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小电流直流电弧的动态模拟及其稳态特性研究 预览
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作者 朱冠南 杨晓艺 +3 位作者 高宇航 钟昱铭 熊兰 周林 《电测与仪表》 北大核心 2020年第1期42-48,共7页
直流电弧故障一旦发生,由于无过零点阶段,电弧不易熄灭,将严重危害直流供配电系统的安全运行,因此有必要研究小电流直流故障电弧的电气特性与温度场分布。电弧发展过程较为复杂,涉及电场、磁场、流体场与热力场等多个物理场的变化,建立... 直流电弧故障一旦发生,由于无过零点阶段,电弧不易熄灭,将严重危害直流供配电系统的安全运行,因此有必要研究小电流直流故障电弧的电气特性与温度场分布。电弧发展过程较为复杂,涉及电场、磁场、流体场与热力场等多个物理场的变化,建立了直流电弧的磁流体动力学模型,通过有限元分析方法模拟了电弧的发展过程,得到了直流电弧不同发展阶段的电弧电压、温度分布变化特点。同时,建立了电弧等效电阻的数值拟合模型,通过该模型获得的电弧电阻特性变化规律与实验数据基本吻合,电弧电阻与电弧电流呈反比例特性。分析了直流电弧稳态特性的影响因素,证明了电弧电流、电极间距是决定电弧特性的主要因素。以上研究结果为小电流直流电弧特性研究提供了新思路,为直流电弧的检测及保护装置的研究提供理论支持。 展开更多
关键词 直流 电弧 磁流体动力学 电弧电阻 温度场
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Design and characteristics of a new type laminar plasma torch for materials processing
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作者 曹修全 陈林 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2020年第1期24-32,共9页
Laminar plasma jet(LPJ)generated by laminar plasma torch(LPT)has a favorable temperature and velocity distribution.Thus,it is superior to the turbulent plasma jet in material processing.However,most of the reported LP... Laminar plasma jet(LPJ)generated by laminar plasma torch(LPT)has a favorable temperature and velocity distribution.Thus,it is superior to the turbulent plasma jet in material processing.However,most of the reported LPTs usually operate at a relatively low output power with a relatively low arc voltage and thermal efficiency,which limits its capabilities.In this context,this paper attempts to design a new type of high-power LPT with a relatively low arc current and a high thermal efficiency.In the first section,the design principle of the main components is studied and discussed in detail,and a new high-power LPT is proposed.Then,the experimental characteristics of the proposed high-power LPT are examined.Experimental results reveal the following characteristics of the proposed LPT.(1)The max jet length of the proposed LPT reaches at 540 mm.(2)Its mean arc voltage is higher than 290 V when the LPT works with arc currents lower than 200 A.leading to an output power greater than 50 kW.(3)The mean thermal efficiency is higher than 509f.Lastly,the proposed LPT has been applied to spheroidize the aluminum oxide powers.The experiment results for the production of spherical powders show that the proposed LPT hits a good characteristic for material processing. 展开更多
关键词 laminar plasma torch design principles high arc voltage with a low arc current spheroidisation
Cretaceous tectonic evolution of the Neo-Tethys in Central Iran:Evidence from petrology and age of the Nain-Ashin ophiolitic basalts 预览
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作者 Tahmineh Pirnia Emilio Saccani +3 位作者 Ghodrat Torabi Marco Chiari Spela Gorican Edoardo Barbero 《地学前缘:英文版》 CAS CSCD 2020年第1期57-81,共25页
