无源网络接入B2B型MMC-HVDC的Lyapunov控制策略研究

模块化多电平变流器（MMC）用于高压直流输电（HVDC）系统中时,通常采用PI控制方法,但这种策略存在参数选取繁杂、动态性能较差的缺点。为了提高高压直流输电（HVDC）系统的动态性能、简化参数选取,提出背靠背（B2B）型模块化多电平变流器-高压直流输电（MMC-HVDC）系统的Lyapunov控制策略。首先,建立B2B型MMC-HVDC数学模型;然后,设计Lyapunov函数控制策略;其次,在控制部分加入环流抑制、移相载波调制等,以完整地实现系统功能;最后,在Matlab/Simulink平台上验证了Lyapunov控制策略具有参数选择容易、动态性能优良的特点。     

Global B.Sc. programme in renewable energy

A newly proposed Bachelor degree in renewable energy has been reported herein. The programme is aimed to be international. It consists of 140 credit hours and is an interdisciplinary programme run by the College of Science and Engineering. This programme has been already disseminated by the Islamic Scientific Educational and Cultural Organization (ISESCO), and Islamic Conference Organization (ICO), Morocco, which was designed by the present author for ISESCO.     

微波强化光催化处理罗丹明B染料废水

采用微波无极灯强化光催化(MWL/TiO_2)对罗丹明B模拟废水进行处理。初步研究催化剂TiO_2的用量、罗丹明B初始浓度、微波功率、溶解氧、pH、反应温度、外加氧化剂H_2O_2量等因素对罗丹明B降解效果的影响。实验结果表明:最佳催化剂TiO_2的投加量为4g/L;较低pH、高溶解氧浓度、高微波功率、外加氧化剂H_2O_2有利于罗丹明B的降解。与常规光催化相比,微波减弱pH、染料初始浓度对降解效率的影响,同时增强温度对降解效率的影响。     

发酵条件对发酵产氢细菌B49产氢的影响

采用间歇发酵实验，研究了葡萄糖浓度、接种量、温度、氮源、不同有机底物对发酵产氢产酸细菌新菌种IM9(AF481148 in EMBL)生物产氢的影响。结果表明，接种量影响IM9的产氢；IM9生长和产氢适宜温度均为35℃；IM9不能利用无机氮源，而有机氮是IM9生长、产氢的适宜氮源；葡萄糖是IM9发酵产氢的最适宜底物，当浓度为10g／L时，IM9的葡萄糖利用率为100％，氢气得率为1．69molH2／mol glucose；此外，IM9可利用小麦、大豆、玉米、土豆及糖蜜废水和啤酒废水产氢，其中利用糖蜜废水、啤酒废水产氢分别为137．9ml H2／g COD和49．9ml H2／g COD。     

国内外熔融高炉渣显热回收方法

分析了熔融高炉渣显热回收的必要性。因为熔渣的物理性质和高炉出渣不连续性,导致熔渣显热回收存在困难。介绍了滚筒法、搅拌法、风淬法、连铸法、离心粒化和反应热法显热回收工艺,并指出甲烷-二氧化碳重整法有很好的发展前途。     

Carbon Dioxide and Global Change: Earth in Transition. - S.B.IDSO

The authors have proposed a generalisation of the J-CHART method [1] for a polyvalent modular drying system obtained by multiple simulation of thermal performance of two standard configurations: without recycling the air leaving the dryer, with 50% recycling of the air leaving the dryer and mixing with the air leaving the collectors.

This method, named as “GJ-CHART” is based on the use of charts or polynomial correlations which allows to determine the fraction of monthly average heating load supplied by solar energy and the fraction of monthly average economized energy as function of the two dimensionless parameters. These parameters are related to the standard collector parameters, the data of monthly average radiation, temperature and the estimates of drying loads, which by consequence, allows for a more general use.

The GJ-CHART method was developed for drying 27 kg of apple slices placed in single layers on the trays of the modular dryer. The temperature and the drying air flow rate are 60^°C and 0.09 kg s^-1 respectively. The drying time of a drying operation depends on the configurations of the system used, varying between 12 to 13 hours. According to the assumptions we used and the ways in which the calculations are done, this design method can be generalized to provide a mean for quick estimation of the long-term performance of the partially solar heated polyvalent modular drying system.

Les auteurs proposent, à l'aide de multiples simulations, une généralisation méthode J-CHART [I] de dimensionnement d'un système de séchage modulaire polyvalent valable pour les deux configurations suivantes: sans recyclage de l'air sortant du sèchoir; avec recyclage partiel (50%) et mélange avec l'air sortant des insolateurs.

