基于有限时间一致性的微网分布式二次控制

针对孤岛运行模式下的微电网一次控制采用下垂控制易受到线路阻抗特性、微网拓扑结构等因素的干扰,造成频率与电压的波动以及功率难以比例分配的问题,提出一种基于有限时间一致性的微电网分布式二次控制策略来实现频率与电压无静差调节以及功率按比例分配的控制目标。所提控制策略结合多智能体理论来构建微电网的分布式控制结构,各分布式电源仅需通过通信网络与相邻节点进行各类电气信息交换,消除一次控制中频率与电压的偏差。同时引入自适应虚拟阻抗使系统输出阻抗呈感性来削弱线路阻抗不匹配的影响,从而实现无功功率的按比例分配。理论分析和仿真结果验证所提控制策略的有效性。     

船舶制造精度管理及过程控制技术探讨

造船精度管理技术直接影响造船质量及效率,对船舶行业发展具有极其重要的意义.通过介绍补偿量计算分配的理论基础及方法、船舶建造的过程控制和精度标准的制定等方面的内容,概括出造船精度管理的内容及实施的步骤.总结了建造工艺热应力变形的机理等造船精度管理难点问题的研究情况,提出了船舶建造动态控制这一先进的造船过程控制技术,并从尺...     

多约束容错性WSN中继节点布局算法的研究

针对目前中继节点布局算法所忽视的中继节点通信容量以及网络整体能耗等问题,本文将通信路径不可逆以及中继节点通信容量等约束条件引入现有中继节点布局模型,并提出了基于最小通信网络距离因子的布局算法评价新标准.解决方法上,采用了基于枚举法与贪婪寻优算法的中继节点布局算法,实现了WSN中继节点的多约束容错性布局.仿真实验表明,本...     

一种用于LDO稳压器的共享预稳压电路

提出了一种用于LDO稳压器的共享预稳压电路.该共享预稳压电路中包含一个电源抑制减法电路以提高基准源的电源抑制,应用电流负反馈结构以降低基准源的温度系数和电源抑制随工艺阈值电压变化的敏感度,还可以降低LDO稳压器的输出噪声.仿真结果表明在阈值电压发生士20％变化的情况下,基准源的温度系数变化只有0.11×10-6/℃,电...     

基于0.18μm CMOS工艺2.5Gb/s宽动态范围光接收机前端放大电路设计

基于0.18μm CMOS工艺设计了适用于2.5Gb/s传输速率的宽动态范围光接收机前端放大电路（包括前置放大器和限幅放大器）.前置放大器采用了RGC输入级的跨阻放大器,并且应用了消直流电路和自动增益控制电路扩展输入动态范围.限幅放大器采用了按比例缩小尺寸、并联峰化和带有有源负反馈的Cherry-Hooper放大器等方法扩展带宽.仿真结果表明：前端放大电路的中频增益为116dBΩ,-3dB带宽为2.13GHz,输入信号动态范围为40dB（0.01～1mA）.     

Synergistically optimizing thermoelectric performance of ZnO ceramics by interfacial band alignment and self-doping defects

ZnO is a promising thermoelectric ceramic material due to non-toxicity and abundance in resources. However, its thermoelectric performance is limited by the intrinsic low carrier concentration and high thermal conductivity. In this work, we synthesized the (1 ? x)ZnO/xZnS (x = 0–0.05) powders by a two-step solution method followed by microwave sintering in an oxygen-deficient environment at 1000 ℃, and then produced the self-doped ZnO ceramics with ZnO/ZnS interfaces. The electrical and thermal properties was investigated from room temperature to 900 K. The ZnO/ZnS interface and self-doping significantly increased the electrical properties of ZnO ceramics, the electrical conductivity (σ) and Seebeck coefficient (α) increased simultaneously with temperature for (1 ? x)ZnO/xZnS (x > 0), and the highest power factor (PF, 3675 µW·m^?1·K^?2) was obtained from 0.98ZnO/0.02ZnS at 900 K. At the same time, the ZnO/ZnS interfaces and self-doped defects greatly reduced the lattice thermal conductivity. Finally, the highest ZT value of 0.94 has been reached in 0.95ZnO/0.05ZnS at 900 K.     

含L-精氨酸和抗氧化物质组方对小鼠免疫功能影响

该文探讨一种含L-精氨酸和抗氧化物质(山楂提取物、知母提取物和虾青素)组方对小鼠免疫功能的影响。将SPF级雄性ICR小鼠随机分为四组,分别为对照组和受试物低、中和高剂量组(0.133、0.267和0.800 g/kg·BW)。连续灌胃30 d后,测定小鼠主要免疫器官脏器系数、细胞免疫功能指标、体液免疫功能指标、非特异性免疫功能指标。结果显示,该组方(中、高剂量)能显著提高淋巴细胞增殖能力和NK细胞活性,低、中、高剂量均能显著提高小鼠巨噬细胞吞噬鸡红细胞百分率及吞噬指数。在该实验条件下,组方具有增强小鼠免疫的功能。     

对流方程的交替分组显示方法

提出了求解对流方程初边值问题绝对稳定的二阶精度交替分组显示方法.模型问题的数值结果表明,本方法忧于陈景良和陆金甫的分组显示方法.     

Ceramics/metals joining under the influence of electric field: A review

Joining ceramics with ceramics and/or metals is of immense importance to widen the application horizons of ceramics and metals. Solid-state joining is restrained by the high joining temperature and long joining time, both of which can be reduced by liquid-state joining. However, the operating temperature of different ceramic-based components is low because of the low melting temperature of the filler. In order to rapidly join ceramic-based materials at low temperatures, various joining techniques utilizing the effect of an electric field (E-field) have been developed. These methods are generally classified into four categories, i.e., spark plasma sintering joining, low E-field assisted joining, anodic bonding and flash joining, according to the value of applied E-field and the types of materials to be joined, resulting in different joining mechanisms and joint performances. These methods are reviewed from the viewpoint of material types that can be joined and mechanisms.