Current Situation and Discussion of “Going Abroad” in Higher Vocational Colleges Under the Background of the Belt and Road Initiative

The Belt and Road Initiative has brought unprecedented development opportunities for domestic higher vocational colleges to“go abroad,”but it has also brought severe challenges.Driven by the Belt and Road Initiative,the development of higher vocational colleges“going abroad”has been confronted with a series of challenges,including the imperfect connection of policies,the lack of internal funds,as well as international standards,which are important factors affecting their development.Therefore,it is necessary to start from three aspects,which are policy guarantee,financing,and docking international standards.Through in-depth study of“going abroad”with tthe Belt and Road Initiative,we can effectively reduce the adverse impact of“going abroad”and provide a better and more innovative development environment for higher vocational colleges.

Effects of drive current rise-time and initial load density distribution on Z-pinch characteristics

A two-dimensional, three-temperature radiation magneto-hydrodynamics model is applied to the investigation of evolutional trends in x-ray radiation power, energy, peak plasma temperature and density as functions of drive current rise-time and initial load density distribution by using the typical experimental parameters of tungsten wire-array Z- pinch on the Qiangguang-I generator. The numerical results show that as the drive current rise-time is shortened, x-ray radiation peak power, energy, peak plasma density and peak ion temperature increase approximately linearly, but among them the x-ray radiation peak power increases more quickly. As the initial plasma density distribution in the radial direction becomes gradually flattened, the peak radiation power and the peak ion-temperature almost exponentially increase, while the radiation energy and the peak plasma density change only a little. The main effect of shortening drive current rise-time is to enhance compression of plasma, and the effect of flattening initial load density distribution in the radial direction is to raise the plasma temperature. Both of the approaches elevate the x-ray peak radiation power

Spontaneous local redox reaction to passivate CNTs as lightweight current collector for high energy density lithium ion batteries

Extensive usage of highly conductive carbon materials with large specific surface area(e.g.,carbon nanotubes,CNTs)in lithium ion batteries(LIBs),especially as current collector of anodes,suffers from low initial coulombic efficiency(ICE),large interfacial resistance,and severe embrittlement,as the large specific surface area often results in severe interfacial decomposition of the electrolyte and the formation of thick and fluffy solid electrolyte interphase(SEI)during cycling of LIBs.Herein,we demonstrate that when the CNT-based current collector and Na foil(which are being stacked intimately upon each other)are being placed in Na+-based organic electrolyte,local redox reaction between the Na foil and the electrolyte would occur spontaneously,generating a thin and homogeneous NaF-based passivating layer on the CNTs.More importantly,we found that owing to the weak solvation behaviors of Na+in the organic electrolyte,the resulting passivation layer,which is rich in NaF,is thin and dense;when used as the anode current collector in LIBs,the pre-existing passivating layer can function effectively in isolating the anode from the solvated Li+,thus suppressing the formation of bulky SEI and the destructive intercalation of solvated Li+.The relevant half-cell(graphite as anode)exhibits a high ICE of 92.1%;the relevant pouch cell with thus passivated CNT film as current collectors for both electrodes(LiCoO_(2)as cathode,graphite as anode)displays a high energy density of 255 Wh kg^(-1),spelling an increase of 50%compared with that using the conventional metal current collectors.

Origin of Initial Current Peak in High Power Impulse Magnetron Sputtering and Verification by Non-Sputtering Discharge

A non-sputtering discharge is utilized to verify the effect of replacement of gas ions by metallic ions and consequent decrease in the secondary electron emission coefficient in the discharge current curves in high-power impulse magnetron sputtering （HiPIMS）. In the non-sputtering discharge involving hydrogen, replacement of ions is avoided while the rarefaction still contributes. The initial peak and ensuing decay disappear and all the discharge current curves show a similar feature as the HiPIMS discharge of materials with low sputtering yields such as carbon. The results demonstrate the key effect of ion replacement during sputtering.

触发闪电环境下地网冲击接地电阻特征分析

基于触发闪电技术,研究了2019年夏季8次触发闪电44次回击、5次初始连续电流脉冲(ICCP)和24次M分量对冲击接地电阻的影响,探索了冲击接地电阻随雷电流注入的动态变化规律。结果发现:闪电放电ICCP、M分量和回击过程冲击接地电阻均小于工频接地电阻,ICCP和叠加在回击回落之后连续电流上的M分量冲击接地电阻略大于回击过程,平均值分别为11.2Ω和10.8Ω。叠加在回击下降沿上的M分量冲击接地电阻平均值7.8Ω,明显小于回击过程,最小值可达2.4Ω。ICCP和M分量冲击接地电阻随电流增加而减小,回击过程与电流峰值没有明显的相关性。叠加在回击下降沿上的M分量冲击接地电阻随雷电流峰值、背景电流值的增加呈指数衰减关系,还与之前回击电流峰值成一定的反比例关系。随着闪电回击电流的注入,冲击接地电阻呈现动态变化过程,小电流在回击峰值下降后出现一个缓慢增长的过程,大电流在回击峰值下降后出现一个快速下降的过程。闪电不同物理过程火花和电感效应的作用是不同的,两者共同作用决定了土壤的电离程度,从而决定了冲击接地电阻的大小和变化。

