Asymptotic rejection of sinusoidal disturbances based voltage balance control in back‐to‐back power converters

This paper addresses the imbalance problem of the dc‐link capacitor voltages in the three‐level diode‐clamped back‐to‐back power converter. In order to cope with it, a mathematical analysis of the capacitor voltage difference dynamics, based on a continuous model of the converter, is first carried out. It leads to an approximated model that contains explicitly several sinusoidal functions of time. In view of this result, the voltage imbalance phenomenon can be addressed as an output regulation problem, considering the sinusoidal functions of time as exogenous disturbances. Thus, a novel approach to deal with the mentioned problem in the back‐to‐back converter is presented. Then, the particular features of the disturbances are used to design several controllers. They all follow an asymptotic disturbance rejection approach. In this way, the estimates of the disturbances are used to apply a control law that cancels them while regulating the capacitor voltage balance as well. Finally, the performance of the proposed control laws is evaluated, presenting the simulation results obtained when the different controllers are implemented. Copyright © 2013 John Wiley & Sons, Ltd.     

PTPRD and DCC Are Novel BACE1 Substrates Differentially Expressed in Alzheimer’s Disease: A Data Mining and Bioinformatics Study

The β-site Amyloid precursor protein Cleaving Enzyme 1 (BACE1) is an extensively studied therapeutic target for Alzheimer’s disease (AD), owing to its role in the production of neurotoxic amyloid beta (Aβ) peptides. However, despite numerous BACE1 inhibitors entering clinical trials, none have successfully improved AD pathogenesis, despite effectively lowering Aβ concentrations. This can, in part, be attributed to an incomplete understanding of BACE1, including its physiological functions and substrate specificity. We propose that BACE1 has additional important physiological functions, mediated through substrates still to be identified. Thus, to address this, we computationally analysed a list of 533 BACE1 dependent proteins, identified from the literature, for potential BACE1 substrates, and compared them against proteins differentially expressed in AD. We identified 15 novel BACE1 substrates that were specifically altered in AD. To confirm our analysis, we validated Protein tyrosine phosphatase receptor type D (PTPRD) and Netrin receptor DCC (DCC) using Western blotting. These findings shed light on the BACE1 inhibitor failings and could enable the design of substrate-specific inhibitors to target alternative BACE1 substrates. Furthermore, it gives us a greater understanding of the roles of BACE1 and its dysfunction in AD.     

有效支持WLAN的接入算法研究及其性能分析

对IEEE 802.11协议的DCF功能进行了研究,在分析原有的DCC算法的基础上,对其进行了改进,提出了一种增强型的DCC算法——EDCC算法．改进后的EDCC算法采用一维自回归滑动平均模型ARMA(α)平滑处理的方法,克服了原有DCC算法对时隙利用率估计方差较大的缺点,提高了DCC算法的性能,保持了原有算法的简单性、完全分布性、无开销性及其自适应性．仿真结果表明EDCC算法不但能够提高网络的通过率而且能够有效降低网络的业务负荷,实现降低节点能源消耗的目的,性能优于原有的DCC算法．     

催化裂解工艺技术及其工业应用

催化裂解（DCC）是从催化裂化衍生的生产丙烯的新技术。石蜡基原料的丙烯质量产率可以达到23％,而中间基原料的丙烯产率约为17％。催化裂解汽油再循环到催化裂解装置可以增产3．5％的丙烯,但汽油产率有所下降。75－150℃催化裂解汽油的BTX体积含量达到57．6％,其中甲苯和二甲苯分别为21．9％和30．3％。催化裂解催化剂是一个含改性五元环中孔沸石的固体酸催化剂,汽油一次产物在孔沸石内进行二次裂化转化为轻烯烃。已开发出一系列的催化裂解催化剂以适应不同目的需要,如最大量丙烯生产、最大量异构烯烃生产,最大原料掺渣油量等。自1990年以来国内外共有7套催化裂解工业装置正在运转,其中3套是由催化裂化装置改造成的,而另外4套包括TPI公司750kt/a工业装置是新建的。目前TPI公司的催化裂解装置正满负荷运转,加工掺40％常压渣油原料。尽管现在加工的原料比设计原料重,但丙烯产率仍可达到设计值。本文介绍一些典型工业装置的运转情况。     

Effect of non-condensable gas on the performance of steam-water ejector in a trigeneration system for hydrogen production: An experimental and numerical study

