Crystallochemical Characterizations, Raman Spectroscopy and Studies Nuclear Magnetic Resonance (NMR) of Cu₂Zn(Sn, Si)S₄Compounds for Photovoltaic Applications

In this study, Si-doped Cu2ZnSnS4 compounds (Cu2ZnSn1-xSixS4, 0 ≤ x ≤ 1) were prepared by solid state reaction method for use of materials for photovoltaic cells. The structural and spectroscopic properties of the as-prepared compounds were studied by X-ray diffraction (XRD), 119Sn, 29Si and 65Cu Magic Angle Spinning nuclear magnetic resonance (MAS NMR) and Raman spectroscopy. The Si-substitution in the Sn-site induces three different types of XRD patterns which depend largely on the Si content in the compound. For 0 ≤ x ≤ 0.5, XRD analysis reveals the presence of a pure tetragonal phase of solid solution with I-42m as a space group. Mixed tetragonal and orthorhombic phases were observed for 0.5 < x < 0.8, followed by a pure orthorhombic structure with a space group Pmn21 at high content of Si (x ≥ 0.8). 119Sn MAS NMR spectra show the presence of Sn/Si disorder as a function of the Si content. The 65Cu MAS NMR spectra of the quadratic solid solution confirm the presence of the two copper sites (Cu-2a and Cu-2c) at 780 ppm while in the case of the orthorhombic solid solution samples, a very broad band is observed. The optical properties were investigated of all compounds by UV-Vis diffuse reflectance and the obtained optical band gap values (1.31 to 2.43 eV) confirm a semiconductor character.

磁沉淀工艺在PCB印制线路板废水处理中的应用

广东某PCB印制线路板园区集中污水处理站设计水量为12000 m^(3)/d,总磷排放标准为0.5 mg/L,由于污水中含有部分次磷,深度处理采用芬顿氧化澄清工艺。该污水处理站地处工业园核心区,用地紧张,芬顿氧化配套的常规澄清池由于面积不足,存在漂泥情况,TP和SS难以稳定达标。根据现场情况,将现有的澄清池改造为磁沉淀高效澄清池,提高芬顿氧化出水净化指标。长期运行结果表明:磁沉淀工艺对PCB印制线路板废水芬顿氧化出水具有良好的澄清效果,在进水悬浮物浓度≤1000 mg/L,总磷≤2.0 mg/L时,出水悬浮物浓度≤30 mg/L,总磷≤0.5 mg/L,磁沉淀系统占地面积76 m^(2),沉淀表面负荷≥12.5 m^(3)/(m^(2)·h),处理水量峰值可达15000 m^(3)/d,运行电耗成本0.042元/t水,运行磁粉损耗成本为0.0113元/t水,自动化运行程度高,水质波动适应性强,出水稳定。

A Dynamical Approach to the Explanation of the Upper Critical Field Data of Compressed H3S

Excellent fits were obtained by Talantsev (MPLB 33, 1950195, 2019) to the temperature (T)-dependent upper critical field (Hc2(T)) data of H3S reported by Mozaffari et al. [Nature Communications 10, 2522 (2019)] by employing four alternative phenomenological models, each of which invoked two or more properties from its sample-specific set S1 = {Tc, gap, coherence length, penetration depth, jump in sp.ht.} and a single value of the effective mass (m*) of an electron. Based on the premise that the variation of Hc2(T) is due to the variation of the chemical potential μ(T), we report here fits to the same data by employing a T-, μ- and m*-dependent equation for Hc2(T) and three models of μ(T), viz. the linear, the parabolic and the concave-upward model. For temperatures up to which the data are available, each of these provides a good fit. However, for lower values of T, their predictions differ. Notably, the predicted values of Hc2(0) are much higher than in any of the models dealt with by Talantsev. In sum, we show here that the addressed data are explicable in a framework comprising the set S2 = {μ, m*, interaction parameter λm, Landau index NL}, which is altogether different from S1.