The Nain and Ashin ophiolites consist of Mesozoic melange units that were emplaced in the Late Cretaceous onto the continental basement of the Central-East Iran microcontinent(CEIM).They largely consist of serpentiniz... The Nain and Ashin ophiolites consist of Mesozoic melange units that were emplaced in the Late Cretaceous onto the continental basement of the Central-East Iran microcontinent(CEIM).They largely consist of serpentinized peridotites slices;nonetheless,minor tectonic slices of sheeted dykes and pillow lavas-locally stratigraphically associated with radiolarian cherts-can be found in these ophiolitic melanges.Based on their whole rock geochemistry and mineral chemistry,these rocks can be divided into two geochemical groups.The sheeted dykes and most of the pillow lavas show island arc tholeiitic(IAT)affinity,whereas a few pillow lavas from the Nain ophiolites show calc-alkaline(CA)affinity.Petrogenetic modeling based on trace elements composition indicates that both IAT and CA rocks derived from partial melting of depleted mantle sources that underwent enrichment in subduction-derived components prior to melting.Petrogenetic modeling shows that these components were represented by pure aqueous fluids,or sediment melts,or a combination of both,suggesting that the studied rocks were formed in an arc-forearc tectonic setting.Our new biostratigraphic data indicate this arc-forearc setting was active in the Early Cretaceous.Previous tectonic interpretations suggested that the Nain ophiolites formed,in a Late Cretaceous backarc basin located in the south of the CEIM(the so-called Nain-Baft basin).However,recent studies showed that the CEIM underwent a counter-clockwise rotation in the Cenozoic,which displaced the Nain and Ashin ophiolites in their present day position from an original northeastward location.This evidence combined with our new data and a comparison of the chemical features of volcanic rocks from different ophiolites around the CEIM allow us to suggest that the Nain-Ashin volcanic rocks and dykes were formed in a volcanic arc that developed on the northern margin of the CEIM during the Early Cretaceous in association with the subduction,below the CEIM,of a Neo-Tethys oceanic branch that was existing between 展开更多
关键词 OPHIOLITE Volcanic arc Early Cretaceous Nain Ashin Iran
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安规测试仪用于塑料制品探伤检测 预览
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作者 蔡光跃 顾晶 罗加雷 《工业仪表与自动化装置》 2020年第1期73-75,共3页
该文介绍了传统的超声波、渗透和射线等绝缘体探伤方法,分析了它们的优缺点,针对其缺点,提出了用安规测试仪探伤塑料制品的方法。实验中,设置安规测试仪为拉弧停止,试验检测合格品的最高耐受电压,高压扫描塑料制品,筛选出不合格品。其... 该文介绍了传统的超声波、渗透和射线等绝缘体探伤方法,分析了它们的优缺点,针对其缺点,提出了用安规测试仪探伤塑料制品的方法。实验中,设置安规测试仪为拉弧停止,试验检测合格品的最高耐受电压,高压扫描塑料制品,筛选出不合格品。其过程简单、高效、快速、准确而且经济适用,可以通过改造测试探头适应不同的塑料制品,能取得不错的检测效果。 展开更多
关键词 安规测试仪 超声波 渗透 射线 拉弧 测试探头
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航空电气电弧、短路危害及保护研究 预览
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作者 曹涛 《航空工程进展》 CSCD 2020年第1期140-146,共7页
