改进型全桥逆变电路的研究

提出一种改进型全桥逆变电路结构,在全桥电路两桥臂之间跨接一个储能电感,采用单周期的控制策略,配合极性控制,实现输出交流电压幅值可调,能够适应宽的电压范围,且结构简单。详细分析了改进型逆变电路的工作原理,并推导了系统单周期控制下的小信号模型,通过对系统进行闭环设计,实现了输出电压的精确调节。仿真和实验结果证明了此方案的有效性。     

Direct and two-step methods for closed-loop identification: a comparison of asymptotic and finite data set performance

The asymptotic and finite data behavior of some closed-loop identification methods are investigated. It is shown that, when the output power is limited, closed-loop identification can generally identify models with smaller variance than open-loop identification. Several variations on some two-step identification methods are compared with the direct identification method. High order FIR models are used as process models to avoid bias issues arising from inadequate model structures for the processes. Comparisons are, therefore, made based on the variance of the identified process models both for asymptotic situations and for finite data sets. Process model bias resulting from improper selection of the noise and sensitivity function models is also investigated. In this context, the results support the use of direct identification methods on closed-loop data.     

PWM开关功率变换器闭环系统平衡点稳定性分析

基于等效小参量法所得的稳态周期解,本文将特征方程分析法推广应用于开关功率变换器闭环系统平衡点稳定性分析当中。文中着重阐述了其基本原理。分析实例表明,结合相轨迹曲线,此方法简单而直观,具有明显的实用价值。     

一种速率自调节可用带宽测量算法

可用带宽是网络路由、网络服务质量、流量工程等方面的一个关键参数。目前很多研究方法都基于PGM模型和PRM模型,但这两种方法大都假设背景流量速率为固定比特流,不适用于低带宽的测试。提出一种端值自调节可用带宽测量算法,该算法充分考虑了低链路带宽的情况。通过对排队延时的处理、探测分组列速率端值自适应调节,实现了端到端可用带宽快速准确的测量。实验结果表明,该算法具有良好的测量效果,尤其在低带宽条件下较其它同类算法提高了测量准确性,加快了测量速度并减小了对网络的影响。     

一种闭环自激式驱动的硅微机械电场传感器

该文提出了一种闭环自激式驱动的微型电场传感器方案。利用自动增益控制的原理实现闭环自激驱动,使得微传感器能够始终工作在谐振状态,且振动幅度保持稳定。用matlab-simulink工具对系统进行了仿真,结果表明,当传感器的谐振频率发生0.5%的漂移时,系统可以重新捕捉并锁定到新的谐振频率,和开环驱动方案相比,传感器振幅的衰减度从30%降低到0.1%之内,灵敏度从缩减50%改进到缩减0.1%之内。     

基于双环控制功率逆变桥系统的 Multisim仿真与分析

本文主要介绍了当前最新的EDA软件Multisim2001的强大功能及其特点,该软件为电力电子电路的计算机仿真提供了一种新方法。采用该软件对功率逆变桥双闭环系统进行了仿真与分析,获得了控制参数与系统性能之间的关系,提供了一个通用闭环系统的Multisim模型。     

MIMO的反馈信道研究

该文提出了在闭环MIMO容量研究中引入了率失真理论的研究方法,推导出了反馈信道速率和闭环MIMO容量之间的数学关系。通过理论分析和仿真结果,得出了有关反馈信道速率与信噪比,天线数,闭环MIMO容量之间变化关系的四个重要结论。为实际的闭环MIMO系统设计提供了折衷反馈信道开销和闭环MIMO容量的依据,对系统设计有重要的指导意义.     

半开式自调节重力热管应用研究

本文提出了一种新型半开式自调节重力热管,解决了开式重力热管存在的密封液倒灌和液位失温问题。可广泛应用于电站锅炉排烟及高温工业废气的余热回收,具有较高的可靠性和显著的节能效果。     

Pricing and warranty decisions in a two-period closed-loop supply chain

For a two-period closed-loop supply chain (CLSC) consisting of a manufacturer and a retailer, Stackelberg game analyses are conducted to examine pricing and warranty decisions under two warranty models depending on who offers warranty for new and remanufactured products and the corresponding benchmark models with a warranty for new products only. Next, we identify the conditions under which warranty for remanufactured products is offered and investigate how this warranty affects the CLSC operations. Subsequently, comparative studies are carried out to examine equilibrium decisions, profitability and consumer surplus of the CLSC between the two warranty models. Analytical results show that offering warranty for remanufactured products does not affect new product pricing in period 2, but influences the pricing of new products in period 1 and remanufactured products in period 2, thereby enhancing remanufacturing, individual and channel profitability, and consumer surplus. Compared to the retailer warranty for remanufactured products, the manufacturer warranty can attain a more equitable profit distribution. If the warranty cost advantage of the manufacturer (retailer) is significant relative to that of the retailer (the manufacturer), the manufacturer (retailer) arises as a natural choice to offer warranty for remanufactured products as this decision enhances both profitability and consumer surplus.     

Ressourcenschonung und Kreislaufführung in der Prozessindustrie

Efficient use of material and energy flows increases the competitiveness of manufacturing companies and saves the environment at the same time. In order to significantly reduce the use of non-renewable materials and energy, a change from a linear to a closed-loop production process is necessary. In recent years, various closed-loop strategies have been developed, implemented or are in the process of being implemented. In this paper, a brief overview of approaches for a circular economy in the process industry is given.