Analysis of Spectroscopic, Optical and Magnetic Behaviour of PVDF/PMMA Blend Embedded by Magnetite (Fe₃O₄) Nanoparticles

In the present work, magnetite (Fe3O4) nanoparticles have been prepared by a simple chemical method. Polymer nanocomposites based on the blend between poly vinylamine fluoride (PVDF) and (methyl methacrylate) (PMMA) doped with different concentrations of Fe3O4 nanoparticles have been prepared. The structural, optical, and magnetization properties of the nanocomposite samples were studied using suitable techniques. The X-ray study reflected that the cubic spinal structure of pure Fe3O4 crystal. No small peaks or ripples were found in the X-ray spectra, conforming to good dispersion of Fe3O4 within PVDF/PMMA matrices. The FT-IR analysis demonstrated the miscibility between the PVDF and PMMA blend with the interaction between the polymer blend and Fe3O4. The values of the band gap from UV-Vis study were decreased up to 4.21 eV, 3.01 eV for direct and indirect measurements, respectively. The magnetization was measured as a function of the applied magnetic field in the range of −2000 - 2000 Oersted. The curves of the magnetization indicated a paramagnetic behavior of pure Fe3O4 nanoparticles and PVDF/PMMA-Fe3O4 nanocomposites. The values of saturation magnetization for pure Fe3O4 are nearly 75 emu/g, exhibiting a paramagnetic behavior, and it is decreased with the increase of Fe3O4 content.

含UDE附加阻尼支路的构网型直驱永磁同步风电机组次同步振荡抑制策略

针对构网型直驱永磁同步风电机组在弱电网下的次同步振荡问题,该文提出了基于不确定性和扰动估计器(UDE)的附加阻尼支路振荡抑制策略。首先,网侧变流器采用虚拟同步机(VSG)技术,并基于谐波线性化理论建立了网侧变流器序阻抗模型;其次,深入分析引入电压电流双闭环控制对弱电网下构网型直驱永磁同步风电机组产生次同步振荡的影响特性,提出了电流环引入UDE附加阻尼支路的振荡抑制策略,并基于UDE的附加阻尼控制采用滤波带宽思想对系统扰动进行估计,通过动态电压补偿方式实现阻尼支撑,可有效抑制次同步振荡,提升系统鲁棒性;最后,通过时域仿真验证了所提振荡抑制方法的有效性。

一种抑制高速电机低次电流谐波的调制方法

针对高速永磁同步电机低载波比、数字控制延时所引起的电流谐波较大的问题,提出一种抑制低次电流谐波的改进型特定次谐波消除调制方法。首先,对该调制方法的调制波形原理和数字实现特点进行分析,建立新的电压谐波方程和开关角求解方程;其次,以电流总谐波失真为目标优化函数,研究了调制比和载波比对开关角分布、电流谐波含量的影响;最后,以三相高速永磁同步电机为研究对象,搭建系统仿真模型对所提调制方法进行验证。验证结果表明,通过与特定次谐波消除调制方式相比,所提调制方法计算量更少,可以提高输出脉宽调制波形的对称性,具有更优的低次电流谐波抑制能力。

模块化多电平换流阀子模块用真空旁路开关设计

模块化多电平换流阀(MMC)子模块的可靠性直接影响到柔性直流输电系统的整体稳定性,旁路开关是决定子模块关断性能的关键设备之一。文中基于永磁机构的工作原理和理论建立一种双线圈旁路开关模型,利用仿真分析电容储能电压、电容值、线圈线径和匝数以及弹簧参数对开关动态特性的影响规律,并对其动态特性进行优化设计。最后根据仿真结果制作样机并进行试验验证,测试结果表明:旁路开关满足在3 ms内合闸,零弹跳的技术要求,且通过雷电冲击试验、工频耐压试验、方波电压试验3项绝缘试验。

Sm2Fe17Nx永磁材料研制进展

简述了Ｓｍ２Ｆｅ（１７）Ｎｘ化合物的结构与内禀磁性能，着重回顾了Ｓｍ２Ｆｅ（１７）Ｎｘ永磁合金粉及其磁体的制备工艺发展现状，并展望了Ｓｍ２Ｆｅ（１７）Ｎｘ永磁体的发展前景。

三种探测技术在舟山港航道扩建工程海底管线探测中的联合应用

海底管线路由探测对航道疏浚施工具有重要意义,而传统的探测技术手段单一,效率较低,无法确定掩埋段信息。为提高海底管线探测结果精度及作业效率,依托宁波舟山港条帚门航道扩建工程项目,综合利用侧扫声呐、浅剖及海洋磁探对工程区域海底管线进行探测:利用侧扫声呐成果作为裸露段海底管线探测结果的基本支撑,浅剖埋深结果与磁探反演埋深结果相互印证,共同提高了海底管线判别的准确性。工程应用结果表明,三种探测技术手段在海底管线探测方面的联合应用成果可靠,探测精度和作业效率显著提升,且具有较好的适用性,在类似项目中具有较好的参考和推广作用。