An ejector containing phase changing gas-liquid flow process acts as a popular and decisive device in multiple industrial applications, including the hydrogen production, electricity production, fuel cells, refrigeration, petroleum industry and desalination systems. However, non-condensable gas is inevitable for the usual operation of phase-changing gas-liquid ejector in the trigeneration or electrolyzer system for hydrogen production, and rarely research is concerned with this issue. In the present study, the effect of non-condensable gas contained in the condensable gas on the characteristics of gas-centered water ejector is presented, with steam, water and air acting as the gas, liquid and non-condensable gas, respectively. Experimentally, the flow rate of steam is controlled to be 1.45 g/s with an absolute pressure of 120 kPa, the air flow rate varies from 0 to 0.14 g/s, resulting in a non-condensable gas concentration ranging from 0 to 9%, and the resulted water flow rate at 100 kPa and 282.15 K changes from 34.7 to 37.3 g/s. Combined with the numerical methods, the performance of ejector expressed in ejected water flow rate was found to increase firstly with a small amount of non-condensable gas, and decrease when the non-condensable gas reaches a certain amount. In addition, the distributions of multiple local flow parameters including pressure, condensation rate and gas volume fraction, velocity and temperature inside the ejector were shown for different non-condensable concentration, by which the mechanism for the change of ejector performance under varying non-condensable concentration was demonstrated. These findings are initiative and insightful for the ejector design optimization in the trigeneration system for hydrogen production and the proposed numerical models can be utilized in analysis and design of steam ejector with non-condensable gas involved.     

超深度加氢精制催化剂在裂解柴油加氢装置的应用

为适应柴油质量升级的要求,中海油东方石化有限责任公司（简称东方石化）0.3 Mt/a DCC工艺裂解柴油（简称裂解柴油）加氢装置于2017年4月更换催化剂为标准催化剂公司的生产超低硫柴油的加氢精制DC、DN系列催化剂及OptiTrap系列保护剂。工业应用结果表明,裂解柴油加氢装置所采用的标准公司加氢精制组合催化剂在脱硫、脱氮及芳烃饱和等方面均具有优异的加氢活性及稳定性,能够生产硫质量分数小于10 μg/g的柴油产品,解决了东方石化柴油质量升级的难题。     

富氧燃煤锅炉烟气再循环方式选择与水分平衡计算

在不同的二次烟气再循环方式下,以300 MW富氧燃烧锅炉机组为例,对分别采用直接接触式冷却器（DCC）进行烟气脱水和湿式脱硫（FGD）与DCC串联进行烟气脱硫及脱水的富氧燃烧系统详细计算并比较了烟气中水蒸气体积分数的变化,并计算和比较了各种布置方式下的风机功耗.结果表明：单独采用DCC脱水情况下,锅炉烟气水蒸气体积分数比空气燃烧方式下高10%-15%;二次循环烟气脱水时,锅炉烟气中的水蒸气含量比空气燃烧方式下高约3%;FGD与DCC串联布置时的锅炉流通烟气水蒸气含量略高于采用单独DCC时二次循环烟气脱水的水蒸气含量;电厂循环水温度为30℃时,DCC出口烟气理论水蒸气体积分数为4.28%;单独采用DCC脱水的干烟气循环方式的风机总电耗最小.     

基于MSTP传输网的DCN网络优化的研究

随着电力企业基于同步数字体系的多业务传送平台(MSTP)光传输网络规模的不断扩大,设备数量迅速增加,在一个光传输网的管理域内可能出现数百个网元节点,使数据通信网络(DCN)的规模过大,出现告警性能数据不能及时上报、网元频繁脱管、网管操作速度变慢等现象。文章根据云南电力通信光传输网的组网结构和DCN网络现状,合理规划该光传输网的DCN网络,提出了DCN网络的子网划分方法,解决了网管信息丢失、网元脱管等问题,增强了光传输网的运行可靠性和有效性。     

α-（5-氟尿嘧啶-1-基甲基甲酰基）氨基-2-甲基戊酸的合成

采用碳二亚胺法以5-氟尿嘧啶-1-基乙酸、二环已基碳二酰亚胺和L-亮氨酸为原料,1-羟基苯并三氮唑为辅助试剂,通过液相偶联法合成了-种新型的α-（5-氟尿嘧啶-1-基甲基甲酰基）氨基-2-甲基戊酸化合物。通过红外光谱、元素分析和核磁共振氢谱等确证了其结构。     

DCC汽油加氢生产芳烃抽提原料技术（NHTDC）的开发及应用

通过对DCC汽油性质的深入分析，中国石化石油化工科学研究院开发了DCC汽油加氢生产芳烃抽提原料技术（NHTDC）。长期生产运行数据表明，以硫质量分数为50～350 μg/g、氮质量分数为19～69 μg/g、溴值为20～71 gBr2/(100 g)的DCC汽油为原料，可以生产出硫、氮质量分数小于1 μg/g、溴值小于0.5 gBr2/(100 g)的满足芳烃抽提装置进料要求的产品，并且在DCC汽油硫含量、氮含量和溴值变化较大的情况下，产品质量基本保持稳定，装置可长周期稳定运转，可以满足芳烃抽提装置对进料的要求。