基于密绕小直径线圈的磁感应透地无线起爆系统性能分析

为了在矿区开采时实现安全便携的透地无线起爆,提出了地上发射端采用密绕小直径线圈的磁感应透地无线起爆方案,并建立了地面发射线圈与地下接收线圈等效耦合电路分析模型,推导了地下接收端负载的电压表达式,用地面发射线圈与地下接收线圈间的互感系数表征了收发线圈间耦合强度的大小。由于地面发射线圈与地下接收线圈间的相对位置关系不是平行共轴,传统基于平行且共轴线圈的互感公式不再适用,本文从磁矢位出发推导出了考虑涡流效应的具有一般位置关系的单匝圆线圈间互感系数的通用表达式。由于地面发射线圈采用横放模式存在爆破盲区,地面发射线圈应采用竖放模式。基于负载电压公式分析了发射线圈半径与匝数、发射信号频率和垂直透地深度对透地起爆系统地下接收端负载电压和水平覆盖距离的影响。仿真结果表明:发射线圈采用竖放模式的透地无线起爆系统的水平覆盖距离可达到200~300m;随着透地深度的增加,系统的水平覆盖距离逐渐降低,但可以通过适当增加发射线圈半径和匝数、降低发射信号频率的方式提高透地无线起爆系统的水平覆盖距离,以满足在不同规模矿区开采应用场景下的透地无线起爆需求。

大环发射天线磁感应透地无线起爆系统透地性能分析

为在露天矿等起爆作业场景中实现大规模的透地无线起爆,研究在地上发射端采用大环发射天线的磁感应透地无线起爆系统。建立磁感应透地无线起爆中发射天线线圈与接收天线线圈的等效电路,基于等效电路建立大环形天线无线起爆透地磁感应强度模型,计算得到透地无线起爆磁感应强度阈值。仿真分析透地深度、发射天线匝数与半径、发射功率等因素对透地磁感应强度的影响。研究结果表明:透地无线起爆系统能实现对地下7.52m深处雷管的起爆,且可通过增加发射线圈匝数、适当降低发射线圈半径,以及提高发射功率的方式提高透地无线起爆系统的起爆深度。研究结论为大环形发射天线磁感应透地无线起爆系统的参数选取提供理论依据。

基于双端初始电流行波时频矩阵相似度的柔性直流输电线路保护原理

针对目前柔性直流(voltage source converter-based high voltage DC,VSC-HVDC)电网的线路保护中存在的问题,提出一种基于双端初始电流行波(Initial current traveling wave,ICTW)时频矩阵相似度的柔性直流输电线路保护原理。首先,对柔性直流电网在线路区内外故障下两端保护所在处ICTW的故障特性进行分析,总结出在特定时间窗内,区内故障下两端ICTW的频域相似度远高于区外故障。在此基础上,利用S变换对双端ICTW进行时频分析,建立时频矩阵,并对其做奇异值分解(singular value decomposition,SVD)。然后根据特征矩阵构造双端ICTW的相似度计算公式,以该相似度的大小判别线路区内外故障。另外,根据线路两端ICTW的高低频能量比识别雷击干扰。最后,各种故障情况下的仿真结果表明,该保护原理不依赖线路边界元件,可以保护不同长度线路的全长,具有更高的耐过渡电阻和抗噪声能力,并且能够满足柔性直流电网主保护的速动性要求。

“一带一路”倡议下哈萨克斯坦高校汉语教育现状及特点分析--以阿布莱汗国际关系与外国语大学为例

哈萨克斯坦阿布莱汗国际关系与外国语大学是哈萨克斯坦汉语教学的成功典范,通过考察当前该校汉语师资概况,发现该校汉语教学呈现“教研学培一体化师资培养”“语言服务特征突出的孔院建设”“兼具工具性与人文性的课程设置”的特征。结合相关文献,与十年前《阿布莱汗国际关系与外国语大学的汉语教学现状与存在的问题》一文进行对话,得知十年前阿布莱汗国际关系与外国语大学汉语教育中存在的教材与大纲脱节,标音、翻译不规范,哈萨克斯坦师生赴华进修、实习机会少,中方汉语师资支援不足等问题在当前都得到了不同程度的解决。目前哈方汉语教学中尚未解决的问题及新涌现的挑战将随着中哈合作交流不断深入在双方共同努力下得到解答。

