基于电信号特征分析的电机故障诊断技术

介绍了电机故障诊断技术平台的组成,分析了电机常见故障下电信号的特征。利用宜昌和景洪工厂两台电机进行了实际对比测试,宜昌工厂电机定子电流特征频率在49.2Hz时表现出峰值-36.08dB,在50.8Hz时表现峰值则为-37.23dB,表明电机存在转子断条故障;景洪工厂电机在转子特征频率为113.51Hz时,出现峰值-58.47dB,表明电机存在静态偏心故障。经电机现场抽芯检查,验证了电机故障快速诊断平台给出的电机健康状态评估结果,证实了基于电信号特征分析的电机故障诊断技术的准确性。     

Isostructural phase transition (IPT) in CaMoO4 with Scheelite structure

The ceramic compound CaMoO₄ is synthesized via a solid-state reaction technique. Rietveld refinement studies were done on the powder X-ray diffraction data of CaMoO₄ and revealed that the compound is crystallized in the tetragonal Scheelite structure with I4₁/a space group. The differential scanning calorimetry (DSC) studies on CaMoO₄ divulged an anomaly around 440 °C. This anomaly is further probed using the temperature-dependent Raman and dielectric spectroscopic measurements and are corroborating with the results obtained from DSC. A detailed investigation on the temperature-dependent Raman spectroscopic data revealed that the A_1g mode of CaMoO₄ showed a soft phonon behavior up to the phase transition temperature. It is observed that the A_1g mode displayed phonon hardening behavior with further increasing the temperature. The anomaly is attributed to an isostructural phase transition (IPT), a rarely observed phenomenon in the compounds with Scheelite structure. The IPT in CaMoO₄ is elucidated with a phonon softening mechanism.     

基于Massive MIMO及频谱叠加的5G SA网络上行优化方法

大规模多输入多输出(Multiple-Input Multiple-Output, MIMO)可以有效提升5G SA网络的上行链路数据传输速率以及可靠性。针对5G SA网络上行链路速率和覆盖不均衡的情况,提出了基于大规模MIMO的分组算法,将发送信号矢量进行分组,组内采用最大似然检测,组外采用基于正交三角分解(QR分解)的干扰消除检测,并且结合5G频谱的叠加策略,在降低算法复杂度的同时,有效提升网络覆盖和速率。通过5G SA现网实测,通过MIMO降低分组数量能够提升分组检测性能,结合上行低频段频谱叠加策略能够有效提升5G SA网络上行覆盖30%,提升5G SA网络上行平均速率40%~80%,特别是弱覆盖边缘的网络速率,最高可达600%。     

Synthesis of Diamond@SiO2@Ag composite materials for high SERS effect

Among various carbon materials, diamond stands out due to excellent physical and chemical properties. In this work, we designed Dia@SiO₂@Ag composites combining diamond micropowder and Ag nanoparticles by a simple chemical method and obtained stable substrate for surface enhanced Raman scattering (SERS) owing to its high surface-to-volume ratio, low density, as well as close bond between diamond and Ag. As-prepared Dia@SiO₂@Ag presented high activity to detect crystal violet and rhodamine 6G molecules, which was demonstrated by significantly enhanced SERS spectra and high enhancement factor values (10⁸-10⁹). Moreover, Dia@SiO₂@Ag also showed desired sensitivity, which was investigated by detection limit. Therefore, our study provided more theoretical support and broadened the functional applications of diamond, particularly in Raman detection.     

Chloroquine-Induced Accumulation of Autophagosomes and Lipids in the Endothelium

Chloroquine (CQ) is an antimalarial drug known to inhibit autophagy flux by impairing autophagosome–lysosome fusion. We hypothesized that autophagy flux altered by CQ has a considerable influence on the lipid composition of endothelial cells. Thus, we investigated endothelial responses induced by CQ on human microvascular endothelial cells (HMEC-1). HMEC-1 cells after CQ exposure were measured using a combined methodology based on label-free Raman and fluorescence imaging. Raman spectroscopy was applied to characterize subtle chemical changes in lipid contents and their distribution in the cells, while the fluorescence staining (LipidTox, LysoTracker and LC3) was used as a reference method. The results showed that CQ was not toxic to endothelial cells and did not result in the endothelial inflammation at concentrations of 1–30 µM. Notwithstanding, it yielded an increased intensity of LipidTox, LysoTracker, and LC3 staining, suggesting changes in the content of neutral lipids, lysosomotropism, and autophagy inhibition, respectively. The CQ-induced endothelial response was associated with lipid accumulation and was characterized by Raman spectroscopy. CQ-induced autophagosome accumulation in the endothelium is featured by a pronounced alteration in the lipid profile, but not in the endothelial inflammation. Raman-based assessment of CQ-induced biochemical changes offers a better understanding of the autophagy mechanism in the endothelial cells.     

