stick tea thrips, Dendrothrips minowai Priesner, is one of the most important sucking pests that seriously infest tea plants (Camellia sinensis) in China. Given that D. minowai exhibit aggregation behaviors in tea plantations, this study evaluated the potential of aggregation pheromones for their control. RESULTS: H‐tube olfactometer assays showed that D. minowai larvae, adult females and adult males were significantly attracted to larvae rather than adult females and males under laboratory conditions. Subsequent gas chromatography–mass spectrometry analysis of volatiles from larvae, identified two larva‐specific components: dodecyl acetate and tetradecyl acetate. Electrophysiological and behavioral experiments confirmed the positive response of females and males to dodecyl acetate, tetradecyl acetate, and their blend (1:1.5). Deployment of these aggregation pheromones on sticky traps resulted in a 1.2‐ to 3.0‐fold increase in the capture of D. minowai adults compared with control traps. In addition, deployment of sticky traps baited with these aggregation pheromones within tea plantations resulted in a noteworthy reduction in the population of adult thrips per 100 leaves, 10 days following trap deployment. The reduction ranged from 29% to 59%, in comparison with the control. CONCLUSION: D. minowai larvae produce aggregation pheromones, dodecyl acetate and tetradecyl acetate, that can be useful for controlling tea thrips. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This article is a Commentary on Hu et al. (2023), 242: 333–343. [ABSTRACT FROM AUTHOR]

Deep Reinforcement Learning (DRL) is widely used in path planning with its powerful neural network fitting ability and learning ability. However, existing DRL-based methods use discrete action space and do not consider the impact of historical state information, resulting in the algorithm not being able to learn the optimal strategy to plan the path, and the planned path has arcs or too many corners, which does not meet the actual sailing requirements of the ship. In this paper, an optimized path planning method for coastal ships based on improved Deep Deterministic Policy Gradient (DDPG) and Douglas-Peucker (DP) algorithm is proposed. Firstly, Long Short-Term Memory (LSTM) is used to improve the network structure of DDPG, which uses the historical state information to approximate the current environmental state information, so that the predicted action is more accurate. On the other hand, the traditional reward function of DDPG may lead to low learning efficiency and convergence speed of the model. Hence, this paper improves the reward principle of traditional DDPG through the mainline reward function and auxiliary reward function, which not only helps to plan a better path for ship but also improves the convergence speed of the model. Secondly, aiming at the problem that too many turning points exist in the above-planned path which may increase the navigation risk, an improved DP algorithm is proposed to further optimize the planned path to make the final path more safe and economical. Finally, simulation experiments are carried out to verify the proposed method from the aspects of plan planning effect and convergence trend. Results show that the proposed method can plan safe and economic navigation paths and has good stability and convergence., Author(s): Yiquan Du [1]; Xiuguo Zhang (corresponding author) [1]; Zhiying Cao (corresponding author) [1]; Shaobo Wang [2]; Jiacheng Liang [1]; Fengge Zhang [1]; Jiawei Tang [1] 1. Introduction With the [...]

Large‐power high‐torque‐density direct‐drive permanent magnet synchronous motors (LHDPMSM) are more and more frequently used to drive ball mills, belt conveyors, scraper conveyors, etc. Aiming at the characteristics of large copper loss and high winding temperature rise of the LHDPMSM, an effective winding cooling enhancement technology based on winding overall potting (WOP) is presented. The manufacturing process and cooling principle of WOP is described in detail and compared with the traditional vacuum pressure impregnation (VPI). In order to solve the problem of complex modelling process and long calculation time of LHDPMSM thermal field caused by large volume and asymmetric fluid cooling structure, the lumped parameter thermal network (LPTN) considering both fluid cooling and winding potting is proposed. Then, the cooling capacity of WOP and VPI are compared by LPTN, and the influence of some major cooling system parameters on LHDPMSM temperature rise are also researched. Finally, in order to verify the correctness of the theoretical calculation results, two 450 kW LHDPMSM prototypes adopt WOP and VPI are manufactured, tested and compared. The theoretical and experimental results are highly consistent, which proves the effectiveness of WOP in winding cooling enhancement of LHDPMSM. [ABSTRACT FROM AUTHOR]