航空电气电弧、短路可能会导致难以挽回的损失,研究航空电气电弧、短路的危害及其保护措施具有重要意义。通过试验室搭建民用飞机典型的115 V/400 Hz三相交流电气线路,选取金属导体作为多余物,采用试验法对飞机电气电弧、短路故障现象... 航空电气电弧、短路可能会导致难以挽回的损失,研究航空电气电弧、短路的危害及其保护措施具有重要意义。通过试验室搭建民用飞机典型的115 V/400 Hz三相交流电气线路,选取金属导体作为多余物,采用试验法对飞机电气电弧、短路故障现象进行研究,验证和分析传统热断路器的工作特性,确认电气电弧、短路故障对电气线路和设备产生的危害程度;同时,分析三种更好的电气电弧、短路保护方法。结果表明:传统热断路器仅对短路故障具有保护作用,对电气电弧不能产生保护作用;三种新的保护方法电弧检测和保护时间过长,电弧已对导线和设备产品造成不可恢复的损坏。 展开更多
关键词 航空电气 电弧 短路 热断路器 SSPC
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基于GIS的高陵区土地生态状况评估 预览
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作者 杨彤 杨瑾 《农业与技术》 2020年第4期47-50,62,共5页
本文以高陵区乡镇作为评价单元,对其土地生态状况进行评估,通过对基础数据的整理分析,以土地自然条件指标、土地结构状况指标、生态保护指标、土地退化状况指标4个准则层为基础,包含7个评估指标、18个元指标,构建了高陵区土地生态状况... 本文以高陵区乡镇作为评价单元,对其土地生态状况进行评估,通过对基础数据的整理分析,以土地自然条件指标、土地结构状况指标、生态保护指标、土地退化状况指标4个准则层为基础,包含7个评估指标、18个元指标,构建了高陵区土地生态状况评估指标体系。借助GIS分析、景观格局分析、极差标准化法和熵值法等进行基础数据的处理及指标权重的测算。通过对生态状况的综合评估分值的计算,研究区可划分为优秀、良好、较差3个等级,优良等级占比近54. 28%,差的等级占比45. 72%,通过对优良、较差区域的分布情况的针对性分析,对生态状况较差的区域提出相关建议,这对高陵区生态环境的改善和保护有积极的意义。 展开更多
关键词 土地生态 Arc GIS 评估 高陵区
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受电弓过分段绝缘器电弧特性研究 预览
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作者 金文斌 《机械与电子》 2019年第2期35-39,共5页
受电弓通过分段绝缘器时,由于线路的不平整性,以及分段绝缘器自身结构特点,往往会产生电弧,且由于分段绝缘器两端存在数百上千伏高压,电弧往往难以熄灭,电弧停滞时间过长将对分段绝缘器造成烧蚀损伤,影响铁路安全运营。分段绝缘器中电... 受电弓通过分段绝缘器时,由于线路的不平整性,以及分段绝缘器自身结构特点,往往会产生电弧,且由于分段绝缘器两端存在数百上千伏高压,电弧往往难以熄灭,电弧停滞时间过长将对分段绝缘器造成烧蚀损伤,影响铁路安全运营。分段绝缘器中电弧的转移以及弧根的演变对其燃弧熄弧性能有重要影响。基于磁流体动力学理论(MHD),建立了受电弓过分段绝缘器空气电弧数学模型,通过对气压分布、受力大小、温度场、电压的分析,得到了受电弓过分段绝缘器弧根转移的根本原因。研究表明,电弧的转移主要是由于气流场和电磁力的作用,且电弧转移过程中对招弧角中段的烧蚀轻微,但由于电弧弧根到达顶端后停止大范围运动,使得招弧角顶端受烧蚀严重。 展开更多
关键词 分段绝缘器 电弧 弧根运动 电弧演变 温度场
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Fluctuation of arc plasma in arc plasma torch with multiple cathodes
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作者 张泽龙 王城 +1 位作者 孙强 夏维东 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第9期276-281,共6页
Fluctuation phenomena commonly exist in arc plasmas, limiting the application of this technology.In this paper,we report an investigation of fluctuations of arc plasmas in an arc plasma torch with multiple cathodes.Ti... Fluctuation phenomena commonly exist in arc plasmas, limiting the application of this technology.In this paper,we report an investigation of fluctuations of arc plasmas in an arc plasma torch with multiple cathodes.Time-resolved images of the plasma column and anode arc roots are captured.Variations of the arc voltage, plasma column diameter, and pressure are also revealed.The results indicate that two well-separated fluctuations exist in the arc plasma torch.One is the high-frequency fluctuation(of several thousand Hz), which arises from transferring of the anode arc root.The other is the low-frequency fluctuation(of several hundred Hz), which may come from the pressure variation in the arc plasma torch.Initial analysis reveals that as the gas flow rate changes, the low-frequency fluctuation shows a similar variation trend with the Helmholtz oscillation.This oscillation leads to the shrinking and expanding of the plasma column.As a result, the arc voltage shows a sinusoidal fluctuation. 展开更多
