Structure,dielectric properties of novel Ba(Zr,Ti)O3 based ceramics for energy storage application

(1-x) Ba(Zr_0.2Ti_0.8)O₃-x Na_0.5Bi_0.5TiO₃ (x = 0, 10, 20 30, 40, 50 mol%) (BZTN) ceramics are prepared by the traditional solid phase method. All BZTN ceramics exhibit a pseudo-cubic BZT based perovskite structure. Both the average grain size and the relaxor ferroelectricity of BZTN ceramics gradually increase with increasing NBT content. The W_rec of 3.22 J/cm³ and η of 91.2% is obtained for the BZTN40 ceramic at 241 kV/cm. BZTN40 ceramic also exhibits good temperature stability from room temperature to 150 °C and frequency stability from 1 Hz to 100 Hz. A P_D of 0.621 J/cm³ and a t_0.9 of 82 ns is obtained for the BZTN40 ceramic at 120 kV/cm. BZTN ceramics show application potential in energy storage and pulse power capacitors.     

荧光磁性表面分子印迹聚合物对柚皮苷的荧光偏振检测

采用荧光磁性表面分子印迹法对柚皮苷进行荧光偏振检测。该方法以二氧化硅包裹的磁性颗粒为基质,甲基丙烯酸和丙烯酰胺为单体,并用异硫氰酸荧光素标记,得到同时具有荧光和磁性的表面分子印迹聚合物。并采用荧光偏振法和紫外分光光度法对制备的聚合物结合能力进行检测。通过与比较2种检测方法可知荧光偏振法更为灵敏,检出限为0.1?mg/L。最后对番茄酱中含有的柚皮苷进行回收率检测,回收率达到81.3%以上。说明采用荧光磁性表面分子印迹法对食品中柚皮苷可快速、高效地检测。     

Extreme high energy storage efficiency in perovskite structured (1-x)(Ba0.8Sr0.2)TiO3-xBi(Zn2/3Nb1/3)O3 (0.04 ≤ x ≤ 0.16) ceramics

Dielectric materials with high power density, fast charge and discharge rates, and high energy-storage density are urgently required due to the rapid development of hybrid vehicles and pulse power boosting technology. In this work, the novel environment-friendly (1-x)(Ba_0.8Sr_0.2)TiO₃-xBi(Zn_2/3Nb_1/3)O₃ (0.04 ≤ x ≤ 0.16) [(1-x)BST-xBZN] ceramics were designed and synthesized by traditional solid-state reaction method, exhibiting ultrahigh energy efficiency and super stability against temperature. The results show that the recoverable energy density (W_rec) and the energy efficiency (η) of the (1-x)BST-xBZN ceramics are increase sharply then decrease slightly with increasing of x value. The 0.88BST-0.12BZN ceramic demonstrated a recoverable energy density of ≈ 1.62 J/cm³ and an extreme high energy efficiency of ∼ 99.8 % at 225 kV/cm at room temperature. These extreme high efficiency and high breakdown strength would make (Ba,Sr)TiO₃-based lead-free ceramic systems might be good candidate for high power energy-storage applications pulsed power systems.     

Low temperature sintering of iron deficient Z type hexagonal ferrites

Low temperature sintering of iron deficient hexagonal Co₂Z type ferrites is attempted to prepare a chip inductor for ultra high frequency uses. It should be attained below the melting point of silver (960 °C) used as the electrode material of the chip inductor. The best result is obtained for the sample with the composition 2.15Co_0.6Cu_0.4O·3Ba_0.79Sr_0.16Bi_0.05O·9.725Fe₂O₃ sintered at 925 °C containing 0.5 wt.% of lithium bismuth oxide as a sintering additive. Its density and permeability reaches 5.0 g/cm³ and 7, respectively. As a result, the impedance of the chip inductor also reaches 390 ohm at 2 GHz using this material.     