Simple Summary: We studied the activity patterns, population dynamics, and spatial distribution of Dendrothrips minowai Priesner, one of the most destructive pests of tea plants in tea plantations. A large proportion of D. minowai individuals were caught in traps placed at heights ranging from 5 cm below to 25 cm above the position of tender leaves at the top of the tea plant, with most captures at a height of 10 cm above this position. The flight activity of D. minowai was highest from 10:00 to 16:00 h on sunny days in the spring and from 06:00 to 10:00 h and from 16:00 to 20:00 h in the summer. The distributions of D. minowai females and nymphs on leaves were aggregated according to Taylor's power law and Lloyd's patchiness index. The D. minowai populations were dominated by females, and the density of males was high in June. The seasonal prevalence of tea thrips captured with sticky traps in the field was bimodal; adult thrips overwintered on the bottom leaves. The peak periods of activity were from April to June and from August to October. This work provides new insights that have implications for enhancing the efficacy of measures to control D. minowai. The stick tea thrips, D. minowai Priesner (Thysanoptera: Thripidae), is one of the most economically significant thrips pests of tea (Camellia sinensis (L.) O. Ktze.) in China. Here, we sampled D. minowai in tea plantations from 2019 to 2022 to characterize its activity patterns, population dynamics, and spatial distribution. A large proportion of D. minowai individuals were caught in traps placed at heights ranging from 5 cm below to 25 cm above the position of tender leaves at the top of the tea plant, and the greatest number of individuals were captured at a height of 10 cm from the position of tender leaves at the top of the tea plant. Thrips were most abundant from 10:00 to 16:00 h in the spring and from 06:00 to 10:00 h and from 16:00 to 20:00 h on sunny days in the summer. The spatial distribution of D. minowai females and nymphs was aggregated on leaves according to Taylor's power law (females: R2 = 0.92, b = 1.69 > 1; nymphs: R2 = 0.91, b = 2.29 > 1) and Lloyd's patchiness index (females and nymphs: C > 1, Ca > 0, I > 0, M*/m > 1). The D. minowai population was dominated by females, and male density increased in June. Adult thrips overwintered on the bottom leaves, and they were most abundant from April to June and from August to October. Our findings will aid efforts to control D. minowai populations. [ABSTRACT FROM AUTHOR]

The switched reluctance motor (SRM) benefits from its magnet-free nature, robust construction, low cost, flexible controls, and the ability to operate in harsh environments such as high temperatures and high pressure. It has received increasing attention for all-electric or multi-electric aircraft systems and electric vehicles (EVs) as compared with permanent magnet synchronous motors (PMSM) and other AC motors in some required high reliability and fault tolerance applications. However, the SRM is prone to considerable wind resistance due to the convex pole structure of the rotor during high-speed rotation, high torque ripple, and also vibration noise. Thus, it is currently a trending topic to develop special SRMs, tailored with high reliability and fault tolerance. Recent research demonstrates several promising feasible solutions to reduce torque ripples and enhance torque density and power factors, including changing topology of SRM, using advanced control methods, as well as different winding configurations. Among these options, the segmented switched reluctance motor (SSRM), as a deformation of the conventional topology, is shown to be capable of effectively optimizing the torque performance. Motivated by this advance, this paper aims to present a comprehensive literature review on the SSRM, first illustrating the development of the topology of the SRM, then providing a description as well as a classification according to the topology of the SSRM. In particular, we focus on the evolution of various kinds of segmental topology and improvement measures. Then, we discuss the performance, advantages, and disadvantages of various types of structures in terms of their electromagnetic aspects and their applications. Eventually, several promising future trends and application prospects of the SSRM are prospected, with the aim of shedding light on further research. In sum, the key contribution of this paper is to provide a valuable basis for detailed analyses of the structure and electromagnetic design of the SSRM that are expected to benefit future research. [ABSTRACT FROM AUTHOR]

