Search

Ginseng and American ginseng need to be covered and protected against cold in winter to survive, and covering and uncovering date has great influences on safe overwintering and seedling emergence. To determine the optimal time, field experiments are conducted at Fusong of Jilin Province from November 2021 to June 2022. Effects of different covering dates on the soil temperature in the overwintering layer and seedling emergence rate of ginseng and American ginseng are studied through different experiment themes. For some cases they are covered in stages in early winter and simultaneously uncovered in spring, and there are also other cases when the ginseng and American ginseng are covered simultaneously in early winter and uncovered step by step in spring. Results show that the emergence rate of ginseng and American ginseng decreases with the delay of coverage date. When 5 cm soil temperature is 0℃, the coverage date for cold prevention is the best, with the highest emergence rate of ginseng and American ginseng. Below -12℃, most or all of American ginseng is frozen to death. When the instantaneous 5 cm soil temperature drops to -14℃, the emergence rate of ginseng still reaches 75%. The emergence rate of ginseng seedlings in other treatments above this temperature coverage is mostly over 86%. When the soil temperature is -7℃ or above, the emergence rate of ginseng seedlings is above 97%. The emergence rate of ginseng seedlings covered by snow is 91%. The soil temperature fluctuates between -14℃ and -8℃, and all uncovered ginseng with an extreme minimum of -16℃ is frozen to death. When ginseng seedlings emerge, the soil temperature of 5-20 cm is around 8-9℃, slightly higher than that of American ginseng. Covering with high insulation fibers to prevent cold, the later the cover is removed, the lower the soil temperature becomes, and the later the seedlings emerge. The date of uncovering affects the progress of seedling emergence, but has little correlation with the emergence rate. The optimal date of uncovering needs to be analyzed further. On frost prone areas in early spring, combined with climate prediction, the emergence progress can be adjusted by uncovering date to avoid spring freezing damage.

During probe‐to‐Earth superior conjunction, deep space communication channels will suffer from solar scintillation, leading to amplitude attenuation of received signals. This study aims to obtain the channel state information (CSI) on deep space channels affected by solar scintillation. Classical least squares (LS) and minimum mean squared error (MMSE) methods are adopted to perform channel estimation and compensate for the channel fading. Simulation results indicate that under the effect of solar scintillation, performing channel estimation technology can significantly improve bit error rate (BER) performance compared to systems without CSI, and the MMSE algorithm outperforms the LS for both BER and normalized mean squared error (NMSE). In addition, we also find that pilot density, geometric parameters, and the outer scale of solar wind turbulence has great influence on the estimation performance. Key Points: Performed channel estimation for deep space communications under solar scintillationLeast squares (LS) and minimum mean squared error (MMSE) methods were adopted for channel estimationSimulated the impact of pilot density, geometric parameters, and outer scale of solar wind turbulence on performance of channel estimation [ABSTRACT FROM AUTHOR]

The interturn short circuit fault is one of the common faults in power transformers. At present, research on interturn short circuit faults focuses on high, medium, and low voltage windings, while there is relatively little research on interturn short circuit in regulating windings. Specifically, there is a lack of reported studies on the transient electromagnetic processes, magnetic field distribution, and electromagnetic force characteristics of interturn short circuits in regulating windings unconnected to the circuit. This study presents an actual fault scenario involving interturn short circuits occurring in the untapped portion of the regulating windings of a specific power transformer. A field-circuit coupled model was established to analyze the transient electromagnetic processes during the fault, and the model's effectiveness was validated by comparing its results with actual fault recording data. Additionally, the magnetic field distribution and electromagnetic force characteristics during the fault were analyzed, and discussions were carried out regarding various ratios of short-circuit turns in the regulating windings. The results indicate that even when an interturn short circuit occurs in the portion of the regulating winding that is not connected to the circuit, the current in the short-circuited turns can reach several tens of times the rated value. Additionally, the leakage magnetic field and the electromagnetic force experienced by the short-circuited ring also increase significantly. The short-circuit ratio has a significant impact on the current of the short-circuited ring, leakage magnetic field intensity, and electromagnetic force. This study contributes to a better understanding of the impact of interturn shortcircuit faults in the untapped portion of the regulating windings, offering crucial technical support for fault diagnosis and prevention of power transformers. [ABSTRACT FROM AUTHOR]

Being a vital component of electrical power systems, transformers significantly influence the system stability and reliability of power supplies. Damage to transformers may lead to significant economic losses. The efficient identification of transformer faults holds paramount importance for the stability and security of power grids. The existing methods for identifying transformer faults include oil chromatography analysis, temperature assessment, frequency response analysis, vibration characteristic examination, and leakage magnetic field analysis. These methods suffer from limitations such as limited sensitivity, complexity in operation, and a high demand for specialized skills. In this paper, we propose a method to identify external short-circuit faults of power transformers based on fault recording data on short-circuit currents. It involves analyzing the current signals of various windings during faults, extracting appropriate features, and utilizing a classification algorithm based on a support vector machine (SVM) to determine fault types and locations. The influence of different kernel functions on the classification accuracy of SVM is discussed. The results indicate that this method can proficiently identify the type and location of external short-circuit faults in transformers, achieving an accuracy rate of 98.3%. [ABSTRACT FROM AUTHOR]

We have developed a screening technology for the identification of short-lived proteins. A green fluorescent protein (GFP)-fusion cDNA library was generated for monitoring degradation kinetics. Cells expressing a subset of the GFP-cDNA expression library were screened to recover those in which the fluorescence signal diminished rapidly when protein synthesis was inhibited. Thirty clones that met the screening criteria were characterized individually. Twenty-three (73%) proved to have a half-life of 4 hours or less.

As the global climate crisis escalates, reductions in CO2 emissions and the efficient utilization of carbon waste resources have become a crucial consensus. Among the various carbon mitigation technologies, the concept of power-to-liquid (PTL) has gained significant attention in recent years. Considering the lack of a timely review of the state-of-the-art progress of this PTL process, this work aims to provide a systematic summary of the advanced PTL progress. In a CO2 capture unit, we compared the process performances of chemical absorption, physical absorption, pressure swing adsorption, and membrane separation technologies. In a water electrolysis unit, the research progress of alkaline water electrolysis, proton exchange membrane water electrolysis, and solid oxide water electrolysis technologies was summarized, and the strategies for improving the electrolysis efficiency were proposed. In a CO2 hydrogenation unit, we compared the differences of high-temperature and low-temperature Fischer–Tropsch synthesis processes, and summarized the advanced technologies for promoting the conversion of CO2 into high value-added hydrocarbons and achieving the efficient utilization of C1–C4 hydrocarbons. In addition, we critically reviewed the technical and economic performances of the PTL process. By shedding light on the current state of research and identifying its crucial factors, this work is conducive to enhancing the understanding of the PTL process and providing reliable suggestions for its future industrial application. By offering valuable insights into the PTL process, this work also contributes to paving the way for the development of more efficient and sustainable solutions to address the pressing challenges of CO2 emissions and climate change. [ABSTRACT FROM AUTHOR]