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1.
以糖厂发配电系统的实际配置为基础,对现有采样算法进行对比分析,选取适用的电压、电流、频率等参数的采样算法;对比研究了国内外相关孤岛检测技术,基于单机-无穷大运行模型,研究了自备热电厂发电机组的负荷极限;确定了外部主网故障防自备电厂孤岛效应的解列条件以及继电保护逻辑;对自备电厂用电负荷进行分级,据此确定低频减载判据,最后确定了自备电厂频率保护整定策略的工程实施。  相似文献   
2.
采用多体动力学仿真软件RecurDyn的履带车辆子系统Track(LM)建立履带式电传动推土机多体动力学模型,通过Ground模块建立地面模型,并对其在干砂路面和黏土路面工况下直线推土作业进行了动力学仿真,研究分析了推土机在不同作业工况下整机的质心、履带接地长度、履带接地比压和滑转率随切土深度的变化规律,以及推土机在推土工况下的负载特性,提出通过对推土机质心的合理布置,能使接地比压均布,从而提高推土机工作稳定性的结论,为电传动推土机的底盘设计和传动系统的优化奠定基础。  相似文献   
3.
In this work, we developed a novel system of isovalent Zr4+ and donor Nb5+ co-doped CaCu3Ti4O12 (CCTO) ceramics to enhance dielectric response. The influences of Zr4+ and Nb5+ co-substituting on the colossal dielectric response and relaxation behavior of the CCTO ceramics fabricated by a conventional solid-phase synthesis method were investigated methodically. Co-doping of Zr4+ and Nb5+ ions leads to a significant reduction in grain size for the CCTO ceramics sintered at 1060 °C for 10 h. XRD and Raman results of the CaCu3Ti3.8-xZrxNb0.2O12 (CCTZNO) ceramics show a cubic perovskite structure with space group Im-3. The first principle calculation result exhibits a better thermodynamic stability of the CCTO structure co-doped with Zr4+ and Nb5+ ions than that of single-doped with Zr4+ or Nb5+ ion. Interestingly, the CCTZNO ceramics exhibit greatly improved dielectric constant (~105) at a frequency range of 102–105 Hz and at a temperature range of 20–210 °C, indicating a giant dielectric response within broader frequency and temperature ranges. The dielectric properties of CCTZNO ceramics were analyzed from the viewpoints of defect-dipole effect and internal barrier layer capacitance (IBLC) model. Accordingly, the immensely enhanced dielectric response is primarily ascribed to the complex defect dipoles associated with oxygen vacancies by co-doping Zr4+ and Nb5+ ions into CCTO structure. In addition, the obvious dielectric relaxation behavior has been found in CCTZNO ceramics, and the relaxation process in middle frequency regions is attributed to the grain boundary response confirmed by complex impedance spectroscopy and electric modulus.  相似文献   
4.
研究了常规铸轧过程中施加20、50和150Hz频率,电流强度为400A的脉冲电流对Al-6Zn-3Mg-2Cu合金铸轧板的组织及力学性能的影响。结果表明,经20Hz的脉冲电流处理后,Al-Zn-Mg-Cu合金铸轧板偏析情况大为改善,微观组织显著细化;150Hz脉冲电流对铸轧板的组织影响不大;铝合金中τ相广泛分布,呈网状或岛状;同时,经20Hz脉冲电流处理的铸轧板抗拉强度可达320MPa,是常规铸轧板强度的1.3倍;样品具有脆性断裂特征,脉冲处理后韧性有所提高。  相似文献   
5.
