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A novel phase-shifted zero-voltage and zero-current switching PWM DC/DC full-bridge converter is presented in this thesis, which is based on the groundwork of summarization of the development of Power Electronics in recent years and lucubration in theoretical basis of modern high frequency soft switching power convert technique and analysis of operation principle, characteristic of the circuit and inherent drawbacks of the traditional phase-shifted zero-voltage switching PWM DC/DC full-bridge con...

本文在对近年来电力电子学科的发展高度综述和对现代高频软开关功率变换技术理论基础深入研究的基础上，对传统的移相控制ZVS PWM DC／DC全桥变换器的工作原理、电路特性、存在的缺点进行了分析，在此基础上提出了一种改进型的移相控制ZVZCS PWM DC／DC全桥变换器。

To overcome these drawbacks, the application of current mode tri-state modulation technology to the switching power amplifier for magnetic bearings is proposed, as well as its special advantages.

文中首先分析了电流纹波对磁轴承系统的影响，接着分析了电流两态调制技术本身的固有不足及电流三态调制技术在磁轴承开关功放应用中的优势。

Switching power amplifier of magnetic bearing worked in hard switching. To overcome drawbacks of large loss of switching and current harmonic distortion, a parallel resonant DC link soft-switching power amplifier was adopted in this paper.

为克服磁悬浮轴承开关功率放大器工作在硬开关状态时存在的开关损耗和电流纹波干扰严重的缺点，提出一种磁悬浮轴承并联谐振直流环节的软开关功率放大器电路。

The drawbacks of existing marginal distribution capacity costare analyzed.

分析了现有配电网边际容量成本的不足。

Advantages and drawbacks of these drives are summarized. Various modulation schemes suitable for megawatt converters are discussed.

本文还论述了适用于大功率变流器的各种脉宽调制方式，并用计算机模拟和实验结果对一些重要的概念进行了论证。

But these traditional methods have certain drawbacks and limitations. To contain solution's reliability and stability the regularization is often adopted. The effectiveness of a regularization method depends strongly on the choice of a good regularization parameter.

在反问题的理论及数值计算方面，国内外的科学家做了大量的工作，提出了不少经典的数学和物理方法，但这些传统的方法都有其一定的缺陷或局限性。

The thesis work is to investigate the connection of [Ca2+]cyt and fertilization by avoiding drawbacks noted above, say, employing an ideal experimental plant, Torenia fournieri , with a naked embryo sac that protrudes from the micropyle.

因此，材料本身的结构限制和研究手段的限制使得植物双受精过程中胚囊内胞质游离钙的研究相比之下显得落后。

Aiming at the drawbacks of traditional BP neural network, such as converging slowly and tending to get into the local minimizer, the particle swarm algorithm is introduced into the training of neural networks.

此外针对传统的BP神经网络存在收敛速度慢以及容易陷入局部极小值的缺点，引入粒子群算法对神经网络的学习训练进行优化。

Owing to the drawbacks of analytical shimming, this paper puts forward the concept of passive numerical shimming for searching a method of compensating Bz'easily to a high level and with a low cost. Based on the magnetic field caused by a magnetic moment, the distribution of moments in a superconducting NMR imaging megnet can be determined through some pseudoinversion algorithm directly from Bz'. The moments are used to compensate Bz'.

无源数值匀场的出发点直接是不均匀磁场的磁场偏差B〓本身；无源数值匀场的基础为磁性材料的磁矩所产生的磁场；由已知B〓，通过某种逆运算，确定磁性材料的磁矩在主磁体中的分布，实施此分布，以磁性材料的磁矩所产生的磁场直接对B〓进行补偿——这便是本文提出的无源数值匀场的概念。

Due to the restrictions of the time, the traditional ecological moral philosophy is bound to have many drawbacks.

由于时代条件的限制，传统的生态伦理观在理论上必然存在着各种局限性。

But we don't care about Battlegrounds.

但我们并不在乎沙场中的显露。

Ah! don't mention it, the butcher's shop is a horror.

啊！不用提了。提到肉，真是糟透了。