风电柔直并网虚拟阻抗次同步振荡抑制策略

直驱风电场经柔性直流输电系统并网送出存在次同步振荡风险。首先,在建立直驱风电经柔直并网系统模型的基础上,采用失稳特征根模态分析方法,研究了V/F控制模式下系统次同步振荡模态的参与变量与参与因子。其次,以抑制系统次同步振荡为目标,提出了在柔直换流站电压外环控制器中配置高通滤波器等不同形式下的虚拟阻抗控制策略,且解析了阻抗参数的选择范围及其原则,并采用阻抗分析方法研究了阻抗控制器对系统阻抗特性的影响以及规律。最后,基于MATLAB电磁暂态仿真验证了所提次同步抑制策略的有效性及其参数解析计算的正确性。

基于ALFF/fALFF的肾虚证认知功能下降的神经机制研究

目的初步探究肾虚证亚健康人群认知功能改变的神经影像学机制。方法对35例肾虚型亚健康受试者和35例健康对照进行重复性成套神经心理状态测验(Repeatable Battery for the Assessment of Neuropsychological Status,RBANS)及评估,并进行静息态功能磁共振扫描。应用皮质分析方法计算两组被试脑区的低频震荡振幅(amplitude of low frequency fluctuations,ALFF)值和分数低频振幅(fractional ALFF,fALFF)值,并分析异常功能活动脑区与认知功能及临床症状之间的相关性。结果与健康受试者相比,肾虚型亚健康受试者的即刻记忆、注意编码及RBANS测验总分显著降低;并发现其左侧初级视觉皮质、左侧背侧枕叶皮质及右侧辅助运动皮质等脑区的ALFF/fALFF值异常改变。此外,左侧背侧枕叶皮质、右侧额叶眼动区ALFF值,左侧初级视觉皮质fALFF值与肾虚证积分均成正比。右侧额叶眼动区ALFF值,右侧辅助运动皮质fALFF值与测验总分成反比。结论肾虚型亚健康受试者的记忆与注意功能受损,左侧枕叶和右侧额叶等多个脑区神经活动的改变可能是肾虚证亚健康人群认知功能改变的潜在神经机制。

大容量直驱风机集群经柔直并网引起的次同步振荡概率评估

针对海上风电集群经多端柔直并网时的次同步振荡(SSO)频发问题,提出了一种基于Weibull分布模型和带漏项最小均方算法的SSO概率评估方法,分析了大容量直驱风机集群经柔直并网引起的SSO变化特性。仿真结果表明:风速增加使SSO频率由40 Hz下降至18 Hz附近,负阻尼比累计概率由14%增至90%;构成风电场的等值风机台数增加与多端柔直并网可以扩展SSO频率分布区间,并降低1%~8%的SSO负阻尼比累计概率。

Optimized analysis of sharpening characteristics of a compact RF pulse source based on a gyro-magnetic nonlinear transmission line for ultrawideband electromagnetic pulse application

We constructed a compact high-power RF pulse generator based on a gyro-magnetic nonlinear transmission line(GNLTL) to produce a high-voltage pulse with a sub-nanosecond rise time and a relatively high repetition rate, which shows great potential for application in the high-power ultrawideband electromagnetic effect, etc. The influence of incident pulse parameters(rise time and voltage amplitude) and line length on the sharpening characteristics of the GNLTL were investigated experimentally to optimize the rising rate of the modulated pulse front. Based on the GNLTL equivalent circuit model consisting of an LC ladder network, the rise time, the voltage conversion coefficient and the rising rate properties of a modulated pulse were also numerically analyzed in a wider range. The results show that a?>?90 k V RF pulse with a rise time of 350 ps and a repetition rate of 1 kHz in burst mode is produced by the GNLTL at an axial biasing magnetic field of 22 kA m^-1 and a line length of 30 cm under the condition of a 70 kV incident pulse. Applying a faster and higher incident pulse is conducive to improving the sharpening effect of the GNLTL. Furthermore, within a certain range, increasing the line length of the GNLTL not only reduces the rise time, but increases the voltage conversion coefficient and the rising rate of a modulated pulse. Furthermore, considering the energy loss of ferrite rings, there is an optimal line length to obtain the fastest rising rate of a modulated pulse front edge.

