基于AVR单片机的智能充电器的设计与实现

介绍了以AVR单片机为核心智能充电器的控制原理,讨论了充电器的硬件结构和软件设计思想.该充电器对充电过程进行全面管理,描述了充电检测的关键技术,实现了智能充电.并对充电电源、电压进行自动检测调整,充电后自动转为恒压浮充状态,使充电过程按理想的充电曲线进行,达到既保护电池、又能使电池充满的最佳效果等要求.这种全新的智能充电方式,有效地解决了普通充电器将蓄电池"充坏"的技术难题,大幅度提高了蓄电池的实际循环寿命,是电动自动车、电动汽车的理想产品.     

高速公路TD-LTE系统覆盖性能测试及分析

如何保证移动终端在高速移动状态下的网络性能,是通信网络建设的难点。本文对TD-LTE高速专项覆盖网络进行了测试,并通过理论分析对比与TD-SCDMA系统的覆盖性能差异,最终给出高速道路网络建设的站间距意见。本文为后期TD-LTE网络设计和建设提供了一定的依据。     

一种二极管桥式跟踪保持电路设计

设计了一种基于二极管桥的两级全差分跟踪保持电路,两级模块由独立的时钟控制,可以各自工作在跟踪模式。芯片采用1μm GaAs HBT工艺实现,芯片大小为1.8mm×2mm,功耗2.75W。经测试,电路可以工作在1GS/s采样速率下,单端输入峰峰值250mV信号时采样带宽超过7GHz;单端输入峰峰值250mV,DC-2GHz信号时,电路具有8bit有效位。     

高速信息网络技术及其进展

主要论述了基于ATM和帧中继的高速广域网络技术,千兆位快速以太网、FDDI和ATM－LAN等高速局域网络技术;讨论和分析了高速网络及其相关技术的应用及发展趋势。     

非平衡桥式电路中互易定理的应用

本文介绍了将互易定理应用于非平衡桥式电路中的某支路上物理量的求解,以及对非平衡桥式电路等效电阻的求解,为等效电阻的求解提供了另一种思路。通过实例的讲解,学生可更好地掌握互易定理的使用以及等效电阻的求解,既丰富了教学内容,又开阔了学生的视野。     

Coexistence of multiple bifurcation modes in memristive diode-bridge-based canonical Chua’s circuit

Based on a memristive diode bridge cascaded with series resistor and inductor filter, a modified memristive canonical Chua’s circuit is presented in this paper. With the modelling of the memristive circuit, a normalised system model is built. Stability analyses of the equilibrium points are performed and bifurcation behaviours are investigated by numerical simulations and hardware experiments. Most extraordinary in the memristive circuit is that within a parameter region, coexisting phenomenon of multiple bifurcation modes is emerged under six sets of different initial values, resulting in the coexistence of four sets of topologically different and disconnected attractors. These coexisting attractors are easily captured by repeatedly switching on and off the circuit power supplies, which well verify the numerical simulations.     

A thyristor- and thermistor-based inrush current limiter for DC-link start-up

Large inrush currents can be harmful to equipment subjected to it and can also disturb other devices through voltage dips. Traditional ways of dealing with large inrush currents include the usage of parasitic elements in the supply, negative temperature coefficient (NTC) resistances and start-up relays. These solutions have several disadvantages among which are a non-negligible standby consumption, using a relay or a compromise between inrush current and load losses using an NTC. This paper proposes a solution which solves these disadvantages. The proposed circuit uses a semi-controlled bridge rectifier requiring a very low standby power consumption and is capable of withstanding grid interruptions. Moreover, it is designed to power on only when the load is not too heavy. This is accomplished by the use of positive temperature coefficient thermistors. The presented solution can be used for DC-link start-up circuits in applications with a power range from several watts up to a few kilowatts and it is particularly suitable for on-board battery chargers designed for electrical vehicles.     

剪刀式桥梁展桥机构铰点位置多目标优化设计

阐述一种新型剪刀式桥梁展桥机构的工作原理。针对方案样机在架设初始状态时展桥机构驱动油缸小腔受力过大、引起间断液压油溢流问题,利用Denavit-Hatenberg齐次变换矩阵建立展桥机构的运动学和静力学模型。根据展桥机构驱动油缸闭锁力与驱动力不同的特点,提出确定剪刀式桥梁展桥机构关键铰点位置的多目标优化计算方法。对剪刀式桥梁方案样机展桥机构的关键铰点位置进行优化设计,利用机械系统动力学分析ADAMS软件进一步验证了优化计算模型。研究结果表明：优化后展桥油缸的最大拉力降幅达59.5%,展桥油缸的受力分布趋于合理;所提出的展桥机构计算模型正确;优化方法具有收敛速度快、稳定性好等特点;展桥机构优化计算结果为方案样机改进提供了依据。     

LS-SVM在桥梁结构健康预测评估中的研究

桥梁的结构变形包含的桥梁结构内涵信息丰富,具有非线性、时序性和样本容量小的特点.利用支持向量机,以杭州湾大桥实测变形数据为研究对象,提出了基于LS-SVM的桥梁结构变形预测模型,通过实验证明了运用其对桥梁结构健康状况进行评估的可行性和有效性,并且通过实验结果对比显示了最小二乘支持向量机在变形预测中的优势.     

针对容性压电负载的桥式功率放大电路的设计

功率放大电路负责驱动容性压电负载,是整个压电执行器的关键部件.根据某驱动电源中的功率放大电路作为设计对象,通过采用桥式电路结构,从而提高了整体性能;通过研究放大器的共模输入电压范围,从而设定了非对称电源;通过分析波形,从而设定了电压增益;通过采用过压保护和限制电流,增强了电路的安全性;通过计算热工,设置了散热方式;通过使用方波测试法,测定了电路的稳定性.实验结果显示,该方法能实现双极性输出,以至于性能上的提高胜过了成本和复杂性的增加.