Suppression of high-temperature dielectric loss by designed thermal annealing treatment in (Bi1/2Na1/2)TiO3 ceramics

Dielectrics for automobile applications generally require high temperature reliability. Bi_1/2Na_1/2TiO₃-based materials are excellent high-temperature dielectric candidates with relatively large temperature-insensitive dielectric responses and a maximum dielectric permittivity temperature as high as 300 °C. However, they suffer from a high dielectric loss that increases exponentially above 200 °C due to ionic conduction from thermally activated oxygen vacancy migration. Here, we demonstrate that the impact of ionic conduction on dielectric loss can be effectively suppressed by introducing a sodium deficiency and thermal annealing An appropriate combination of both treatments elevated the temperature insensitivity of the dielectric loss up to ～ 300 °C. A systematic investigation using impedance spectroscopy correlated with microstructure analysis revealed that the sodium deficiency and thermal annealing affected the mobile oxygen vacancy concentration differently.     

1400F铝带轧机板形缺陷识别处理

要对铝带材的板形进行有效的控制,必须对实际的板形进行识别,以判断当前带材板形的缺陷模式,才能有效的利用轧机装备的板形控制装置对板形实施控制。本文通过最小二乘法,建立板形缺陷的识别理论,并根据实际数据和现场应用,证明了该理论的可行性。     

管线断裂失效概率模型及计算

以相关管道档案、检验报告作为原始资料, 配合现场调查及观测, 采用“ 在役压力管道失效风险分析系统(SAPP)” , 对管线断裂失效风险进行分析。将管线中各缺陷安全状况与失效风险有机地结合起来, 在当前检测缺陷数据基础上, 通过适当选取概率模型, 计算管线的失效风险概率。对于准确了解管线的安全状态, 制定具有针对性的检修计划, 加强管线维护, 保障装置的安全稳定运行有重要的现实意义。     

Native point defects and oxygen migration of rare earth zirconate and stannate pyrochlores

Various excellent properties of rare earth zirconate and stannate pyrochlores are close related with their native point defects.First-principles calculations are performed to systematically investigate the point defect mechanism and the oxygen diffusion behavior of A2B2O7 (A=La,Ce,Pr,Nd,Pm,Sm,Eu,Gd;B=Zr,Sn).The possible defect complexes and their associated reactions under stoichiometric and nonstoichiometric conditions are explored.The O Frenkel pairs are the most stable defect structure in stoichiometric zirconates,whereas the cation antisite defects are the predominant one in stoichiometric stannates.In the case of BO2 excess zirconates and stannates,the BA cation antisite defect with the A vacancy and/or the oxygen interstitial is energetically favorable,whereas the AB antisite defect together with the oxygen vacancy and/or the A interstitial is preferable under the A2O3 excess condition.Meanwhile,the maximum point defect concentrations of zirconates are much higher than those of stannates.Furthermore,the oxygen migration barriers are similar in these compounds,ranging in 0.68 eV-0.80 eV.The predicted point defects and oxygen diffusion mechanisms play the critical role in their engineering applications and are expected to guide the future property improvement of pyrochlores through the control of point defects and/or composition.     

1 000m3轻烃球罐焊接缺陷成因分析及对策

对两台1 000m3轻烃球罐焊接缺陷产生的原因进行分析,并提出了相应的解决措施。     

场量测量在变交漏磁检测技术中的应用

介绍了以AD637为基础建立的交变漏磁场测量调理电路,完成了基于A3515霍尔元件的漏磁场场量测量传感器的设计,阐述了交变漏磁场测量的工作原理和测试方法,通过对钢管矩形裂纹的测试结果表明,该设计实现了测试的目的,在对缺陷信号进行分析和处理的基础上,提出了基于"缺陷环"的识别方法.     

Topological domain-engineered antiferroelectric-like behavior with enhanced energy storage properties in ferroelectric hexagonal Cr-doped YMnO3

We present the observation of the peculiar antiferroelectric (AFE)-like behavior, characterized by the polarization-electric field (P−E) double hysteresis loops and zero remnant polarization (P_r), in the ferroelectric (FE) Cr-doped YMnO₃ (YMCO) single crystals. The AFE-like behavior in YMCO is in sharp contrast with the FE P−E single loop with high P_r in the undoped YMnO₃ (YMO). The topological cloverleaf domains with ferroelectricity are observed in both YMO and YMCO. It is revealed unambiguously that the AFE-like behavior in YMCO arises from the Cr-substitution induced domain pattern transition from type-II with nonzero net macroscopic polarization to type-I with zero net polarization, as well as the recoverable type-I domain pattern after electric field sweeping. In addition, it is found that both the recoverable energy density and energy storage efficiency are significantly enhanced due to the AFE-like behavior in YMCO compared to YMO. Our results suggest for the first time that, in addition to the mechanism of the antiparallel arrangement of adjacent electric dipoles, the AFE-like behavior can be also achieved by domain engineering in a FE, which provides a possible new strategy to obtain high energy storage performance.     

基于图像线灰度和BP神经网络的织物疵点检测

探讨织物疵点自动检测的方法。通过对4种常见织物疵点的图像进行线灰度曲线分析和处理,提取疵点图像的特征值,送入BP神经网络进行识别,从而实现织物疵点的检测。试验结果表明,该方法取得了较好的检测效果,织物疵点识别率达到93%以上。认为,此法能够有效识别出织物中的几类常见疵点,应进一步研究,以提高其识别准确率。     

语音录入系统在针织成品检验中的应用

介绍纺织面料成品检验语音输入系统的方案设计,通过语音识别与合成技术构建语音录入系统,通过自适应学习提高识别效率。阐述通过成品检验环境噪音测试、验布工人声音采集建立语音系统,以及该系统在语音验布上的应用。经过应用测试显示,使用语音系统代替手写录入可使疵点检验率从57%提升到73%。在针织成品检验中采用语音录入系统能够快速录入疵点信息,提高检验效率,进一步简化验布工操作流程,降低漏验和堵布风险,提高面料整体的质量控制能力。     

95氧化铝瓷排蜡工艺常见缺陷及解决措施

简述了陶瓷排蜡工艺及其原理 ,分析了实际生产中常见的缺陷 ,提出了解决排蜡缺陷的相关措施