河南汤阴方言古知庄章组声母的今读及演变

今天的汤阴方言中,古知庄章组声母与精组洪音声母合流,读为[■]或[■]。结合周边方言的共时考察,可以发现,汤阴方言知庄章组与精组洪音合一,是在知庄章组开合口归为一组并与精组对立的前提下演变而来的。通过梳理《中原音韵》《青郊杂著》《交泰韵》等韵书知庄章组声母的情况,大致确定知庄章组声母合一发生在明代。汤阴方言知庄章精(洪)组声母合一,可能是因为受到了周边合一型方言的影响。

龙源新解

现在一般认为,龙是人类想象的产物,龙的原型是鱼类、爬行动物结合某些天象而形成的。但该文认为龙的源头在于水,水是动物所必需的,龙与水不能分离。龙乃水之物,是泉瀑之类条形水的升华与神化。龙能幽能显、能短能长的外形活动,与水流的明暗延曲有关,龙字的发音来源悬瀑涌泉的“隆隆”之声。水部中,与龙同一声母且同韵近韵的字大多有水的撞击、奔流之义。以“龙”作为声旁的一些字词,都有收束、聚集、条形性集中的内涵。经笔者长期探索,认为龙最基本、最原始的形象是水,是泉瀑一类特殊的水。水是生命之源,是生存的必需,最贴近人的生活,把泉瀑之类的条形水,想象为龙并不奇怪。

Modeling of Propagation and Transformation of Transient Nonlinear Waves on A Current

A novel theoretical approach is applied to predict the propagation and transformation of transient nonlinear waves on a current. The problem was solved by applying an eigenfunction expansion method and the derived semi-analytical solution was employed to study the transformation of wave profile and the evolution of wave spectrum arising from the nonlinear interactions of wave components in a wave train which may lead to the formation of very large waves. The results show that the propagation of wave trains is significantly affected by a current. A relatively small current may substantially affect wave train components and the wave train shape. This is observed for both opposing and following current. The results demonstrate that the application of the nonlinear model has a substantial effect on the shape of a wave spectrum. A train of originally linear and very narrow-banded waves changes its one-peak spectrum to a multi-peak one in a fairly short distance from an initial position. The discrepancies between the wave trains predicted by applying the linear and nonlinear models increase with the increasing wavelength and become significant in shallow water even for waves with low steepness. Laboratory experiments were conducted in a wave flume to verify theoretical results. The free-surface elevations recorded by a system of wave gauges are compared with the results provided by the nonlinear model. Additional verification was achieved by applying a Fourier analysis and comparing wave amplitude spectra obtained from theoretical results with experimental data. A reasonable agreement between theoretical results and experimental data is observed for both amplitudes and phases. The model predicts fairly well multi-peak spectra, including wave spectra with significant nonlinear wave components.

Steady Lateral Growth of Three-Dimensional Particle Laden Density Currents

In this paper the steady lateral growth of three-dimensional turbulent inclined turbidity current is investigated. To simulate the current, an experimental setup is developed to analyze the turbidity current for different regimes in the particle laden density currents environment. The Buckingham’s π theorem together with a dimensional analysis is implemented to derive the appropriate non-dimensional variables. The experimental results were normalized and plotted in the form of non-dimensional graphs from which a theoretical model is developed and analyzed. Based on the results obtained for the steady lateral growth, three different regimes, namely, inertia-viscous one as the first regime, buoyancy-viscous and gravity-viscous as the second and third regimes are distinguished within the current.In these regimes, the force balance is between the driving and resisting forces. Namely, in the first regime, the force balance is between the inertia and viscous forces, in the second regime, the buoyancy and viscous forces, and in the third regime, gravity and viscous forces are balanced. The experimental results indicate that the lateral growth rate in the first regime is smaller than that in the second and third regimes due to the magnitude and type of the forces involved in those regimes. According to the graphical results, the three different lateral growth rates appear when the normalized current length is smaller than about 3, between about 3 and 10, and larger than about 10. In those regions,the slopes of the data are different with respect to one another.

Influence of Jet Angle and Ion Density of Cathode Side on Low Current Vacuum Arc Characteristics

In this study, the influence of the initial jet angles （IJAs） and ion number densities （INDs） at the cathode side on the low current vacuum arc （LCVA） characteristics is simulated and analysed. The results show that the ion temperature, electron temperature, ion number density, axial current density and plasma pressure all decrease with the increase of the cathode IJAs. It is also shown that LCVA can cause a current constriction for lower cathode IND, and the anode sheath potential is more nonuniform, which is mainly related to the nonuniform distribution of the axial current density at the anode side.