关键词 ARC FLUCTUATION ARC plasma HELMHOLTZ oscillation ANODE ARC root MULTIPLE cathodes
微型断路器灭弧失效分析及性能优化设计 预览
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作者 熊德智 陈向群 +2 位作者 杨杰 薛阳 张蓬鹤 《电工技术学报》 EI CSCD 北大核心 2019年第11期2333-2341,共9页
针对目前居民用微型断路器故障频发和灭弧能力严重不足的问题,开展微型断路器灭弧失效分析及性能优化研究。在分析微型断路器灭弧失效机理的基础上,提出优化设计技术路线图,建立微型断路器失效仿真模型,分析燃弧时间与栅片数量之间的关... 针对目前居民用微型断路器故障频发和灭弧能力严重不足的问题,开展微型断路器灭弧失效分析及性能优化研究。在分析微型断路器灭弧失效机理的基础上,提出优化设计技术路线图,建立微型断路器失效仿真模型,分析燃弧时间与栅片数量之间的关系,分析并给出模型关键优化参数的取值,对提出的4种设计方案进行仿真分析,得出最佳优化设计方案。通过对优化前、后的微型断路器样品进行实验分析可知,与优化前相比,试品优化后的分断时间和燃弧时间均显著减少,焦耳积分明显降低。实验结果与仿真结果相符,表明该优化设计方案可明显提升微型断路器的灭弧性能和分断能力,有效提高微型断路器的可靠性、安全性和稳定性,解决微型断路器灭弧失效的难题。 展开更多
关键词 微型断路器 电弧 灭弧栅 引弧片 优化
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Characteristics of non-thermal AC arcs in multi-arc generator
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作者 林启富 赵彦君 +5 位作者 段文学 倪国华 靳兴月 隋思源 谢洪兵 孟月东 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第12期255-267,共13页
To obtain large-volume non-thermal arc plasma(NTAP), a multiple NTAP generator with three pairs of electrodes has been developed. The arc plasma characteristics, including dynamic process, spatial distribution, and ro... To obtain large-volume non-thermal arc plasma(NTAP), a multiple NTAP generator with three pairs of electrodes has been developed. The arc plasma characteristics, including dynamic process, spatial distribution, and rotation velocity in the discharge zone, were investigated by high speed photograph and image processing methods. The results showed that the dynamic behaviors and spatial distribution of the arc plasma were strongly related to the electrode configuration.A swirl flow of multi-arc plasma was formed by adjusting the electrode configuration, and a steady luminance area was clearly observed in the center of the discharge zone. Moreover, the size of the luminance area increased by decreasing the gas flow rate. The electrical connection in series could be formed between/among these arc columns with their respective driving power supplies in the multi-arc dynamic evolution process. An approximately periodical process of acceleration and deceleration of the arc rotation velocity was observed in the multi-arc generator with swirl flow configuration. In general, the mean velocity of arc rotation was higher in the multi-arc generator with swirl flow configuration when a pair of electrodes driven by a power supply were opposite to each other rather than adjacent. 展开更多
关键词 CHARACTERISTICS multiple arc plasma multi-arc generator non-thermal arc
电弧填丝增材制造过程熔滴射滴过渡特征及其对熔滴沉积成形的影响
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作者 罗怡 朱亮 +2 位作者 韩静韬 许洁 张成洋 《机械工程学报》 EI CAS CSCD 北大核心 2019年第3期219-225,共7页
