一种基于NFC的无源智能锁及其在配电网中的应用

针对配网柜体采用的传统机械锁具管理难度大、破解容易以及可追踪性差,无法满足现代电网快速发展的多样化需求等问题。该文研制了一种基于配电物联网架构的无源高可靠性智能电子锁。其内嵌安全芯片,采用近场通信(Near Field Communication,NFC)技术完成通信及取能,无需机械钥匙开锁,无需维护更换锁具电池,并配套开发了能够实时监测锁具状态、储存开锁信息的智能锁管理系统以及配合开锁APP使用的电子钥匙,分析了智能锁具的硬件设计及系统的应用流程。最后,通过实践应用表明,该套锁具系统在运维便捷、信息安全和科学管理方面具有明显效用。     

Effect of Gravity on the Hydrodynamics in an Unbaffled Stirred Vessel

The hydrodynamics in an unbaffled stirred vessel were simulated in order to highlight the effect of gravity on pressure and velocity distributions. Two fluids with different viscosity were studied for the laminar and turbulent flow regimes, respectively. The simulation results were compared with experimental data from the literature. Results indicate that for the higher‐viscosity fluid, gravity only affects static pressure and that the effects of gravity on velocity and dynamic pressure are negligible. For the lower‐viscosity fluid, however, gravity imposes a pronounced impact on static pressure, dynamic pressure, velocity, and turbulent kinetic energy. These findings indicate that careful consideration is necessary for the role that gravity plays in the study of free‐surface hydrodynamics in unbaffled stirred vessels.     

Deployment simulation of membrane structures based on elastic-plastic behavior parameterization of the crease

Journal of Mechanical Science and Technology - Aiming at the problem that the membrane structure is prone to creases in the process of folding and compaction, a proxy model is used to replace the...     

Flame characteristics of premixed H2-air mixtures explosion venting in a spherical container through a duct

The explosion venting duct can effectively reduce the hazard degree of a gas explosion and conduct the venting energy to the safe area. To investigate the flame quantitative propagation law of explosion venting with a duct, the effects of hydrogen fraction and explosion venting duct length on jet flame propagation characteristics of premixed H₂-air mixtures were analyzed through experiment and simulation. The experiment results under initial conditions of room temperature and 1 atm show that when hydrogen fraction was high enough, part of the unburned hydrogen was mixed with air again to reach an ignitable concentration, resulting in the secondary combustion was easier produced and the duration of the secondary flame increased. With the increase of venting duct length, the flame front distance and propagation velocity increased. Meanwhile, the spatial distribution of pressure field and temperature field, and the propagation process and mechanism of the flame venting with a duct were analyzed using FLUENT software. The variation of the pressure wave and the pressure reflection oscillation law in the explosion venting duct was captured. Therefore, in the industrial explosion venting design with a duct, the hazard caused by the coupling of venting pressure and venting flame under different fractions should be considered comprehensively.     

水泥工厂预均化堆场的智能化改造方案

正0前言预均化堆场自上世纪六十年代在世界水泥工业应用以来,已在全球广泛采用,并对提高生产效率,实现工厂自动控制,减小生产的波动,提高产品的质量都作出了很大的贡献。但预均化堆场普遍存在着工作环境恶劣,粉尘污染严重,设备故障率较高等问题。因此,通过对其智能化改造来克服这些不足,对于进一步实现水泥工业由大到强的进步,实现节能降耗、绿色环保和优质高效的生产目标具有重大的意义。1智能化改造内容     

水泥厂堆取料机轨道梁设计优化及安装

正0前言近年来苏州中材建设有限公司承建了多条海外5 000 t/d水泥熟料生产线EPC总承包项目。原燃料堆场多采用圆型堆场或长型堆场,例如400 m长型辅助原料堆场有约1 600 m轨道梁、4 200多支螺栓,直径Φ90 m圆型堆场有约282 m轨道梁、1150支螺栓,合计共有约5 350多支螺栓需要安装,燃料为煤的生产线,工作量更是庞大。堆取料机轨道行程较长,对固定轨道螺栓的安     

我公司延长耐火砖寿命的工艺管理措施

正0引言我公司有两条2 500 t/d的熟料生产线,于2000年先后投产,现正常生产,随着近年来对耐火材料使用的技术攻关和精心管控,烧成带窑砖使用寿命超过40个月。下面就我公司的延长耐火砖寿命的工艺管理措施进行介绍,供借鉴研讨。     

Novel barium titanate based ferroelectric relaxor ceramics with superior charge-discharge performance

Lead-free 0.9BaTiO₃-0.1(Bi_0.9Na_0.1)(In_0.8Zr_0.2)O₃ (0.9BT-0.1BNIZ) ferroelectric relaxor ceramic was synthesized by solid-state reaction method. A dense microstructure and fine grain size was obtained with addition of BNIZ content. The dielectric behaviors indicated the dominance of ergodic relaxor phase. The 0.9BT-0.1BNIZ ceramic was found to possess an enhanced recoverable energy density (W_R～1.33?J/cm³) and efficiency (η～88%) under 18?kV/mm at room temperature. What’s more, W_R is maintained ≥0.53?J/cm³ with η?≥?94% under 10?kV/mm and the variation of W_R is less than 15% over 25～140?°C. The high stability of energy storage properties is mainly ascribed to the characteristics of ergodic relaxor phase. The stored energy was released in sub-microseconds (～0.19?μs). The superior current density (C_D～796?A/cm²) and the power density (P_D～39.8?MW/cm³) were obtained simultaneously. The enhanced W_R and the superior charge-discharge performances strongly demonstrate that the BT-based ceramics are promising candidates of high-power pulse capacitor applications.     

Mechanism of significantly enhanced piezoelectric performance and stability in textured potassium-sodium niobate piezoelectric ceramics

In this study, the piezoelectric coefficient d₃₃ and planar electromechanical coupling coefficient k_p were enhanced 145% and 71%, respectively for the <001>-textured (K_0.5Na_0.5)_0.95Li_0.05Nb_0.93Sb_0.07O₃ piezoelectric ceramics compared with their randomly oriented counterpart. Significantly enhanced piezoelectric response in textured ceramics is originated from a combined effect of the intrinsic high piezoelectric activity of <001>-oriented grains in the tetragonal-orthorhombic phases, and easy polarization rotation of fine domains. Furthermore, a comparative analysis suggests that <001>-textured ceramics exhibit good thermal stability, benefiting from the weakened depolarization behavior via crystal orientation. The superior fatigue resistance in textured ceramics can be attributed to the reduced clamping effect as low defect density. These results show that high-performance textured ceramics reported in this work will be promising candidates in the field of lead-free piezoelectric materials.