Cette méthode, baptisée “GJ-ABAQUE”, est basée sur I'utilisation d'abaques ou des relations polynomials qui sen déduisent: ceux-ci permettent de déterminer la couverture solaire mensuelle et la fraction de chaleur de séchage économisée mensuelle à partir de deux couples de paramètres adimensionnels qui les caractérisent respectivement. Ces derniers font intervenir notamment les paramètres standard des insolateurs, les conditions climatiques du site, la surface de captation et la chaleur totale de I'opération de séchage, ce qui permet, par conséquent, une utilisation assez générale.

Les travaux ont porté sur le séchage de 27 kg de rondelles de pommes déposées en couche unique sur des claies, dans un module de séchage, lorsque la temperature de I'air asséchant est de 60^°C et son débit de 0,09 kg s^-1. La durée d'une opération de séchage varie, suivant la configuration retenue, de 12 à 13 heures.     

DF8B型3001号机车的试验运行考核

对DF8B型3001号试验机车的燃油消耗和故障处所进行了统计分析,对显示的优越性和存在的问题进行了分析,提出了改进建议。     

高炉煤气独立燃烧节能技术的开发与应用

本文介绍了开发和应用高炉煤气独立燃烧节能技术的成功实践。采用了一系列新技术和新工艺后,使高炉煤气在轧钢加热炉内独立燃烧成为现实。不仅满足了轧钢车间生产需要,而且有效地利用了高炉煤气资源,节约了能源,提高了企业的经济效益,值得在本行业领域内推广。     

磁控溅射制备柔性衬底ZnO:Ga透明导电膜微结构及性能研究

室温条件下,采用磁控溅射法在有机柔性衬底聚酰亚胺(PI)表面制备出ZnO:Ga透明导电膜,XRD表明ZnO:Ga薄膜为六角纤锌矿结构的多晶薄膜。研究了溅射功率、氩气分压、溅射时间及衬底负偏压等溅射工艺参数对薄膜结构及光电性能的影响,得出最佳溅射参数分别为:功率100W,氩气分压0.1Pa,溅射时间60min,衬底负偏压40V。结果表明:磁控溅射制备的ZnO:Ga膜附着性良好,电阻率为9.4×10~(-4)Ω·cm,可见光透过率为78%。     

A tribute to D.B. Spalding and his contributions in science and engineering

This paper presents a summary of some of the scientific and engineering contributions of Prof. D.B. Spalding up to the present time. Starting from early work on combustion, and his unique work in mass transfer theory, Spalding’s unpublished “unified theory” is described briefly. Subsequent to this, developments in algorithms by the Imperial College group led to the birth of modern computational fluid dynamics, including the well-known SIMPLE algorithm. Developments in combustion, multi-phase flow and turbulence modelling are also described. Finally, a number of academic and industrial applications of computational fluid dynamics and heat transfer applications considered in subsequent years are mentioned.     

Application of ‘C.A.R.B. financial methodology’ analysis for alternative energy technologies into UK housing

Current energy trends in UK housing are reviewed and then assessed by introducing the ‘CARB financial analysis’ methodology. CARB is an acronym for ‘Carbon Abatement’, as it evaluates the potential carbon-dioxide reduction from different technologies; ‘Relative’, as all the technologies examined are dependant on various primary sources; and ‘Balance’, as the cost of surplus CO₂ is quantified. According to conventional financial analysis, most of the technologies examined have the potential to provide positive returns on the investments especially for those with an environmentally conscious agenda. Further reduction of up to 30% of most installed alternative energy systems cost is required to compete with an investment in, e.g., a UK pension scheme. Using the ‘CARB financial analysis’ the cost of reducing CO₂ has been quantified, and compared with the potential cost of climate change impact. Conventional installed solar technologies are not financially attractive both with a pay back period calculations and ‘CARB financial analysis’ under current market costs and governmental subsidy regimes. Heat recovery technologies could be sensible investments, both in financial and environmental terms under particular assumptions; especially if the investment budget is small. The use of cogeneration technologies provides a financial advantage in the attempt to minimise the cost of climate change impact, as pay back period of such investment could be less than 7 yr, and the cost of CO₂ saved could be two to seven times less than the global damage cost of carbon emissions.     

B0+B0-B0+B0轴式八轴机车的轴重转移分析

针对B0 B0-B0 B0轴式八轴机车不同的牵引方案,在定义了名义牵引高、过渡牵引高和等效牵引高的基础上,进行了轴重转移的计算分析.分析结果表明不管B0 B0-B0 B0轴式八轴机车的悬挂采用什么方案,机车的最佳牵引高总是接近轨面的,采用水平牵引装置很难达到最佳的黏着利用率.通过采用斜牵引杆结构,使机车的名义牵引高达到最佳牵引高,就能获得较高的黏着利用率.分析了斜牵引杆结构的名义牵引高和倾斜角对机车黏着利用率的影响,给B0 B0-B0 B0轴式八轴机车牵引机构的设计提供了理论依据.