基于脉冲GMA电弧检测了电弧填丝增材制造过程中与熔滴过渡相关的电弧电流、电弧电压和声发射信号,研究了电弧脉冲作用下的铝合金熔滴射滴过渡特征,提出了一种可对处于射滴过渡模式下的熔滴尺寸、电弧力和熔滴沉积率进行计算的方法,并分... 基于脉冲GMA电弧检测了电弧填丝增材制造过程中与熔滴过渡相关的电弧电流、电弧电压和声发射信号,研究了电弧脉冲作用下的铝合金熔滴射滴过渡特征,提出了一种可对处于射滴过渡模式下的熔滴尺寸、电弧力和熔滴沉积率进行计算的方法,并分析了沉积层的成形质量特征。研究结果表明,利用检测获得的电弧电压、电弧电流信号和声发射信号可以对处于射滴过渡模式下的熔滴过渡过程及其特征进行区分。在本研究条件下,作用在过渡熔滴上的电弧力随电弧功率增加而递增。电弧力的增加将限制熔滴尺寸的增大,从而在电弧功率递增时呈现熔滴尺寸的递减和熔滴过渡频率的递增。同时,电弧功率增加,使热输入增大,射滴过渡熔滴对熔池的冲击增强,容易造成熔滴过渡形成的沉积层坍塌,从而使熔滴沉积层高度递增的趋势减缓,形成的沉积层显微组织明显粗化。 展开更多
关键词 增材制造 电弧 熔滴过渡 电弧信号 制造效率
糖尿病大鼠下丘脑ARC Ghrelin/Obestatin信号改变及对胃运动和摄食的影响 预览
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作者 郜慧英 金婷婷 +3 位作者 郭菲菲 高胜利 刘潇柠 孙向荣 《菏泽医学专科学校学报》 2019年第3期1-6,共6页
目的观察Ghrelin/Obestatin在链脲佐菌素(STZ)所致糖尿病大鼠下丘脑弓状核(ARC)表达的改变及对胃运动和摄食的影响。方法免疫组化方法观察糖尿病大鼠下丘脑ARC中Ghrelin/Obestatin表达的改变;单细胞放电观察Ghrelin/Obestatin对大鼠下丘... 目的观察Ghrelin/Obestatin在链脲佐菌素(STZ)所致糖尿病大鼠下丘脑弓状核(ARC)表达的改变及对胃运动和摄食的影响。方法免疫组化方法观察糖尿病大鼠下丘脑ARC中Ghrelin/Obestatin表达的改变;单细胞放电观察Ghrelin/Obestatin对大鼠下丘脑ARC内胃扩张敏感(GD)神经元放电活动的影响;在体胃运动研究观察下丘脑ARC注射Ghrelin/Obestatin对大鼠胃运动影响;观察下丘脑ARC注射Ghrelin/Obestatin对大鼠摄食的影响。结果大鼠下丘脑ARC内分布有Ghrelin/Obestatin免疫阳性细胞。与正常大鼠相比,糖尿病大鼠下丘脑ARC内Ghrelin免疫阳性细胞数目显著增加,Obestatin免疫阳性细胞数目显著减少;Ghrelin能够兴奋下丘脑ARC内GD-E神经元、抑制GD-I神经元,Obestatin能够抑制下丘脑ARC内GD-E神经元、兴奋GD-I神经元。与正常大鼠相比,Ghrelin对糖尿病大鼠GD神经元的作用显著增强,Obestatin对GD神经元的作用显著减弱;下丘脑ARC微量注射Ghrelin可促进大鼠胃运动、摄食,与正常大鼠相比,Ghrelin对糖尿病大鼠胃运动、摄食的促进作用显著增强,下丘脑ARC微量注射Obestatin可抑制大鼠胃运动及摄食,与正常大鼠相比,Obestatin对糖尿病大鼠胃运动及摄食的抑制作用显著减弱。结论糖尿病大鼠下丘脑ARC Ghrelin信号增强而Obestatin信号减弱。这两条信号通路参与糖尿病大鼠胃运动及摄食的调节。该效应分别由Ghrelin受体和促肾上腺皮质激素释放激素受体-1(CRFR1)介导。 展开更多
关键词 OBESTATIN GHRELIN 下丘脑ARC 胃运动 摄食 糖尿病
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Numerical simulation of constricted and diffusive arc-anode attachments in wall-stabilized transferred argon arcs
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作者 朱涛 王海兴 +2 位作者 孙素蓉 耿金越 沈岩 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第12期57-66,共10页
A numerical simulation is conducted to investigate arc-anode attachment behavior, especially the formation mechanism of the constricted arc attachment mode for the water-cooled anode of wall-stabilized transferred arg... A numerical simulation is conducted to investigate arc-anode attachment behavior, especially the formation mechanism of the constricted arc attachment mode for the water-cooled anode of wall-stabilized transferred argon arcs. Argon molecular ions and the corresponding kinetic processes are included to the finite-rate chemistry model in order to capture the chemical nonequilibrium characteristics of the arc near the anode region. Modeling results show that constricted and diffusive arc–anode attachments can be self-consistently obtained at different arc currents while keeping other parameters unchanged. The dominant kinetic processes contributing to ionization and recombination in the arc center and fringes are presented. The results show that in arc fringes and the arc attachment region, molecular ion recombination plays an important role which leads to the rapid loss of electrons. The radial evolution of the production, loss and transport processes of electrons is further analyzed. It is found that for the constricted arc attachment mode, both the recombination and convection transport caused by the anode jet result in the loss of electrons at the arc fringes, which leads to the shrinkage of the arc column at the anode. The formation of the anode jet is due to the combined action of radial and axial Lorentz forces in the anode region. 展开更多