Polymorphism in Gd2Ge2O7 ceramics: Structural,vibrational, and optical features

In this work, Gd₂Ge₂O₇ polymorphs were obtained by solid-state reactions at 1100–1300 °C. Structural and vibrational features were investigated by X-ray diffraction and Raman spectroscopy. For the triclinic (space group P1) polymorph, all the predicted phonons were discerned in perfect agreement with the group theory calculations, while for the tetragonal polymorph (space group P4₁2₁2), 53 bands of the 81 predicted modes could be identified and characterized. The Gd³⁺ 4f-4f electronic transitions were investigated by diffuse reflectance spectroscopy in the range 200–340 nm. By applying the Kubelka-Munk function, it was possible to determine the bandgap values for all ceramics studied. The tetragonal polymorph exhibited higher bandgap values (5.88 eV) than the triclinic one (5.59 eV), which are both more energetic than other pyrochlore polymorphs reported in the literature. The results indicate that the presence of polymorphism in Gd₂Ge₂O₇ ceramics can be used to produce tailor-made materials since their crystal structures have a strong influence on their optical properties. Consequently, these properties could be used to tuning the optical properties of Gd-containing materials to sensitize and transfer energy to other luminescent lanthanide ions, aiming for innovative applications.     

激光在线测厚振动分析与精度优化

激光测厚具有安全可靠、测量精度高、测量范围大等优点,广泛应用于纸张、电池极片等薄膜类材料厚度的在线测量。带材宽幅方向扫描测厚时由于扫描架往复运动会产生机械振动,影响在线测厚精度。针对该问题,以锂离子电池极片厚度测量为例,使用双激光差动式测厚平台对电池极片和铜箔分别进行厚度测量,然后对测厚数据进行频谱分析,探究其振动规律的相似性,并基于频谱分析结果采用滑动带阻滤波方式对测厚数据进行处理,滤波后极片和铜箔的厚度极差分别降低了33.4%和73.8%,有效过滤了机械振动导致的测量误差,可满足极片和铜箔厚度测量的精度要求。     

Saliency4ASD: Challenge,dataset and tools for visual attention modeling for autism spectrum disorder

The recent studies showing that gaze features can be useful in the identification of Autism Spectrum Disorder (ASD), have opened a new domain where Visual Attention (VA) modeling could be of great help. In this sense, this paper presents a report of the Grand Challenge “Saliency4ASD: Visual attention modeling for Autism Spectrum Disorder”, organized at IEEE ICME’19, aiming at supporting the research on VA modeling towards this healthcare societal challenge. In particular, this paper describes the workflow, obtained results, and datasets and tools that were used within this activity, in order to help on the development and evaluation of two types of VA models: (1) to predict saliency maps that fit gaze behavior of people with ASD, and (2) to identify individuals with ASD from typical development.     

Fabrication and characterization of hot-pressed B-rich boron carbide

Boron carbide has a wide solubility range owing to the substitution of B and C atoms in the crystal. In this study, boron carbides with different stoichiometric ratios were prepared using a hot-pressing sintering method, and the influences of the B/C atomic ratio on the microstructures and properties were explored in detail. X-ray diffraction analysis showed that excessive B atoms caused lattice expansion. Raman spectroscopy analysis showed disordered substitution of B atoms in the chains and icosahedra. Analysis of the densification process and microstructure evolution revealed that the addition of B promoted densification, and more stacking faults and twins occurred in B-rich boron carbide, and result in the densification mechanism gradually changes from atomic diffusion mechanism driven by thermal energy to plastic deformation mechanism dominated by the proliferation of dislocation and substructures. The introduction of chemical composition changes by dissolving excessive B into boron carbide further affected the microstructure and consequently the mechanical properties. The Vickers hardness, modulus, and sound velocity all decreased with the increase in B content. Moreover, the fracture toughness improved with increased B content. The flexural strength of the samples was optimised at the B/C stoichiometric ratio of 6.1.     

Effect of Mn2+ doping on the lattice and the microwave dielectric properties of MgTa2O6 ceramics

A series of Mn²⁺-doped Mg_1-xMn_xTa₂O₆ (x = 0.02, 0.04, 0.06, 0.08, 0.10, 0.12) ceramics were synthesized by solid-state reaction method. The influence of introducing Mn–O bonds as a partial replacement for Mg–O bonds on the lattice and microwave dielectric properties was systematically investigated. XRD and Rietveld refinement confirm that Mn²⁺ occupies the 2a Wyckoff position and forms a pure trirutile phase. Moreover, based on the chemical bond theory, the dielectric constant is mainly affected by the ionicity of the Ta–O bond. The lattice and dielectric properties remain relatively stable with Mn²⁺ doping below 0.1, but excessive Mn²⁺ doping leads to pronounced distortion of the lattice, which is not beneficial for lattice stability and microwave dielectric properties. Introducing an appropriate amount of Mn–O bonds with high bond dissociation energy facilitates MgO6 octahedron stability, which improves the thermal stability of the lattice. Accordingly, the microwave dielectric properties for 0.06 Mn²⁺-doped MgTa₂O₆ ceramics were determined: ε_r = 28, Q × f = 105,000 GHz (at 7.5 GHz), τ_f = 19.5 ppm/^°C.