With the rapid development of power electronic techniques and the increasing cost of permanent magnets (PMs) materials, switched reluctance motors (SRMs) have recently gained more attention. However, traditional SRMs have a relatively low torque density. For the sake of increasing the motor torque density, this paper proposes a novel segmental rotor type SRM. The proposed motor adopts hybrid stator poles and concentrated windings in the stator side and a segmental rotor structure in the rotor side, which is completely different from the structures of the traditional SRM. The special structure of the motor shortens the magnetic flux paths of the motor, separates the parts of the magnetic flux paths from one another, and eradicates the magnetic flux reversal in the motor stator in order to improve the electric utilization and output torque density of the motor. Meanwhile, the requirement of the magneto-motive force and the core loss of the motor is also decreased, thereby improving the efficiency of the motor. For the purpose of proving the proposed structure, the characteristics of the motor are analyzed using the finite element method and are compared to those of the traditional 12/8 SRM, which is designed for the same application. Moreover, the prototypes of the traditional 12/8 and proposed SRMs are manufactured, and experiments based on the prototypes are performed. Finally, the effectiveness of the structure of the proposed motor is further proven by the experimental results. [ABSTRACT FROM AUTHOR]

Unravelling the community assembly processes of arbuscular mycorrhizal fungi (AMF) and diazotrophs as well as their co‐existence under different soil fertility environments are vital to develop a better understanding of agroecosystem functions, which is a crucial yet poorly understood topic. We examined the soils from 99 typical alfalfa cultivation systems to formulate a comprehensive picture of AMF and diazotrophic community and presented the first simultaneous investigation of the assembly processes and their co‐existence. The distributions of both AMF and diazotrophic communities were significantly (p < 0.05) corresponded to soil integrated fertility index (IFI). We quantified the relative contributions of five ecological processes in AMF and diazotrophic community assembly under different soil fertility environments, with stochastic assembly primarily determined across all soil fertility groups. The coexistence networks of AMF and diazotrophs were also notably different among typical soil fertility systems, where the most complex interactions were observed in high fertility system while medium fertility system was found to be the simplest. The active hubs detected in different fertility system were sensitively responded to different soil variables. We offered new opportunities to improve agroecosystem functions, especially for legumes, by regulating the potential key species or indirectly manipulating their drivers. [ABSTRACT FROM AUTHOR]

Simple Summary: The stick tea thrip Dendrothrips minowai is a key pest in tea plantations in China. In recent years, plant-derived semiochemicals have attracted considerable attention as promising attractants for the management of thrips, due to their safety and low cost. In this study, compounds that have been reported to attract other thrips or emitted from tea plants were evaluated for their electroantennogram (EAG), behavioral tests and field trapping efficacy for D. minowai. The EAG relative response value of D. minowai evoked by p-anisaldehyde, 3-methyl butanal, (E)-β-ocimene, farnesene, nonanal, eugenol, (+)-α-pinene, limonene, (−)-α-pinene, and γ-terpinene was significantly higher than the other compounds. Meanwhile, p-anisaldehyde, eugenol, farnesene, methyl benzoate, 3-methyl butanal, (E)-β-ocimene, (−)-α-pinene, (+)-α-pinene, and γ-terpinene led to attraction or repellency responses of female D. minowai. In addition, trap capture numbers of female D. minowai on sticky traps baited with p-anisaldehyde, eugenol, farnesene, and 3-methyl butanal were significantly higher than the control in tea plantations. Overall, our results highlight the potential application of plant volatiles in the development of effective, eco-friendly lure formulations for use in the monitoring and management of thrips. The stick tea thrip (Dendrothrips minowai Priesner) is the main pest thrip in tea (Camellia sinensis) plantations in China, and seriously affects the quality and yield of tea. Plant-derived semiochemicals provide an alternative to pheromones as lures and these compounds possess powerful attractiveness. In this study, we selected 20 non-pheromone semiochemicals, including compounds that have been reported to attract other thrips and some volatiles emitted from tea plants as the potential attractant components for D. minowai. In electroantennogram (EAG) assays, 10 synthetic compounds (p-anisaldehyde, 3-methyl butanal, (E)-β-ocimene, farnesene, nonanal, eugenol, (+)-α-pinene, limonene, (−)-α-pinene, and γ-terpinene) elicited significant antennal responses in female D. minowai. In addition, a two-choice H-tube olfactometer bioassay showed that D. minowai displayed significant positive responses to eight compound dilutions (p-anisaldehyde, eugenol, farnesene, methyl benzoate, 3-methyl butanal, (E)-β-ocimene, (−)-α-pinene, and (+)-α-pinene) when compared with the solvent control at both 1 and 2 h. Moreover, γ-terpinene exhibited a significantly deterrent effect on D. minowai. Finally, trap catches of four compounds (p-anisaldehyde, eugenol, farnesene, and 3-methyl butanal, respectively) significantly increase in tea plantations. Among these, the maximum number of D. minowai collected by blue sticky traps baited with p-anisaldehyde was 7.7 times higher than the control. In conclusion, p-anisaldehyde, eugenol, farnesene, and 3-methyl butanal could significantly attract D. minowai in the laboratory and under field conditions, suggesting considerable potential as commercial attractants to control D. minowai populations. [ABSTRACT FROM AUTHOR]