关键词 DC transferred arc arc attachment mode chemical nonequilibrium
心脏瓣膜病中线粒体凋亡调控因子与microRNA的相互作用
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作者 尹波 李翠翠 +1 位作者 朱应超 刘公哲 《基因组学与应用生物学》 CAS CSCD 北大核心 2019年第9期4314-4318,共5页
为了揭示心脏瓣膜病中线粒体凋亡调控因子与microRNA的相互作用,本研究检测了心脏瓣膜病患者瓣膜组织病变部位和周围健康组织中的线粒体凋亡调控因子PUMA、Drp1和ARC的表达,并分析了病变部位的ROS水平和SOD活性,同时考察了miR-214和miR-... 为了揭示心脏瓣膜病中线粒体凋亡调控因子与microRNA的相互作用,本研究检测了心脏瓣膜病患者瓣膜组织病变部位和周围健康组织中的线粒体凋亡调控因子PUMA、Drp1和ARC的表达,并分析了病变部位的ROS水平和SOD活性,同时考察了miR-214和miR-15a对凋亡因子PUMA和ARC的影响。研究显示,PUMA和Drp1在病变组织中表达水平显著升高,而ARC表达显著降低(p<0.05)。病变组织中ROS水平显著升高,而SOD活性显著降低(p<0.05)。瓣膜组织病变部位的miR-214表达水平显著升高,而miR-15a显著降低(p<0.05)。应用miRNA抑制剂下调miR-214和miR-15a后,PUMA和ARC的表达水平被显著上调(p<0.05)。本研究表明在心脏瓣膜病患者中,miR-214和miR-15a分别靶向ARC和PUMA。 展开更多
关键词 心脏瓣膜病 凋亡 miR-214 miR-15a ARC PUMA
Study on volt-ampere characteristics of solar array arcs in LEO spacecraft
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作者 朱立颖 刘治钢 +3 位作者 张晓峰 王超 李小飞 赵冰欣 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第2期39-46,共8页
The primary and secondary arcs volt-ampere characteristics of low earth orbit solar arrays are studied in this research. Using three gallium-arsenide solar cell samples, the gap lengths of the solar cell are set to 1,... The primary and secondary arcs volt-ampere characteristics of low earth orbit solar arrays are studied in this research. Using three gallium-arsenide solar cell samples, the gap lengths of the solar cell are set to 1, 2, and 3 mm. First, the primary arc voltage characteristics of a solar array are analyzed. It is found that two steps are involved in the primary arc voltages, which are 116 and 22 V according to our experiment and are independent of the electrostatic discharge current and the gap lengths. By comparing with the arc pattern, we determined that current chopping may be the reason for the stepped arc voltage. Then, the characteristics of the secondary arc of the solar array are demonstrated. The study shows that the secondary arc voltage values increase with the gap length. In the case of the same cell with a fixed gap length, the voltage of the secondary arc increases with the string current. Finally, the relationship between the secondary arc voltage and the gap length is obtained which helps the string voltage and the gap length selection for system design. 展开更多
关键词 primary ARC SECONDARY ARC solar ARRAY
偶氮二异庚腈的热分解动力学研究 预览
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作者 郭心怡 潘惠泉 +3 位作者 王顺尧 陈利平 饶国宁 陈网桦 《安全与环境工程》 CAS 北大核心 2019年第4期165-170,共6页