Pulsed laser deposition (PLD) was used to prepare tungsten trioxide (WO3) films on ITO substrates with a varying laser power density of 4.0–5.5 W/cm2. XPS indicated that when the laser power density decreased, the peak positions of the W 4f and O 1s orbits shifted slightly to low energy due to the difference in oxygen vacancies. As the laser power density decreased, W6+ gradually replaced the lattice position of O2?, increasing oxygen vacancies in the lattice. The transmittance modulated values (ΔT) were over 44% at 830 nm, indicating strong absorption by the WO3 thin films in the near-infrared ray. The switching time of the WO3 thin films between bleached states and coloured states decreased as the laser power density increased due to the amorphous structure, morphology, and lower oxygen deficiency at a high power density. The high ΔT and very fast switching time of tb (1.09 s) and tc (6.01 s) demonstrated the excellent electrochromic (EC) properties of the WO3 films prepared by PLD.  相似文献   
6.
7.
《Ceramics International》2021,47(24):34521-34528
Aiming at the problem that power density and energy density are difficult to obtain simultaneously under low field, a novel composition (1-x)Na0·5Bi0·5TiO3-xBaZn1/3Ta2/3O3((1-x)NBT-xBZT) was designed and fabricated via solid-state methods. With the addition of BZT, the crystal lattice, structural symmetry, grain size, and dense degree were all increased proved by XRD, Raman, and Archimedes drainage method et al. Because of the enhancement of relaxor behavior, the x=0.10 sample displayed a high permittivity εr of 2871±15% and a low dielectric loss tan δ ≤ 0.025 in the wide temperature range of 60–400 oC. This ceramic also showed maximum recoverable energy density Wd (2.07 J/cm3) with high efficiency η (71.5%) under a low field of 150 kV/cm. Moreover, pulse discharge testing proved that this ceramic possessed both a significant discharge energy density WD (0.96 J/cm3) and a record high power density PD (108.54 MW/cm3). This work provided a promising material for high power and energy applications.  相似文献   
8.
基于ANSYS Workbench的RV减速器随机振动分析   总被引:1,自引:0,他引:1  
以RV减速器为研究对象,建立了RV减速器的三维模型,导入Adams中进行运动学仿真,得到了正齿轮的加速度;利用ANSYS Workbench求解得到RV减速器的固有频率,根据概率统计学分析技术推导功率谱密度函数;最后,将功率谱密度峰值提取后导入ANSYS Workbench的Random vibration模块作随机振动分析。该方法考虑了随机振动因素对机构应力以及安全裕度的影响,为处理RV减速器工作可靠性问题提供了一种新的方法。  相似文献   
9.
随着新能源汽车的发展,动力电池成为纯电动汽车的核心技术之一。为使电池热管理系统对车用电池组温度的控制过程更加节能高效,采用合适的电池布置间距尤为重要。以26650圆柱形锂离子电池组为对象,通过Fluent仿真模拟了顺排与叉排两种布置形式下28mm、31mm、34mm、37mm、40mm五种电池间距对应的电池组强制风冷过程。分析了五种电池布置间距下电池综合换热性能、电池最高温升、电池温度一致性、所需风扇功率及电池组体积利用率随电池间距的变化规律。研究表明权衡考虑各项性能的最优电池间距对于顺排布置为35mm,对于叉排布置为36mm。  相似文献   
10.
This paper proposes a parameter adjustable dynamic mass and energy balance simulation model for an industrial alkaline water electrolyzer plant that enables cost and energy efficiency optimization by means of system dimensioning and control. Thus, the simulation model is based on mathematical models and white box coding, and it uses a practicable number of fixed parameters. Zero-dimensional energy and mass balances of each unit operation of a 3 MW, and 16 bar plant process were solved in MATLAB functions connected via a Simulink environment. Verification of the model was accomplished using an analogous industrial plant of the same power and pressure range having the same operational systems design. The electrochemical, mass flow and thermal behavior of the simulation and the industrial plant were compared to ascertain the accuracy of the model and to enable modification and detailed representation of real case scenarios so that the model is suitable for use in future plant optimization studies. The thermal model dynamically predicted the real case with 98.7 % accuracy. Shunt currents were the main contributor to relative low Faraday efficiency of 86 % at nominal load and steady-state operation and heat loss to ambient from stack was only 2.6 % of the total power loss.  相似文献   
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