Cosmic Ether, Possessing Electric-Tension and Magnetic-Resistance, Is the Unified Field for Physics

The paper presents the case that physics is already and effectively unified by the energetic tension field, ether. We identify this integrating power of ether first, by re-defining the action generating parameters of this energetic tension field as the electric-tension, , and the magnetic-resistance, μ0, while re-deriving the Maxwell’s wave equation in analogy with the mechanically stretched string, where the . Then, replacing by and m0 by , one can find that almost all working physics theories are being energized byand μ0. To complete the unification, we can now postulate that the particles are also freely propagating EM waves, but they are spatially localized as in-phase, close-looped (IP-CL) vortex-like propagation modes of ether. Because of their IP-CL mode structure, they have space-finite spatial structures and remain spatially stationary in the absence of any spatially influencing potential gradients (forces) in their vicinity. Particles’ harmonic phase driven interactions between quantum particles give birth to the appearance of wave-particle duality. There is no need for the confusing and unnecessary de Broglie’s Pilot Wave. The inertia to spatial motion of IP-CL modes automatically accommodates Newton’s laws of motion. The cosmic universality of Maxwellian wave velocity, and particles as IP-CL modes, jointly accommodate the two key postulates of special relativity without the need for unphysical four-dimensionality. The observable universe is represented only by its diverse oscillatory excited states. The stable and stationary Cosmic Ether keeps holding 100% of its energy all the time. We have proposed a one-way light pulse propagation experiment to directly validate the existence of ether, rather than approaching Michelson’s way of measuring the ether drag. We have identified a good number of examples of working theoretical expressions in terms of and μ0 and presented our critical views in physics thinking, belonging to Classical, Relativity, Quantum and Cosmology Physics.

基于线圈子单元的永磁同步电机健康与定子绕组短路故障数学模型

针对相绕组为基本单元的永磁同步电机定子绕组短路故障数学模型,存在故障空间位置影响无法计及、不同短路故障需要重新建模,且无法研究健康状态时线圈对电机性能的贡献等问题,该文提出一种基于线圈子单元的永磁同步电机健康与定子绕组短路故障数学模型(APM)。首先,将每个线圈分割为多个线圈子单元,分别建立各子单元的电压、阻抗和空载反电动势等物理量的矩阵方程,利用基尔霍夫电压定律建立所有子单元的电压方程,建立电机的电磁功率和转矩方程。其次,利用有限元法和拟合法建立考虑槽内空间位置关系的线匝电感矩阵,通过矩阵变换得到计及位置信息的子单元电感矩阵。然后,在Matlab/Simulink中建立APM的仿真模型和图形化界面,通过修改抽头编号及图形化界面中短路电阻模块的连接位置,计算电机健康和不同类型定子绕组短路故障下的电磁特性。最后,有限元仿真和实验结果验证了模型的正确性和准确性,表明APM不仅可以精细地分析健康状态时线圈对电机性能的贡献,也可以高效、准确地分析线圈内部不同位置短路故障对电机性能的影响。该文研究可以为永磁同步电机的设计、故障诊断和容错控制提供依据。

Quantification of the Diminishing Earth’s Magnetic Dipole Intensity and Geomagnetic Activity as the Causal Source for Global Warming within the Oceans and Atmosphere

Quantitative analyses of actual measurements rather than modeling have shown that “global warming” has been heterogeneous over the surface of the planet and temporally non-linear. Residual regression analyses by Soares (2010) indicated increments of increased temperature precede increments of CO2 increase. The remarkably strong negative correlation (r = -0.99) between the earth’s magnetic dipole moment values and global CO2-temperature indicators over the last ~30 years is sufficient to be considered causal if contributing energies were within the same order of magnitude. Quantitative convergence between the energies lost by the diminishing averaged geomagnetic field strength and energies gained within the ocean-atmosphere interface satisfy the measured values for increased global temperature and CO2 release from sea water. The pivotal variable is the optimal temporal unit employed to estimate the total energies available for physical-chemical reactions. The positive drift in averaged amplitude of geomagnetic activity over the last 100 years augmented this process. Contributions from annual CO2 from volcanism and shifts in averaged geomagnetic activity, lagged years before the measured global temperature-CO2 values, are moderating variables for smaller amplitude perturbations. These results indicated that the increase in CO2 and global temperatures are primarily caused by major geophysical factors, particularly the diminishing total geomagnetic field strength and increased geomagnetic activity, but not by human activities. Strategies for adapting to climate change because of these powerful variables may differ from those that assume exclusive anthropomorphic causes.