为获得准确的偶氮二异庚腈(ABVN)的热分解动力学模型及其动力学参数,利用差示扫描量热仪(DSC)和绝热量热仪(ARC)对ABVN在动态和绝热条件下的热分解特性进行测试。由于ABVN是一种吸放热耦合的物质,因而采用AKTS软件对其进行解耦。联合采... 为获得准确的偶氮二异庚腈(ABVN)的热分解动力学模型及其动力学参数,利用差示扫描量热仪(DSC)和绝热量热仪(ARC)对ABVN在动态和绝热条件下的热分解特性进行测试。由于ABVN是一种吸放热耦合的物质,因而采用AKTS软件对其进行解耦。联合采用解耦后的动态和绝热两种量热模式下的试验数据对ABVN进行热分解动力学分析,建立了N级分解动力学模型,并采用Friedman方法和非线性拟合方法求算其热分解动力学参数。联合动态和绝热两种量热模式下试验数据的拟合结果表明:N级分解动力学模型拟合得到的拟合曲线与试验曲线基本吻合,说明该模型可以很好地反映ABVN的热分解过程,其活化能为98.31kJ/mol,指前因子为3.3×10^15,反应级数为1.18。最后利用中断回扫法进一步验证了建立的ABVN热分解动力学模型的正确性。基于ABVN热分解动力学模型获得的热分解动力学参数对ABVN的生产、运输、存储等过程具有一定的安全指导意义。 展开更多
关键词 偶氮二异庚腈 热分解 动力学 DSC ARC
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中老年期CD-1小鼠海马突触蛋白Arc含量改变及其与认知功能下降的相关性研究
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作者 张折折 吴永芳 +3 位作者 李学伟 曹磊 陈贵海 王芳 《安徽农业大学学报》 CAS CSCD 2019年第3期405-409,共5页
探究中老年CD-1小鼠海马突触蛋白Arc含量的改变及其与空间学习记忆能力下降的相关性。选取3月龄和15月龄CD-1小鼠各10只(雌雄各半),用Morris水迷宫和免疫组织化学法分别检测其空间学习记忆能力和海马Arc蛋白相对含量。与3月龄相比,15月... 探究中老年CD-1小鼠海马突触蛋白Arc含量的改变及其与空间学习记忆能力下降的相关性。选取3月龄和15月龄CD-1小鼠各10只(雌雄各半),用Morris水迷宫和免疫组织化学法分别检测其空间学习记忆能力和海马Arc蛋白相对含量。与3月龄相比,15月龄鼠在Morris水迷宫学习期游泳路程延长(F(1,16)=5.338, P<0.05),记忆期靶象限内游泳路程百分比下降(F(1,16)=78.013, P<0.01),海马CA1和CA3区Arc水平增加(P<0.05)。相关分析显示15月龄鼠海马CA1、CA3和DG区Arc相对含量与学习期游泳路程正相关(P<0.05),CA3、DG区Arc含量还与记忆期靶象限游泳路程百分比负相关(P<0.05)。中老年CD-1小鼠海马Arc含量呈亚区特异性增高,可能涉及其空间学习记忆损害。 展开更多
关键词 小鼠 衰老 Arc蛋白 学习记忆
Analysis of Electrical Characteristics of Inter-wire Arc in Cross-Coupling Arc 预览
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作者 Zhenyang Lu Shanwen Dong +1 位作者 Fan Jiang Cheng Li 《中国机械工程学报:英文版》 SCIE EI CAS CSCD 2019年第2期203-211,共9页
As a new composite welding heat source introduced in recent years, the cross-coupling arc uses a non-consumable electrode arc(plasma arc) and a consumable electrode arc(inter-wire arc) in cross-coupling, in which the ... As a new composite welding heat source introduced in recent years, the cross-coupling arc uses a non-consumable electrode arc(plasma arc) and a consumable electrode arc(inter-wire arc) in cross-coupling, in which the plasma arc is the main arc and the inter-wire arc is the vice arc, to realize the separate control of the heat input to the workpiece,arc force, and droplet transfer. To reveal the electrical characteristics of the inter-wire arc under the action of the plasma arc, in this study, rotating probes are used to sweep across the plasma arc. When the probes rotate into the plasma arc, a circuit is formed, and the electrical characteristics of the inter-wire arc are indirectly analyzed according to the circuit: the probe centering current and input voltage are used as the physical quantities. The results show that at a certain wire feed rate, the inter-wire arc current increases with increasing input voltage. When the input voltage is low, the wire feed rate has no obvious e ect on the inter-wire arc current. At a higher input voltage, where the wire feed rate is high, the inter-wire arc current decreases. With the increase in the plasma arc current, the inter-wire arc current first increases quickly and then increases slowly, and simultaneously, the striking arc time becomes longer.With the increase in the interval between the nozzle and the workpiece, the inter-wire arc current increases, but when the arc length increases to a certain limit, the slope of the welding current clearly declines. 展开更多
