Preparation,microstructure and ion-irradiation damage behavior of Al4SiC4-added SiC ceramics

Single-phase Al₄SiC₄ powder with a low neutron absorption cross section was synthesized and mixed with SiC powder to fabricate highly densified SiC ceramics by hot pressing. The densification of SiC ceramics was greatly improved by the decomposition of Al₄SiC₄ and the formation of aluminosilicate liquid phase during the sintering process. The resulting SiC ceramics were composed of fine equiaxed grains with an average grain size of 2.0 μm and exhibited excellent mechanical properties in terms of a high flexure strength of 593 ± 55 MPa and a fracture toughness of 6.9 ± 0.2 MPa m^1/2. Furthermore, the ion-irradiation damage in SiC ceramics was investigated by irradiating with 1.2 MeV Si⁵⁺ ions at 650 °C using a fluence of 1.1 × 10¹⁶ ions/cm², which corresponds to 6.3 displacements per atom (dpa). The evolution of the microstructure was investigated by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The breaking of Si–C bonds and the segregation of C elements on the irradiated surface was revealed by XPS, whereas the formation of Si–Si and C–C homonuclear bonds within the Si–C network of SiC grains was detected by Raman spectroscopy.     

惠州水文监测综合管理平台设计与实现

针对目前部分水文要素监测工作中还存在大量人工记载、计算、录入，成果出错率较高，时效性低， 监测业务融合度不够和内部管理难度大等方面的问题，深度融合互联网技术和水文监测业务，开展“互联网 + 水文监测”研究，设计并开发分局水文监测综合管理平台是十分必要的。深入分析水文监测各项业务流程，打造水文监测在线业务流、数据流和管理流，结合程序开发语言和互联网技术，完成惠州水文监测综合管理平台设计。平台在 2020 年 6 月东江流域洪水中进行实际应用，结果表明：平台实现水文监测要素人工作业无纸化、 自动化、智能化，进一步提高水文监测工作效率和信息化水平，具有很好的推广应用前景。     

Synthesis of pure nanocrystalline ZrO2 via a simple sonochemical-assisted route

Pure nanocrystalline zirconia was synthesized via a sonochemical-assisted method based on the reaction between zirconyl nitrate and propylenediamine. Here, propylenediamine for the first time was used as precipitating agent to fabricate nanocrystalline zirconia via a sonochemical-assisted method. The effect of solvent and concentration of propylenediamine on the morphology and crystallite size was investigated. It was shown that morphology and crystallite size of the as-synthesized products could be greatly affected by these parameters. The as-prepared products were characterized by SEM and TEM images, XRD patterns, FT-IR and EDS spectroscopy.     

Role of molecular oxygen on the synthesis of Ni(OH)2/TiO2 photocatalysts and its effect on solar hydrogen production activity

Molecular oxygen performs a vital role in the photocatalytic activity of anatase TiO₂, but there is a little experimental insight into the role of molecular oxygen on the synthesis of TiO₂ based photocatalysts. Herein, we have shown that Ni(OH)₂/TiO₂ prepared in the presence and absence of molecular oxygen results in significantly varied hydrogen production activity. The sample synthesized in the presence of O₂ and N₂ produced 6624 μmol/h/g and 4468 μmol/h/g of hydrogen under direct solar light exposure. Additionally, the samples prepared in the presence of light irradiation produced 8289 μmol/h/g of hydrogen, a 72 fold jump in hydrogen production compared to TiO₂. XPS, FTIR, Raman, and ESR measurements were carried out to investigate the underlined mechanism for such variation in the photocatalytic activity. Our results suggest that the presence of molecular oxygen during Ni(OH)₂/TiO₂ synthesis causes the formation of terminal OH and reduced the oxygen vacancies on the surface of TiO₂, which can significantly alter the H₂ production. Also, the reusability of the photocatalysts is greatly affected by the synthesis conditions, namely the presence of light and molecular oxygen.     

