LTD多间隙气体开关电场优化及自放率实验研究

气体开关自放电是制约直线变压器驱动源(linear transformer driver,LTD)应用的主要原因,降低气体开关自放率,对LTD技术发展和工程应用具有重要意义。本文开展了气体开关间隙电场仿真研究,确定了优化的环形电极结构参数,设计了4间隙串联气体开关;实验研究了单只气体开关击穿特性,通过万发次触发考核获得自放率;批量试制了23只气体开关,测试了自击穿特性,将开关应用于单级LTD模块,测试了模块连续运行百发次的自放率。结果表明,工作电压为±80 kV、工作系数为0.70时,单只开关自放率小于0.03%;自击穿电压为±80 kV时,23只气体开关分散性均小于3%;工作电压为±80 kV,工作系数为0.65时,LTD模块开关连续运行303发,模块自放率为1.32%。

Effects of pyrite on the spontaneous combustion of coal

Abstract Pyrite has a significant effect on the spontaneous combustion of coal. The presence of pyrite can change the propensity of coal towards spontaneous combustion. The influences of various pyrite contents on the parameters of spontaneous combustion, such as index gases, temperature and released heat etc., were investigated in this study, Coal samples with different pyrite contents （0 %, 3 %, 5 %, 7 % and 9 %） were made by mixing coal and pyrite. The oxidation experiments under temperature-programmed condition were carried out to test the release rate of gaseous oxidation products at different temperatures. Differential scanning calorimeter （DSC） was employed to measure the intensity of heat release during coal oxidation for various pyrite contents. The results indicate that pyrite can nonlinearly accelerate the process of spontaneous combustion. The coal sample with a pyrite content of 5 % has the largest CO release rate and oxygen adsorption as well. However, the coal sample with a pyrite content of ？ % has the largest rate of heat flow according to the results from the DSC tests. Pyrite contents of 5 %-7 % in coal has the most significant effects on spontaneous combustion within the range of this study. The conclusions are conducive to the evaluation and control for the spontaneous combustion of coal.

Corrosion and discharge performance of Mg-9%Al-2.5%Pb alloy as anode for seawater activated battery

To obtain a new kind of Mg?Al?Pb alloy anode material with low content of Pb, the corrosion and discharge behavior of Mg?9%Al?2.5%Pb (hereafter in mass fraction) alloy were investigated by immersion tests and electrochemical techniques, and compared with those of Mg?6%Al?5%Pb alloy. The results indicate that Mg?9%Al?2.5%Pb alloy exhibits a lower self-corrosion rate and higher utilization efficiency in contrast with Mg?6%Al?5%Pb alloy because of the higher content of Al. As the result of the decrease of Pb content, the discharge activity of Mg?9%Al?2.5%Pb alloy is relatively weaker but still meets the requirement of anode. These results reveal that Mg?9%Al?2.5%Pb alloy with a low content of Pb can serve as a good candidate for the anode material used in seawater activated battery.

Research on Novel Natural Image Reconstruction and Representation Algorithm based on Clustering and Modified Neural Network

In this paper, we conduct research on the novel natural image reconstruction and representation algorithm based on clustenng and modified neural network. Image resolution enhancement is one of the earliest researches of single image interpolation. Although the traditional interpolation and method for single image amplification is effect, but did not provide more useful information. Our method combines the neural network and the clustering approach. The experiment shows that our method performs well and satisfactory.

Sexual dimorphism of the electrophysiological properties of the projection neurons in the robust nucleus of the arcopallium in adult zebra finches

Objective To observe the sexual differences in electrophysiological properties of neurons in the robust nucleus of the arcopallium （RA） in adult zebra finches, and to provide the direct electrophysiological evidence for the sexual dimorphism of birdsong. Methods Whole-cell recording was used to record the spontaneous action potential firing rates from RA projection neurons in acute brain slices. Results The projection neurons of RA in male birds fired spontaneously at 10 Hz or above, while in female birds, the frequency was significantly lower, and even no firings could be detected. Conclusion There is a sexual difference in electrophysiological properties of projection neurons in RA, which may result from the difference in the levels of steroid hormones in birds.

Maximizing the ion accessibility and high mechanical strength in nanoscale ion channel MXene electrodes for high-capacity zinc-ion energy storage

Two-dimensional transition-metal carbides(MXenes)have superhydrophilic surfaces and superior metal conductivity,making them competitive in the field of electrochemical energy storage.However,MXenes with layered structures are easily stackable,which reduces the ion accessibility and transport paths,thus limiting their electrochemical performance.To fully exploit the advantages of MXenes in electrochemical energy storage,this study reports the etching of large-sized MXene into nanosheets with nanoscale ion channels via a chemical oxidation method.While the resulting ion-channel MXene electrodes retain the excellent mechanical strength and electrical conductivity of large-sized MXene nanosheets,they can effectively shorten the ion transport distance and improve the overall electrochemical activity.The fabricated self-healing MXene-based zinc-ion microcapacitor exhibits a high areal specific capacitance(532.8 mF cm^(-2))at the current density of 2mA cm^(-2),a low self-discharge rate(4.4 mV h^(-1)),and high energy density of 145.1μWh cm^(-2)at the power density of 2800μW cm^(-2).The proposed nanoscale ion channel structure provides an alternative strategy for constructing high-performance electrochemical energy storage electrodes,and has great application prospects in the fields of electrochemical energy storage and flexible electronics.