Reinvestigation of the photostrictive effect in lanthanum-modified lead zirconate titanate ferroelectrics

Photostriction of lanthanum-modified lead zirconate titanate (PLZT) was commonly attributed to the combination of anomalous photovoltaic effect and inverse piezoelectric response. Herein, distinct photostrictions are detected in both poled and unpoled PLZT ceramics under 405 and 520 nm laser illuminations. The maximum photostriction around 0.09% is obtained in unpoled PLZT under 405 nm illumination, which is nine times of previously reported value that deduced from poled PLZT. The photoelectric and photovoltaic characterizations of poled/unpoled PLZT further evidence that the detected photostriction shows no direct association with the photovoltage-induced inverse piezoresponse. The light-induced microstructure changes observed by in situ piezoelectric force microscopy are revealed by domain evolutions along the boundaries. The possible photostriction mechanism of PLZT is attributed to the strong photo-induced electron-lattice coupling, which is suggested by the light-induced changes of the Zr/Ti-O-Zr/Ti bonds reflected by the power-dependent Raman spectra. This study extends the photostriction of PLZT to visible light range and will also stimulate reappraisal of the underlying mechanism of photostrictive effect involving ferroelectrics.     

基于ANSYS FLUENT的超深井长距离膏体充填管道输送模拟研究

为研究超深井长距离膏体充填管道自流输送问题,根据云南某矿山实际充填管路采用Gambit建立三维数值模型,用ANSYS FLUENT软件进行数值模拟计算,以水平管道和弯管为例研究了不同配比、浓度和流量下的管道压力、流速变化规律和管道阻力损失之间的关系。通过井下工业环管的压力监测系统,统计分析矿山井下实际管道压力监测值,井下实际监测结果和采用ANSYS FLUENT软件三维数值模拟研究结果较为接近,表明ANSYS FLUENT软件模拟超深井长距离膏体充填管道输送是可行的,研究结果可为矿山实现超深井、长距离、大倍线条件下膏体充填管道输送提供技术支持。     

Investigating the influence mechanism of hydrogen partial pressure on fracture toughness and fatigue life by in-situ hydrogen permeation

In this work, we investigate the influence mechanism of hydrogen partial pressure on fracture toughness and fatigue life of a high strength pipeline steel. Both fracture toughness test and fatigue life test are carried out under different hydrogen partial pressure. The experimental results show that with the increasing of hydrogen partial pressure, fracture toughness and fatigue life decrease and the decrease trends gradually flatten out. Hydrogen has a larger effect on fatigue life than fracture toughness. Only 3% hydrogen gas can cause a 67.7% decrease of fatigue life. The in-situ hydrogen permeation test is performed respectively in 2 MPa, 5 MPa and 8 MPa hydrogen partial pressure. With the increasing of hydrogen partial pressure, the increase trend of hydrogen permeation current gradually tends to be gentle, which indicates that the hydrogen atoms entering into the material gradually become saturated. This result can be used to clarify the influence mechanism of hydrogen partial pressure on fracture toughness and fatigue life.     

Effects of oxygen concentration on the macroscopic characteristic indexes of high-temperature oxidation of coal

To explore the macroscopic characteristic indexes for oxidation of coal under high-temperature conditions, an XKGW-1-type high-temperature-programmed heating experimental system was constructed. Tests on high-temperature oxidation of coal under high-temperature conditions at five oxygen concentrations of 21, 17, 13, 8, and 3 vol% were independently conducted. Laws of variation in high-temperature oxidation of coal indices, such as the coal temperature, gas ratios, rate of oxygen consumption, and exothermic strength from indoor temperature to 500 °C, were investigated at those oxygen concentrations. The results showed that the variation tendencies of characteristic indices for high-temperature oxidation of coal at different oxygen concentrations were extremely intricate. At the five oxygen concentrations, the rate of oxygen consumption increased rapidly with an increase in coal temperature and eventually remained at a higher range. The rate of oxygen consumption increased with temperature with an approximate exponential trend at the five oxygen concentrations tested. For the same coal temperature, the rate of oxygen consumption decreased with the oxygen concentration. The variation tendencies of the CO and CO₂ production rates were similar, both increased rapidly with an increase in coal temperature in the early stages and reached a maximum at a coal temperature of 380 °C. They decreased slightly with an increase in coal temperature at first and increased promptly thereafter. The concentrations of CH₄, C₂H₄, and C₂H₆ first increased with an increase in the coal temperature and markedly decreased after the maximal value. The temperatures for the extreme points were 480, 410, and 420 °C for CH₄, C₂H₄, and C₂H₆, respectively. The trends of the macroscopic characteristic indexes throughout the process of high-temperature oxidation of coal in a certain temperature range at various oxygen concentrations can be used for temperature prediction and fire prevention during coal mining.     

Unbalanced probabilistic linguistic decision-making method for multi-attribute group decision-making problems with heterogeneous relationships and incomplete information

Artificial Intelligence Review - In group decision-making problems, decision makers prefer to use several linguistic terms to describe their own perception and knowledge, and give their preference...     

The crosslinking directing dynamic behavior of polymer latex under the investigation toward waterborne damping coatings

Latex polymers with precisely designed dynamic mechanical behavior are the key for waterborne damping coatings, which are widely desired in noise and vibration reduction with additional environmental benefits. In this work, we synthesized series of polymer latexes with various crosslinking agents (CA) and network distributions through the control on emulsion polymerization processes. We have revealed that the variation on crosslinking can significantly direct the latex behavior under dynamic conditions as well as its films. The variables involve the CA composition, the functionality, the crosslinking manner, the hydrophilic-hydrophobic feature as well as the feeding method. Although all the latex films showed the damping peaks locating in the range from −10 to 70°C, their damping behaviors were quite different. Suggested by the empirical parameters of LA and TA, the product from sequential monomer feeding method tended to give good extensional damping performance. Especially when the crosslinking of diacetone acrylamide (DAAM)/adipic dihydrazide was applied, there was a linear increase on LA with the increasing dosage of DAAM from 0 to 10 mmol in the final monomer addition batch. Meanwhile, good constrained layer damping is expected on the products from the power monomer feeding method with the maximum CA dosage shown below 7.5 mmol. The best TA was achieved when the CA of divinylbenzene was used in the dosage of 5 mmol. These results would be valuable to be referenced in the engineering on organic damping materials toward modern industrial and vehicles applications.     

一种最小变形度全景视频映射方法

全景视频需要经过采样映射转换成平面矩形视频,以便后续的压缩编码.针对现有映射方法存在的内容变形和采样不均匀问题,提出一种最小变形度映射方法(Minimum Deformation Projection,MDP).首先提出新的变形度计算公式求得最优解,其次结合像素排列为矩形的要求和人工边界等因素对最优解做近似,最后得到了最优的多边形映射形状和像素排列方案.实验数据表明,MDP的采样密度更均匀,结合使用x265,相对于ERP可以获得约14.47％的增益,优于其他映射方法.     

深基坑护坡桩垂直安全防护施工技术

北京市通州区运河核心区04地块基坑施工中,针对超期服役的护坡桩结构,采用刚柔结合的防护措施及施工工艺,解决了深基坑护壁结构开裂、脱落带来的施工困难,保证了地下结构施工人员的安全,大幅度节约了地下结构外墙施工的成本.