无刷直流电动机模糊控制系统仿真研究

无刷直流电动机是一种非线性的控制系统,传统的控制方法很难实现对它的精确控制。模糊控制不依赖被控对象精确的数学模型,可根据操作者或专家的经验,实现对系统的控制。本文设计模糊控制器和自适应模糊PID控制器,并进行了仿真研究,仿真结果表明提高了系统的控制精度。     

多模式定位系统接收机中的分数频率综合器

针对单一的全球定位系统中接收性能易受环境影响的问题,提出了一个应用于3个定位系统、7种模式的多模式定位接收机中的分数频率综合器.通过改进的电流泵电流校正方法和提高谐振回路Q值等各种降低相位噪声的方法,达到了每种模式工作的稳定性和低相位噪声性能;以改进的多模分频器和3阶MASH1-1-1Σ-Δ调制器实现了7个频点的精确输出和各模式的快速锁定;在多模分频器中使用简单的电路将分频比的范围从64~79扩展到64~95.仿真结果表明,在每种模式下带内相位噪声(相对于载波的相噪声)均小于-90 dB,带外频偏1 MHz处相位噪声均小于-119 dB,杂散抑制(相对载波)均大于56.4 dB,各个模式锁定时间均小于18μs,1.8 V电源条件下的功耗为15.12 mW.     

一类本原有向图的m-competition指数及广义scrambling指数

根据图论、数论和集合的相关知识,对本原图中任一点经过k长途径所到达点的集合进行分析,结合广义competition指数和广义scrambling指数的定义,研究了一类特殊本原有向图(含有2个s-1圈和s个s圈)。得到了这一类本原有向图的m-competition指数以及广义scrambling指数。     

Different Kinetics of Puerarin in Plasma of Normal and Depressed Rats After Oral Administration of Chinese Medicine TZ18

The objective of this study is to quantify the puerarin in rat plasma following oral administration of TZ18 and compare the pharmacokinetics characteristics of puerarin in normal rats with that in depression model rats. A high performance liquid chromatography method was used to quantify the puerarin due to its good selectivity and linearity (coefficient correlation, r2 = 0.9991) within the tested range (0.028-0.889 μg·mL-1). Intra- and inter-day precision coefficients of variation and accuracy bias were acceptable (Maximum coeffi- cient of variation was 5.74% for intra-day and 3.09% for inter-day) over the entire range. The recoveries were found to be 98.3%, 101.4%, and 103.4% for concentrations of 0.028, 0.222, and 0.444 μg·mL-1, re- spectively. The concentration-time curves for both normal rats and depression model rats were fit to a two- compartment model with the first order absorption. The results show significant differences in the main phar- macokinetic parameters of peak time, peak concentration, and the area under the concentration-time curve between the two kinds of rats.     

电弧炉炼钢多氯萘的排放及影响因素

多氯萘(PCNs)是新持久性有机污染物(POPs),于2015年被列入《斯德哥尔摩公约》.电弧炉炼钢是PCNs的排放源之一,然而目前对电弧炉炼钢厂PCNs排放的研究相对较少,且当前关于电弧炉炼钢中PCNs等POPs的研究也主要集中于冶炼过程,而忽略了原料预热过程中PCNs的排放.电弧炉炼钢行业近年来使用高温废气在废钢入...     

浅析资本形成对经济发展的作用与对策

资本形成是经济发展的重要方面。中国要想保持经济的持续内生发展,了解资本形成对经济发展的作用与对策是非常必要和重要的。文章首先从概念上对资本形和经济发展进行了界定,然后从经济发展史的角度对资本形成对经济发展的作用进行了阐述.最后,结合中国实际,提出了相关对策。     

Long-Term Exposure to High Corticosterone Levels Inducing a Decrease of Adenylate Kinase 1 Activity

Corticosterone, a principal glucocorticoid synthesized in the rodent adrenal cortex, can be cumulatively toxic to hippocampal neurons, the cause of which is not known. The present study determined whether the cytosol adenylate kinase (AK) system was involved in the neuronal damage induced by long-term exposure to high corticosterone levels. We investigated the effects of long-term exposure to high corticosterone levels on AK1 activity, AK1 mRNA expression, and energy levels in cultured hippocampal neurons. The results show that long-term exposure to high corticosterone levels induces a reduction of the cultured hippocampal neuron viability, significantly reduces energy levels, and causes a time-dependant reduction of the AK1 activity. These findings indicate that changes in the AK system might be the mechanism underlying neuronal damage induced by long-term exposure to high corticosterone levels.