Effect of actuating frequency on plasma assisted detonation initiation

Aiming at studying the influence of actuating frequency on plasma assisted detonation initiation by alternating current dielectric barrier discharge, a loosely coupled method is used to simulate the detonation initiation process of a hydrogenoxygen mixture in a detonation tube at different actuating frequencies. Both the discharge products and the detonation forming process which is assisted by the plasma are analyzed. It is found that the patterns of the temporal and spatial distributions of discharge products in one cycle are not changed by the actuating frequency. However, the concentration of every species decreases as the actuating frequency rises, and atom O is the most sensitive to this variation, which is related to the decrease of discharge power. With respect to the reaction flow of the detonation tube, the deflagration-todetonation transition（DDT） time and distance both increase as the actuating frequency rises, but the degree of effect on DDT development during flow field evolution is erratic. Generally, the actuating frequency affects none of the amplitude value of the pressure, temperature, species concentration of the flow field, and the combustion degree within the reaction zone.

爆炸箔1A1min及最大不损坏电流试验方法研究

针对爆炸箔起爆器抗直流电流能力和意外受到射频敏感特性的相关问题,建立了爆炸箔1A1min及最大不损坏电流试验方法,开展了不同基底结构的爆炸箔1A1min不损坏电流以及最大不损坏电流试验验证。试验结果表明:采用本试验方法可以有效地测试爆炸箔起爆器1A1min不损坏电流值及最大不损坏电流值;爆炸箔在经历1A1min不损坏电流试验前后的桥区几乎没有发生任何变化,且试验后其功能正常、作用可靠;对于聚酰亚胺基底的爆炸箔,当加载电流值越接近最大不损坏电流值时,桥区反应颜色越深;对于陶瓷基底的爆炸箔,当施加电流小于最大不损坏电流时,桥区颜色几乎未发生明显变化;两种不同基底结构的爆炸箔在经历最大不损坏电流试验后,桥区的电阻和电感参数均未发生明显变化,均在测试误差±10mΩ和±10nH范围之内。

海拔2200m地区正极性操作冲击下大尺寸球–板间隙放电转化特性

在我国中西部海拔超2000m地区,曲率半径达0.25~1m的屏蔽球金具在特高压直流输电换流站阀厅中应用广泛,其与地面、墙壁形成的球–板间隙直接影响整个输电系统的绝缘安全及经济成本,因此研究高海拔地区大尺寸球–板长间隙放电转化特性具有重要的理论意义和工程价值。该文在海拔2200m的青海特高压试验基地开展3m间隙距离下,曲率半径为0.30、0.65、0.80m的球–板间隙正极性操作冲击放电试验;对比分析3种电极结构各放电阶段的瞬时光功率、空间电场强度、高电位电流等光电特征物理参量;计算其初始流注注入电荷量、电场强度空间分布、初始流注长度、流注茎温度等物理特征值;研究间隙结构对大尺寸电极放电转化特性的影响。结果表明:间隙距离一致,球电极曲率半径越大时,初始流注长度越长、产生空间电荷量越多、流注茎温度上升速率越快、流注逐渐成为放电过程的主导。研究结果可为今后高海拔地区换流站阀厅选择合适的屏蔽结构、有效增强间隙操作冲击绝缘水平及减小设备尺寸等提供参考。

从丝绸之路到一带一路:纵观中伊医疗交流的历史、现状与未来

丝绸之路东起西汉古都长安(今陕西西安),绵延数千公里,驼铃相闻,途径中亚、西亚进而到达欧洲和北非地区。其上下跨越2000多年,搭建起了中国与丝绸之路沿线国家文化、政治、经济、宗教等交流与互动的桥梁,是不同文明间相互吸引、交融,求同存异的见证,具有深刻的历史意义。2013年我国提出“一带一路”倡议,进一步推动了我国与古丝绸之路沿线国家的文化交流。该文通过概述自古而今中国与伊朗两国凭借丝绸之路与“一带一路”倡议为载体而实现的医药领域的交流与合作,初步探索中伊未来医疗合作的新机遇、新模式,这在高度重视医疗卫生发展与全民健康,倡导国际合作的当今社会具有一定的理论意义。

适应电流差动保护的光伏电站边界接入容量分析

光伏电站在电网中的占比持续增加,使得电网的短路电流呈现幅值受限、初相角受控的特征,导致区内故障下差动电流大于制动电流的特有关系不再成立,传统电流差动保护将出现不正确动作风险。文章首先基于光伏发电单元故障响应特性,构建了光伏电站短路电流幅值与初相角的数学模型;然后,通过分析光伏电站接入容量变化对送出线路两侧制动电流与差动电流比值的影响规律,进一步推导获得了适应差动保护的光伏电站边界接入容量解析表达式;最后,利用PSCAD/EMTDC仿真试验,证明了文章所提边界接入容量的计算表达式,以及在评价含光伏电站电网的传统差动保护适应性等方面的有效性。