C,N co-doped Co3O4 hollow spheres prepared via hydrothermal reaction for improved electrochemical activity

Superior electrode materials play a key role on the electrochemical performance for the lithium-ion batteries and supercapacitors. The Co₃O₄-based materials are promising electrode materials due to their high specific capacity and energy density. However, the poor cycle performance limits their applications during the process of the commercialization for the lithium-ion batteries and supercapacitors. Because of the poor cycle stability, C, N co-doped Co₃O₄ hollow spheres are successfully prepared and used as electrode materials for the lithium-ion batteries and supercapacitors. Via the C, N co-doping process, the electronic conductivity is greatly improved. Moreover, the hollow structure could ensure the structural stability during the electrochemical process. As a result, the cycle performance and specific capacity are greatly improved when the C, N co-doped Co₃O₄ composites are used as electrode materials for the lithium-ion batteries and supercapacitors.     

Reactions of alcohols with hydrogen sulfide over zeolites: IV. The role of acidity in the hydrosulfurization of ethanol over X-type zeolite catalysts

The reaction of ethanol with hydrogen sulfide was studied on divalent cation-exchanged X-type zeolites at 523 K. The decomposition of ethanol to hydrocarbons is competitive with the hydrosulfurization process, i.e., the reaction between EtOH and H₂S. Brönsted acid sites together with divalent cations are involved in the hydrosulfurization of ethanol. Cation sites take part in the formation of ethanethiol. The increase of the strength of Brönsted acid sites causes the increase of the selectivity towards diethyl sulfide.     

基于HI-DD-AdaBoost.RT的锂离子动力电池SOH预测

锂离子电池是一个复杂的电化学动态系统,实时准确的健康状态(SOH)估计对电动汽车动力锂电池的维护至关重要,传统建模方法难以实现SOH的在线估算.基于此,从实时评估电池的SOH出发,在增量学习的基础上,选取与电池健康状态相关的指标建立SOH预测模型.考虑到增量学习中的耗时性问题,提出融合滑动窗口技术的HI-DD算法,该算法可以检测概念漂移是否发生,从而指导和确定模型更新位置;设计出HI-DD与AdaBoost.RT结合的模型更新策略,进而提高模型的在线学习性能和预测精度,最后使用CALCE提供的电池老化实验数据对所提出的方法进行验证.结果表明,基于增量学习的HI-DD-AdaBoost.RT预测算法具有较强的在线更新能力和较高的预测精度,能够满足SOH在线预测的实际需求.     

Effect of zinc oxide addition in slag system and heating manner on boron removal from metallurgical grade silicon

Different amount of ZnO was added to calcium silicate reagent to improve boron removal from metallurgical grade silicon (MG-Si). The thermodynamic analysis showed that the reagent CaO-SiO₂-ZnO had a stronger ability to boron removal than the reagent CaO-SiO₂. Two kinds of heating manners of electromagnetic induction and resistance were used to refine MG-Si. Compared with the resistance heating, the induction heating showed a much higher efficiency of boron removal. The mechanism of boron removal from MG-Si by ternary CaO-SiO₂-ZnO slag reagent was put forward and the role of ZnO in slag to boron removal was described. The by-product Zn in refined silicon can be thoroughly removed by a vacuum distillation treatment, which showed an absolute advantage to the residual zinc removal in silicon by comparison with the acid leaching treatment. The residual zinc in silicon was reduced to lower than 0.05 ppmw after a vacuum treatment at 1723 K.     

Angular velocity calibration system with a self-calibratable rotary encoder

Gyroscopes are essential components of electronic stability control systems (ESC), which are currently incorporated in automobiles to reduce car accidents. To meet the traceability requirements of gyroscopes in ESC testing system, a novel type of angular velocity calibration system was developed at the National Metrology Institute of Japan. The system is equipped with a self-calibratable rotary encoder (SelfA), operating on the same self-calibration principle as the national angle standard in Japan. To evaluate the performance of the system, the stability of the measured angular velocity was examined in both time domain and in terms of Allan variance. The noise effect from the slip ring was also measured. The calibration procedure was demonstrated by monitoring the response of a fiber-optic gyroscope from −180°/s to 180°/s at 30°/s intervals. The results confirmed that the system performance satisfies the requirements for angular velocity calibration of mid-performance MEMS gyroscopes.     