The cage and reluctance rotors are two major types of rotor structures used in the doubly fed brushless machine (DFBM). In order to study comparatively the effects of different rotor structure on the DFBM, a prototype machine has been specially designed and built. The experimental parameter and performance comparisons between the axially laminated anisotropic (ALA) and cage-rotor machines are presented. It is found that the cage-rotor DFBM has better starting and asynchronous characteristics; however, the ALA reluctance-rotor DFBM exhibits better synchronous operation and doubly fed adjustable speed performance. Index Terms-Cage rotor, comparison, doubly fed brushless machine, performance, reluctance rotor.

Microbial generalists and specialists coexist in the soil environment while having distinctive impacts on microbial community dynamics. In microbial ecology, the underlying mechanisms as to why a species is a generalist or a specialist remain ambiguous. Herein, we collected soils across a national scale and identified bacterial generalists and specialists according to niche breadth at the species level (OTU level), and the single‐nucleotide differences in each species were measured to investigate intraspecific variation (at zero‐radius OTU level). Compared with that of the specialists, the intraspecific variation of the generalists was much higher, which ensured their wider niche breadth and lower variability. The higher asynchrony and different niche preferences of conspecific individuals and the higher dormancy potential within the generalists further contributed to their stability in varying environments. Besides, generalists were less controlled by environmental filtering, which was indicated by the stronger signature of stochastic processes in their assembly, and had higher diversification and transition rates that allowed them to adapt to environmental changes to a greater extent than specialists. Overall, this study provides a new comprehensive understanding of the rules of assembly and the evolutionary roles of bacterial generalists and specialists. It also highlights the importance of intraspecific variation and the dormancy potential in the stability of species. [ABSTRACT FROM AUTHOR]

The high‐temperature rise of rotor permanent magnet (PM) in high‐speed PM machine (HSPMM) is one of the main bottlenecks that limits the development of HSPMM. The main reason for the increase of the PM temperature is the eddy current loss caused by high‐frequency harmonics. In this study, a new type of composite magnetic material is studied, which greatly reduces the electrical conductivity of the PM and thus reduces the eddy current loss under the condition of ensuring the magnetic properties. The electrical conductivity of magnetic powder composites is calculated by introducing the improved effective medium model of the magnetic powder packing coefficient. Through the calculation of the porosity of the magnetic powder composite, the effects of the particle size, gradation and shape of the magnetic powder on the electrical conductivity of the composite were obtained. The model solves the problem of calculating the electrical conductivity of the powder structure composite rotor in eddy current loss calculation. The accuracy of the calculation is verified by the four‐probe method, which provides guidance for the design of a composite rotor HSPMM. [ABSTRACT FROM AUTHOR]