Synthesis and photoluminescent properties of orange-emitting Sm3+-activated KPb4(PO4)3 phosphor for LEDs

A series of Sm³⁺-doped KPb₄(PO₄)₃ phosphors have been successfully synthesized by high-temperature solid-state reaction method, and the structure, morphology and luminescent properties were investigated. The SEM images suggest that the prepared phosphor has an irregular morphology with a diameter of about 10 ~ 20 μm. Under near-ultraviolet (NUV) light (404 nm) excitation, all prepared phosphors KPb_4-xSm_xP₃O₁₂ (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1, 0.15, 0.2, 0.3, 0.4 and 0.5) show the characteristic f → f emission bands of the Sm³⁺ activator. And the emission intensities have an upward trend with increasing the Sm³⁺ concentration when x is lower than 0.1. By monitoring 598 nm emission, the excitation spectrum of KPb_3.9Sm_0.1(PO₄)₃ contains a series of sharp bands in the range of 250 ~ 500 nm, which matches well with the NUV LED chip. The CIE coordinates of KPb_3.9Sm_0.1(PO₄)₃ phosphor was evaluated to be (0.5714, 0.4253), corresponding to orange color with a high color purity of about 90%.     

In situ electrodeposition of nickel cobalt selenides on FTO as an efficient counter electrode for dye-sensitized solar cells

Construction of transition metal selenides with high electrocatalytic performance is of significant importance, but it is still a challenge to develop the corresponding counter electrodes (CEs) by an electrodeposition technique. In the present work, nickel cobalt selenide (Ni_xCo_ySe) films are prepared in situ on fluorine-doped tin oxide (FTO) glasses through a potential reversal electrodeposition technique. The morphology and electronic structure of Ni_xCo_ySe films can be tuned by controlling the Ni/Co molar ratio in electroplating solution. Specially, Ni_xCo_ySe-6 film (the Ni/Co molar ratio of 1:1) with the optimized interaction between the Ni and Co elements displays numerous particles composed of sheets attached with nanocrystals, resulting in the more electrocatalytic active sites. Benefiting from the unique morphology and optimized synergistic effect, Ni_xCo_ySe-6 CE exhibits superior electrocatalytic activity for the triiodide reduction. Then, the dye-sensitized solar cell (DSC) fabricated by Ni_xCo_ySe-6 CE has demonstrated a power conversion efficiency (PCE) over 7.40%, which is higher than that of platinum (Pt)-based device (6.32%). Furthermore, Ni_xCo_ySe-6 array CE is also prepared by using polystyrene array as template. The PCE of the DSC with Ni_xCo_ySe-6 array CE reaches its maximum value of 7.64% and 20.9% larger than that of Pt-based device.     

甲子河拦河坝坝型选型设计

为了合理选择甲子河治理工程中拦河坝坝型,从功能要求、耐久性、运行管理与维护和景观等方面对3种设计方案进行了比选分析,最终选择底轴驱动翻板闸为拦河坝坝型,对有效推进甲子河的科学治理提供了有力的支撑和保障。     

混凝土路面道路工程鉴定检测技术

探讨了混凝土路面道路工程鉴定检测内容和方法,为工程验收提供依据。     

管网压力控制模型与DMA分区减漏探讨

介绍了管网压力控制模型的功能及建立过程,并将其应用于桂城水厂。运行结果表明,采用管网压力控制模型后,桂城水厂平均出厂压力为0.483 4 MPa,千吨水电耗及漏损率分别降低6.28%和3.14%;用管网压力控制模型修正的压力代替宏观模型优化后的压力,有利于在供水调度过程中实现节能节水;管网压力控制模型与DMA分区阀门减漏联合作用,可以有效降低管网的漏损率;基于管网压力控制模型建立压力流量预测控制系统,使泵群按照管网压力曲线运行,可以降低电耗并减少漏损。     

基于变论域模糊PID控制的同步发电机励磁研究

将变论域自适应模糊PID控制器应用于同步发电机的励磁调节与控制中.论述了控制器的结构设计、伸缩因子的选择方法,给出了具体的控制算法.通过采集机端电压以及电压的偏差作为控制器输入,然后通过模糊处理,对比例、积分、微分系数进行实时调整,由于传统的模糊PID励磁控制器对这3个参数调节精度不高,借鉴变论域思想,通过选择合适的伸...