Hierarchical architecture of Bi12TiO20 via ethylene glycol-mediated synthesis route

Hierarchical architecture of cubic sillenite bismuth titanate (Bi₁₂TiO₂₀) is successfully synthesized using simple ethylene glycol-mediated self-assembly; followed by calcination under air at 600 °C for 30 min. The products are characterized using field emission scanning electron microscopy (FE-SEM), fourier transform infrared spectroscopy (FT-IR), thermogravimetric-differential thermal analysis (TG-DTA), and X-ray diffraction (XRD). The reaction time has an effect on the product morphology, which changed from a leaf- and circular plate-like structure to a completely formed hierarchical structure within 2 h. The hierarchical structure of Bi₁₂TiO₂₀, having a size around 3 μm, is composed of 2D twist nanoplates, and each twist nanoplate has a thickness around 10–30 nm.     

电气设备常见故障及其分析方法

分析电器设备常见故障,找出原因并解决;结合自己平时日常工作实践进行分析;通过总结得出了电气设备的常见故障并提出了分析方法;电气设备常见故障通常是由变电设备故障控制设备和控制电路引起,分析故障原因从状态、图形、单元、回路、计算机等几个方面出发,确定故障的部位后维修。     

Effect of Glass Additions on the Indentation-Strength Behavior of Alumina

The effect of small calcium aluminosilicate (CAS) glass additions on the microstructure and flaw tolerance of alumina ceramics is investigated, and the results compared to a high-purity alumina. The high-purity alumina specimens were dense with microstructures consisting of a uniform grain size distribution and equiaxed grain morphology. Additions of only 1 wt% glass phase resulted in a bimodal grain size distribution containing large, elongated grains within a fine-grain matrix. Indentation-strength tests indicated enhanced flaw tolerance with the bimodal microstructure, even though both materials had nominally the same average grain size. The strength of unindented specimens was also observed to decrease with glass additions. Observations of crack paths show a greater propensity for bridging in the glass-containing alumina due to the presence of coarse, elongated grains and perhaps a lower grain boundary toughness. However, crack extension occurs transgranularly when the size of the coarsest grains becomes too large. This suggests that an optimum in flaw tolerance will be achieved with an elongated grain morphology and intermediate grain size.     

真空断路器手车自动控制器的设计

针对国家电网对真空断路器手车需自动控制的要求,采用MC68HC908GR8单片机实现主控与通信功能,双继电器实现电机控制,霍尔电流互感器实现对电机电流的采样,设计了一种具有对手车自动投切、电机正反转控制、电机堵转保护、远程状态显示等特点的智能控制器。通过各种配柜功能测试、电磁兼容试验及现场投入运行,结果表明该控制器能精确测量,投切稳定、可靠。     

Nanoarchitecture of variable sized graphene nanosheets incorporated into three-dimensional graphene network for dye sensitized solar cells

A novel three-dimensional (3D) nanoarchitecture consisting of hybrid graphene nanosheets (GNs)/graphene foam (GF) was fabricated on the FTO conducting substrate as a high efficient counter electrode (CE) for dye sensitized solar cells (DSSCs). The GNs with various sized such as large-sized heat-reduced graphene nanosheets (H-GNs) and small-sized laser-reduced graphene quantum dots (L-GQDs) were synthesized and used as catalytic materials incorporated into a 3D GF network, respectively. In this design, the aggregations and restacking of GNs were efficiently reduced, which is beneficial for increasing the amount of the active defective sites at the edges of graphene to the electrolyte solution. Especially, L-GQDs with smaller dimension less than 100 nm have more active defective sites at edges, providing superiority over the large-sized H-GNs in terms of electrocatalytic activity. Meanwhile, the GF network with high conductivity provides fast electron transport channels for charge injection between the GNs and FTO. The DSSC with this hybrid CE exhibited energy conversion efficiency (η) of 7.70% with an open circuit voltage (V_OC), short circuit photocurrent density (J_SC) and fill factor (FF) of 760 mV, 15.21 mA cm⁻², and 72.0%, respectively, which is comparable to that of the conventional Pt CE (7.68%).     

低浓纸浆臭氧漂白经验模型的建立

以臭氧(O_3)用量作为自变量,纸浆卡伯值(K)、黏度和白度为响应值,研究了臭氧用量对纸浆漂白性能的影响,结果表明,臭氧最佳用量为0. 77%,此时漂白后纸浆卡伯值、黏度、白度分别为8. 1、658. 4 mL/g、41. 9%。计算漂白过程中脱木素选择性、单位臭氧消耗内卡伯值的降低率和白度的增加率,通过线性回归建立合适的数学模型,求出各因素随臭氧用量(O_(3CON))或卡伯值的预估函数。研究表明,硫酸盐阔叶木浆低浓臭氧漂白时,臭氧用量对卡伯值的关系采用指数模型较为合适,其方程为K=7.359(O_(3CON))~(-0.2318), R~2=0.9987。结合黏度、白度随卡伯值变化的方程,臭氧用量取0. 77%、其他条件一定时,通过该模型预测得到纸浆卡伯值、黏度、白度分别为7. 8、624. 2mL/g、42. 9%,该经验模型可预测并优化低浓硫酸盐阔叶木浆的臭氧漂白反应。     

梯度电容调控的无功功率补偿控制器设计

提出了一种梯度电容调控的无功功率补偿控制器设计方法。采用不等容分组方法,提高投切电容的容量精确性,降低调控时间。利用ATmega2560芯片,实现对系统功率因数和电流电压的测量、投切电容的控制等功能。设计了系统的硬件电路,并通过软件进行模拟仿真。仿真结果表明,在负荷变化和有谐波影响的情况下,采用梯度电容调控的无功功率补偿控制器可以迅速将功率因数补偿至0.98以上。