Multi-scale intrinsic deformation mechanisms of 3D graphene foam

The mechanical properties and multi-scale deformation mechanisms of a freestanding 3D graphene foam are evaluated for the first time. Nanoindentation is used to evaluate the nanoscale properties in compression whereas in situ tensile testing inside scanning electron microscope (SEM) is used to evaluate the tensile properties of the bulk foam. Nano-compression results show that the hardness (19.9–26.1 kPa) and elastic modulus (1.2–1.5 MPa) of the foam are relatively low. The deformation mechanisms in compression are graphene branch bending and branch wall elastic depression, which do not utilize the exceptionally high in-plane mechanical properties of graphene. The elastic modulus (69.9 GPa) during tensile loading is found to be four orders of magnitude higher owing to graphene branch alignment which enables branches to bear load along the high strength in-plane direction of graphene. In situ SEM tensile testing of free standing 3D graphene foam supports the proposed mechanisms and reveals that the ductile graphene branches gradually become aligned by rotating at rates of ∼0.59 °/s, while the brittle node junctions become aligned abruptly at rates of ∼3.08 °/s. It is observed that due to defects such as cracked branches and discontinuous graphene sheets, only a fraction of graphene branches bear significant loads.     

Mechanical properties of sintered Ag–Cu die-attach nanopaste for application on SiC device

In this work, mechanical properties of Ag–Cu nanopaste that formulated by mixing Ag and Cu nanoparticles with organic compounds have been reported. Various weight percents of Cu nanoparticles (20–80 wt%) had been loaded in the nanopaste, in which an increasing trend for hardness, stiffness and Young’s modulus were recorded with the increment of Cu loading. When the nanopaste was used to bond two pieces of Cu substrates, a declining of bonding strength has been recorded with an increasing of Cu loading. For metallization studies, Ag and Au coatings on Cu substrate have displayed the highest (52.6 MPa) and the lowest (34.4 MPa) bonding strength, respectively. The values of bonding strength were found to have a close relationship with the interface microstructure between the nanopaste and metallization layer on the substrate. Finally, the nanopaste was used to attach a SiC die on a substrate with either Ag or Au coating. The entire bonding structure has undergone a thermal aging test, whereby the thermal-aged microstructure was in agreement with the microstructure of metallization studies.     

Surfactant-assisted hydrothermal synthesis of Fluoridated Hydroxyapatite nanorods

Fluoridated Hydroxyapatite (FHA) nanorods were synthesized using Apricot Tree Gum (ATG) as a novel surfactant and then compared with Ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA) and Sodium Dodecyl Sulfate (SDS) as conventional surfactant agents under hydrothermal condition (70 °C and 1 atm). The effects of pH values and various types of surfactants on the formation of the FHA nanorods, crystalline phase, and chemical compositions were investigated using Field Emission Scanning Electron Microscopy (FESEM) equipped by Energy Dispersive X-ray (EDX), X-Ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). The findings indicated application of the presented ATG as surfactant is able to produce the hexagonal nanorods of FHA along their c-axis direction. Moreover, it is illustrated that diameter and length of nanorods which is obtained by ATG surfactant are bigger than EDTA and SDS. In addition, it is demonstrated that pH values can play a major role on formation of hexagonal FHA nanorods. The increase of pH transformed the shape of synthesized FHA from particles to rods. Ultimately, based on the similarity of synthesized FHA nanorods to the shape, structure, and composition of enamel; it is suggested for its potential to be used for dental applications.     

Robust adaptive cross-coupling position control of biaxial motion system

The stability and synchronous performance are usually hard to be improved simultaneously in the biaxial cross-coupling position motion control system.Based on analyzing the characteristics of the cross-coupling control system,a robust adaptive cross-coupling control strategy is proposed.To restrict influences of destabilizing factors and improve both of stability and synchronous performance,the strategy forces dual axes to track the same reference model using Narendra adaptive control theory.And then,a robust parameters adaptive law is proposed.The stability analysis of the proposed strategy is conducted by applying Lyapunov stability theory.Related simulations and experiments indicate that the proposed strategy can improve synchronous performance and stability simultaneously.     

基于三维光学信息的人体姿态快速测量

汽车中人体姿态三维测量对汽车座椅设计的舒适性评价具有重要的意义。为了快速准确地获取车内人体三维数据,文中采用一种基于双目视觉的立体三维数据获取方法,该方法将结构光与标记点相结合,实现了人体三维点云快速重建以及三维姿态(距离、角度)自动快速测量。实验结果表明,该方法在距离2 m以上,测量范围1.5 m×2 m时,人体姿态测量精度可以达到0.03 mm,满足了汽车人体姿态高精度三维数据采集的需求。与传统的汽车人体姿态三维测量方法相比,文中所使用的三维自动测量方法不仅自动化程度高,而且具有测量精度高、速度快、鲁棒性强的优点。