关键词 Inter-wire ARC Circuit INPUT VOLTAGE Inter-wire ARC current
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Effect of fusion welding processes on tensile properties of armor grade, high thickness, non-heat treatable aluminium alloy joints 预览
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作者 K. Vasu H. Chelladurai +2 位作者 Addanki Ramaswamy S. Malarvizhi V. Balasubramanian 《Defence Technology(防务技术)》 CAS CSCD 2019年第3期353-362,共10页
AA5059 is one of the high strength armor grade aluminium alloy that finds its applications in the military vehicles due to the higher resistance against the armor piercing (AP) threats. This study aimed at finding the... AA5059 is one of the high strength armor grade aluminium alloy that finds its applications in the military vehicles due to the higher resistance against the armor piercing (AP) threats. This study aimed at finding the best suitable process among the fusion welding processes such as gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) by evaluating the tensile properties of AA5059 aluminium alloy joints. The fracture path was identified by mapping the low hardness distribution profile (LHDP) across the weld cross section under tensile loading. Optical and scanning electron microscopies were used to characterize the microstructural features of the welded joints at various zones. It is evident from the results that GTAW joints showed superior tensile properties compared to GMAW joints and this is primarily owing to the presence of finer grains in the weld metal zone (WMZ) and narrow heat-affected zone (HAZ). The lower heat input associated with the GTAW process effectively reduced the size of the WMZ and HAZ compared to GMAW process. Lower heat input of GTAW process results in faster cooling rate which hinders the grain growth and reduces the evaporation of magnesium in weld metal compared to GMAW joints. The fracture surface of GTAW joint consists of more dimples than GMAW joints which is an indication that the GTAW joint possess improved ductility than GMAW joint. 展开更多
关键词 GAS tungsten ARC WELDING GAS metal ARC WELDING ARMOR GRADE aluminium alloy TENSILE properties Microhardness
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振动加载下转换型密封电磁继电器的性能退化行为研究 预览
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作者 朱蒙 李明 李刚 《装备环境工程》 CAS 2019年第3期43-48,共6页
目的研究航空用继电器的失效机理。方法通过对电磁继电器进行振动与工作载荷单独施加以及二者综合加载情况下的试验方法及性能退化行为研究,实时监测继电器内部触点间接触电阻等性能参数的变化趋势,并对不同条件下触点表面的微观形貌进... 目的研究航空用继电器的失效机理。方法通过对电磁继电器进行振动与工作载荷单独施加以及二者综合加载情况下的试验方法及性能退化行为研究,实时监测继电器内部触点间接触电阻等性能参数的变化趋势,并对不同条件下触点表面的微观形貌进行对比分析。结果发现相比较工作载荷单独施加而言,振动应力的加入使得继电器的寿命大幅度降低,并使得触点表面呈现'雪花'一般的形貌。结论振动环境导致了触点之间电弧的变化,以及触点表面接触压力、接触面积和接触超程等,并通过燃弧时间和超程时间的变化趋势对其进行了验证。 展开更多
关键词 寿命 电弧 性能退化 接触电阻 燃弧时间 超程时间
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