基于连通管原理的桥梁挠度检测

基于连通管原理,采用硅压阻式压力传感器、温度传感器、RS485通讯技术和计算机技术,设计了一种桥梁挠度自动检测系统,对桥梁的状态进行一定的预测,如果遇到严重的沉降事故能及时预警。实测数据表明本系统稳定可靠,同时检测精度可达1 mm,满足桥梁挠度长期检测的要求。     

两种TDOA定位算法在水声被动定位下的精度分析

介绍了TDOA的两种算法:Chan算法和Taylor算法,并针对Taylor算法的缺点,引入一种改进的Taylor算法,并将其在水声被动定位系统中进行了仿真和性能比较,从最终仿真结果中得出较适合实际水下信道的定位算法。     

Characteristics of 10-Gb/s Electroabsorption Modulator Integrated Distributed Feedback Lasers for Long-Haul Optical Transmission Systems

In this study, we review the characteristics of 10-Gb/s electroabsorption modulator integrated (EAMI) distributed feedback (DFB) lasers for long-haul optical transmission systems. The recent progress and issue of extinction ratio, chirp, and frequency response are described, which are important parameters to improve transmission performance. Except for the extinction ratio, frequency response and chirp characteristics are discussed further. The frequency response of packaged EAMI-DFB lasers has been improved using the novel impedance matching technique. The large signal chirp characteristics are calculated with varying bias voltage, facet reflectance, grating phase, and a coupling coefficient (κL) to predict the measured chirp characteristics. Finally, transmission performance (BER, eye margin, and eye opening penalty) is measured and estimated using the calculated chirp characteristics.     

Non-ergodic – ergodic transition and corresponding electrocaloric effect in lead-free bismuth sodium titanate-based relaxor ferroelectrics

The ferroelectric refrigeration technology based on electrocaloric effect (ECE) is a promising environmental way to replace the gas compression refrigeration. Lead-free bismuth sodium titanate (NBT)-based relaxor ferroelectric ceramics have advantages of a large ECE within a wide temperature range around the depolarization temperature (T_d), but the T_d of pure NBT is too high to meet the application requirements. Here, we systematically studied the electrocaloric effect in (0.95-x)(Na_0.5Bi_0.5)TiO₃-0.05SrTiO₃-x(K_0.5Na_0.5)NbO₃ ((0.95-x)NBT-0.05ST-xKNN) ceramics and its relation with the relaxor behavior. The addition of KNN enhances the relaxor character, and shifts the T_d from 120 °C to a low temperature even below 0 °C. The directly measured ECE shows a peak of high ?T_max = 0.88 K (@ 60 °C) for x = 0.05 under an electric field of 40 kV/cm and a wide temperature span of 79 °C (≥ 80% of ?T_max). The x = 0.07 sample exhibits the optimal room-temperature ECE performance with a high ?T_30 °C = 0.71 K because the non-ergodic – ergodic phase transition occurs near room temperature. The electric field–temperature phase diagram reveals the origin of the enhanced ECE as the electric-field-induced transition between polar nanoregions (PNRs) and long-range ferroelectric domain.     

基于样条插值的液晶空间光调制器衍射效率优化方法研究

针对液晶空间光调制器阵元间相位调制量偏差降低光束衍射效率的问题,提出基于样条插值的液晶空间光调制器衍射效率优化方法。依据泰曼-格林干涉原理,搭建了相位调制系统。对调制器加载阶梯变化的灰度图,通过计算干涉条纹移动量,绘制液晶空间光调制器相位调制曲线。采用三次样条反插值法对相位调制曲线进行校正,实现对相位调制量的相位补偿。搭建液晶空间光调制器衍射效率测试系统,对所提优化方法进行实验验证,并与随机梯度下降法进行了对比。结果表明:当光束偏转角度为1.56°、0.78°、0.39°、0.19°时,文中所提方法提高了30%~40%的光束衍射效率,相较于随机并行梯度下降法,衍射效率提高了2%~8%。该方法有效抑制了栅瓣能量,提升了主瓣光束衍射效率,克服了随机并行梯度下降法迭代次数多,优化速度慢,易陷入局部最优的缺点。     

Assessment of visual fatigue caused by stereoscopic disparity based on multimodal measurement

Given the prevalence of visual fatigue induced by stereoscopic display, research on the neural mechanism of visual fatigue was limited. The goal of this study was to investigate the effect of stereoscopic display with different horizontal disparities on visual fatigue based on subjective questionnaire, ophthalmological parameters, eye movement and electrocardiogram (ECG). Subjects felt more headache, uncomfortable and dry eyes after watching 70-minute enhanced 3D display with larger negative disparity than normal 3D display. Meanwhile, visual function tear film break-up time (TBUT) reduced, microsaccade mean pupil diameter (MMPD) increased and heart rate variability (HRV) changed more significantly after watching enhanced 3D display. Overall, these results demonstrated that enhanced 3D display had a better sense of immersion, but it induced more visual fatigue significantly than normal 3D display.