Good dielectric performance and broadband dielectric polarization in Ag,Nb co-doped TiO2

Due to the demand of miniaturization and integration for ceramic capacitors in electronic components market, TiO₂-based ceramics with colossal permittivity has become a research hotspot in recent years. In this work, we report that Ag⁺/Nb⁵⁺ co-doped (Ag_1/4Nb_3/4)_xTi_1−xO₂ (ANTOx) ceramics with colossal permittivity over a wide frequency and temperature range were successfully prepared by a traditional solid–state method. Notably, compositions of ANTO0.005 and ANTO0.01 respectively exhibit both low dielectric loss (0.040 and 0.050 at 1 kHz), high dielectric permittivity (9.2 × 10³ and 1.6 × 10⁴ at 1 kHz), and good thermal stability, which satisfy the requirements for the temperature range of application of X9R and X8R ceramic capacitors, respectively. The origin of the dielectric behavior was attributed to five dielectric relaxation phenomena, i.e., localized carriers' hopping, electron–pinned defect–dipoles, interfacial polarization, and oxygen vacancies ionization and diffusion, as suggested by dielectric temperature spectra and valence state analysis via XPS; wherein, electron-pinned defect–dipoles and internal barrier layer capacitance are believed to be the main causes for the giant dielectric permittivity in ANTOx ceramics.     

Influence of CO2 inleakage on the slight-alkalization of generator internal cooling water

The slight-alkalization of generator internal cooling water (GICW) is widely used to inhibit the corrosion of hollow copper conductor and thereby ensure the safe operation of the generator. CO₂ inleakage is increasingly identified as a potential security risk for GICW system. In this paper, the influence of CO₂ inleakage on the slight-alkalization of GICW was theoretically discussed. Based on the equilibriums of the CO₂-NaOH-H₂O system, CO₂ inleakage saturation was derived to quantify the amount of the dissolved CO₂ in GICW. This parameter can be directly calculated with the measured conductivity and the [Na⁺] of GICW. The influence of CO₂ inleakage on the slight-alkalization conditioning of GICW and the measurement of its water quality parameters were then analyzed. The more severe the inleakage, the narrower the water quality operation ranges of GICW, resulting in the more difficult the slight-alkalization conditioning of GICW. The temperature calibrations of the conductivity and the pH value of GICW show non-linear correlations with the amount of CO₂ inleakage and the NaOH dosage. This study provides insights into the influence of CO₂ inleakage on the slight-alkalization of GICW, which can serve as the theoretical basis for the actual slight-alkalization when CO₂ inleakage occurs.     

超细粉在内循环流化床中的流态化特性

在内径120 mm的半圆柱形内循环流化床中,以平均粒径387 nm的Ti O2为原料,考察了单独通入流化气、射流气和同时通入流化气和射流气三种流化方式下超细粉的流化特性以及射流气速对超细粉聚团尺寸的影响。结果表明:同时通入流化气和射流气时,流化气能促进粉体循环,消除环隙死区;高速射流能有效破碎聚团,显著减小聚团尺寸,从而使超细粉在环隙区与导流管之间形成稳定循环,小聚团在环隙区实现平稳流态化。随着射流气速的增大,聚团尺寸减小,粒度分布变窄,在射流气速分别为60,90,120,150 m/s的条件下,聚团平均直径分别为194,158,147,135μm。     

埋地管道泄漏内封堵装置设计与研究

针对流体输送埋地管道泄漏问题,设计了一种利用管道机器人携带封堵气囊进行快速应急封堵修复的埋地管道泄漏内封堵装置。采用矩阵变换方法建立了牵引系统驱动轮过弯方程,利用MATLAB软件对过弯方程进行了验证,同时利用ADAMS软件仿真分析过弯路径与驱动轮转角对牵引系统行走速度的影响。研究结果表明:由两个串联封堵器组成的应急封堵系统可满足复杂工况下的管道泄漏封堵要求;牵引系统驱动轮在弯管内部行走时,单轮速度呈周期性变化,但三个驱动轮整体周期运动特性一致;驱动轮转角在25°~40°时,牵引系统行走速度与驱动轮转角成正比,且转角为30°时驱动效果最好。该内封堵装置的结构设计可为管道泄漏应急封堵领域装备的研发提供重要参考。     

Animations showing Lego manipulative tasks: Three potential moderators of effectiveness

Evidence suggests that transient visual information, such as animations, may be more challenging to learn than static visualizations. However, when a procedural-manipulative task is involved, our evolved embodied cognition seems to reverse this transitory challenge. Hence, for object manipulative tasks, instructional animations may be more suitable than statics. We investigated this argument further by comparing animations with statics using a Lego task shown to university students, by examining three potential moderators of effectiveness: (a) the environment of manipulation (virtual or physical), (b) the quality of visual information (focused or unfocused), and (c) the presence of hands (no hands or with hands). In Experiment 1 we found an advantage of animation over statics, and no differences among the environments. In Experiment 2, we again observed an animation advantage, a small advantage of focused static information compared to unfocused static information, and a positive effect of not showing the hands.     

浅议我国上市公司内部控制环境优化

控制环境是内部控制框架的基础,由于我国目前上市公司内部控制体系建设尚处于初级阶段,决定了其内部控制环境呈现出固有弊端.分析了我国上市公司在控制环境方面存在的缺陷,并提出了相应的优化措施,以期能对内部控制环境的完善起到一定的作用.     

反凝析现象对雅克拉凝析气处理工艺的影响

雅克拉凝析气田位于塔里木盆地北部，地处新疆维吾尔自治区阿克苏地区境内，它是中国石化集团公司西北分公司探明并投入开发的最大凝析气田，采用衰竭式开采。通过对井口物流的相态研究，认识了凝析气的反凝析规律，采取了提高凝析气中C^＋₃收率的方法，以确保外输干气的烃露点达到管输要求，并提高该气田开发的经济效益。在工艺方案设计过程中，通过多种工艺方案比选，确定选用膨胀机进口压力为6.0 MPa的膨胀机制冷工艺， C^＋₃收率达到92％以上，外输干气烃露点满足管输要求。     

汽车内燃机油的现状及发展趋势

从汽车内燃机润滑油的性能和质量与设计制造技术。环保，节能的关系出发，论述了国内外汽车内燃机润滑油性能和质量的现状和发展趋势，提出了提高我国汽车内燃机润滑油性能和质量的思考。     

A concept for the generation of out-of-plane distortion from tailored FRP laminates

The phenomenon of thermally induced distortions in unsymmetrical laminates is well understood, and it may be shown that a square, unsymmetrical 0.90 laminate will tend to form two stable geometries with a snap-through phenomenon between them. This paper discusses laminates in which at each point the lay-up is symmetrical across the laminate mid-plane, but which still exhibit multiple stable geometries. The number of stable geometries can be controlled by the details of the lay-up from the minimum of two to, in principle, an unlimited number. In addition it will be shown how a similar process can be used to generate multiple stable stress states and geometries in unidirectional laminates. This paper represents a very preliminary experimental investigation of the design space available for such composite laminates. Possible applications of composites with multiple stable geometries are noted.     

复混肥料中钾含量的测定

根据作者多年工作经验，详细介绍了复混肥料中钾合量的到定，且与标准GB／T8574—1988进行了逐一比较。