Quantification of the Diminishing Earth’s Magnetic Dipole Intensity and Geomagnetic Activity as the Causal Source for Global Warming within the Oceans and Atmosphere

Quantitative analyses of actual measurements rather than modeling have shown that “global warming” has been heterogeneous over the surface of the planet and temporally non-linear. Residual regression analyses by Soares (2010) indicated increments of increased temperature precede increments of CO2 increase. The remarkably strong negative correlation (r = -0.99) between the earth’s magnetic dipole moment values and global CO2-temperature indicators over the last ~30 years is sufficient to be considered causal if contributing energies were within the same order of magnitude. Quantitative convergence between the energies lost by the diminishing averaged geomagnetic field strength and energies gained within the ocean-atmosphere interface satisfy the measured values for increased global temperature and CO2 release from sea water. The pivotal variable is the optimal temporal unit employed to estimate the total energies available for physical-chemical reactions. The positive drift in averaged amplitude of geomagnetic activity over the last 100 years augmented this process. Contributions from annual CO2 from volcanism and shifts in averaged geomagnetic activity, lagged years before the measured global temperature-CO2 values, are moderating variables for smaller amplitude perturbations. These results indicated that the increase in CO2 and global temperatures are primarily caused by major geophysical factors, particularly the diminishing total geomagnetic field strength and increased geomagnetic activity, but not by human activities. Strategies for adapting to climate change because of these powerful variables may differ from those that assume exclusive anthropomorphic causes.

圆柱形推拉式电磁铁的电磁力数值算法

电磁力是推拉式电磁铁非常重要的参数,但由于磁场的非线性变化,解析计算困难。针对这一问题,利用柱状坐标系下的磁矢量势理论求解圆柱形推拉式电磁铁的电磁力。将整个螺线管磁场划分为多个子域并明确边界条件得到可求数值解的子域磁矢量方程组,再通过MATLAB软件编程实现磁矢量势、电感和电磁力等电磁特性数据的计算。对比有限元中铁芯磁导率分别为恒定值10 000和电工软铁的B-H曲线两种情况,说明了该数值算法的计算准确度及误差变化趋势,并分析了误差形成的原因。随着电流的加大铁芯会发生磁饱和,当磁饱和问题不严重时,数值算法的计算结果具有高准确度;随着电流的增加,铁芯发生磁饱和后误差迅速增加。实验中给圆柱形推拉式电磁铁施加不同大小的励磁电流,得到的输出推力结果与理论分析相符。

基于重磁异常的北京副中心地质构造特征和地热控制作用研究

重磁勘探对于分析地热系统特征和成因十分重要。北京城市副中心当前地热开发程度较低,为给地热资源可持续利用提供依据,对近期完成的1:50000高精度区域重力测量资料,开展了场源边缘检测、2.5D剖面反演和三维反演计算。利用归一化Theta图垂向导数和一阶水平方向导数获得了精度更高的断裂位置,研究了断裂汇交特征;使用频率域Parker-Oldenburg方法反演获得了两条不同方向剖面的基岩起伏形态;使用信赖域反演算法获得了5 km以浅地层三维视密度异常特征。在此基础上结合1:100000航磁和钻孔资料分析,综合研究了副中心地质构造特征及其地热控制作用,得到结论如下:(1)研究区断裂构造以近NE向和NW向为主。NE向断裂延伸较远、梯度带宽,但被NW向断裂切割改造迹象明显。(2)太古界结晶基底差异性隆升使区内储层和盖层厚度变化大。研究区南部隆起区蓟县系储层厚度变薄或缺失。新生界盖层在隆起区厚度为200~800 m,在断陷盆地区达2000 m以上。(3)南苑—通县断裂和夏垫断裂是区内良好导热构造;NW向台湖断裂、张家湾断裂与NE向燕郊断裂、姚辛庄断裂是主要导水通道,与南苑—通县断裂和夏垫断裂交汇形成区内地热资源的主要补给径流通道。区内地热异常受不同级次构造控制在赋存特征上呈现较大差异。

煤矿电磁兼容标准体系构建

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