Research on a simulated 60 kW PEMFC cogeneration system for domestic application

INTRODUCTION Distributed cogeneration technology is a hot topic in electrical and energy industries (Ferguson and Ugursal, 2004). China’s need to limit the power usage in some places to meet the peak power demand in summer of recent years stimulated and supported increasing research on distributed generation tech- nologies. Fuel cells, as renewable energy sources, are considered one of the most promising sources of distributed electrical power. Operational fuel cell systems have perform…     

高二英语单元检测

hoolardenfnglishU nit5T he B ritish IslesⅠ.单项填空1.The culture and custom s of A m erica are very m uch like of Eng-land.A.that B.w hat C.w hich D.those2.Com m unist spirit consists whole-hearted devotion to public in-terests.A.in B.w ith C.of D.on3.—I don tthink Jack can sing w ell.—But you are shy,he is courageous.A.where B.w hat C.though D.if4.A ctually,he is a new-com er unknown us all.A.for B.as C.by D.to5.Charles Babbage is generally considered the first com puter.A.to in…     

Failure Process and Energy Transmission for Single-Layer Reticulated Domes Under Impact Loads

No failure, moderate failure, severe failure, and slight failure are the four failure modes generalized observed in the dynamic response of the single-layer reticulated dome under vertical impact load on apex. TE (the time that the end of impact force) and TF (the time that members are broken) are two key times in the failure process. Characteristics of dynamic responses at the two key times are shown in order to make the failure mechanism clear. Then three steps of energy transfer are summarized, i.e. energy applying, energy loss and energy transfer, energy consump-tion. Based on the three steps, energy transfer process for the failure reticulated dome under once impact is introduced. Energy transmissibility and local loss ratio are put forward firstly to obtain EL F(the energy left in the main reticulated dome) from the initial kinetic energy of impactor. More-over, the distribution of failure modes is decided by EL F which leads to the maximum dynamic re-sponse of the reticulated dome, but not by the initial impact kinetic energy of impactor.     

Helical Configurations of Elastic Rods in the Presence of Interfacial Traction

The Kirchhoff thin elastic rod models are always the important basis to explore the configuration mechanism of the flexible structures in both the macroscopic and microscopic scale. As a continuum model of DNA, a thin elastic rod subjected to interfacial interactions is used to investigate the helical equilibrium configuration of DNA in salt solution. In this paper, the Kirchhoff’s equations in the presence of interfacial traction and the free energy density functions of different configurations are studied. The transition formula of the free energy between B-DNA and ZDNA is obtained, and the results show that the free energy of the transition is mainly determined by the salt concentration, which agrees well with the experimental data.     

Unit 6 Good manners学习指导

一、词汇过关1.m anner【用法】用作名词,意为“a way of doingsom ething or the way in which a thing is doneor happens做事的方法;事情发生的方式”。例如:W hy are you talking in such a strangem anner?你为什么用这种奇怪的方式谈话?m anner还可表示“a w ay of acting;bearingor behavior态度;举止”。例如:H is m anner was slightly rude,but youm ustn’t m ind.他的态度有点粗鲁,但是你千万别介意。m anner的复数形式可表示“the sociallycorrect way of acting礼貌;礼节”。例如:It’s bad m anners to talk w ith a fullm…     

Common Words from Proper Names

In the present English vocabulary there is a group of common wordscoined from the different proper names.The use of a proper names to conveya general idea is termed antonomasia.By the means of antonomasia thenames originally used to refer to specific persons.places and somethingelse are now used as common words which carry their own fresh meanings.Inthis short article it is discussed in detail that from what sources thesecommon words are produced.     

Fat or Fit

Doctors in Britain are warning of an obesity time bomb(肥胖定时炸弹), when the children who are already overweight grow up. So, what should we do? Exercise more? Eat less? Or both? The government feels it has to take responsibility for this expanding problem.The cheerful M r Pickw ick, the hero of the novel by C harles D ick- ens,is seen in illustrations as som eone who is plum p——and happy.In the 18th century paintings beauty is equated w ith rounded bodies and soft curves. B ut nowaday…     

颜色文化——橙色(英文)

Flam boyantand E nergetic 醒目、充满活力 O range is vibrant.It’s a com bination of red and yellow so it shares som e com m on attributes w ith those colors.Itdenotes energy,w arm th,and the sun.B utorange has a bitless intensity or aggression than red, c     

Optimization of Selecting Air Conditioning Cold/Heat Sources with Grey Relation Analysis

Selection of air conditioning (AC) cold/heat sources generally concerns about certain aspects and cannot reveal the whole profile of the problems. Grey relation analysis (GRA) is a data processing method to categorize the correlation extent of compared sequences and a certain reference sequence in a system with uncertain information. It is applied to evaluating and selecting AC cold/heat sources from four main aspects, which are technology, economy, reliability, and operation and management. Case study shows that the result for selecting AC cold/heat sources with the GRA method can be more reasonable and convincible. Thus it offers a new approach for designers in heating, ventilating and air conditioning field to compare and evaluate different AC cold/heat sources.     

高一(上)重点词汇专练(Units1～12)(英文)

1.W e adm ire those are loyal their nation.A.who;w ith B.w ho;toC.whom;to D.that;to2.I don t care in his com pany.A.to see B.to be seenC.seeing D.being seen3.M ike often argues angrily his friend sm all things,w hichsom etim es m akes us very unhappy.ool den lish A .with;for B .w ith;about C.to;for D .to;about 4.—W ho, ,is the bestfootball player in China today? —I think it is Sun Jihai A .as a result B .in your opinion C.m ore or less D .in all 5.She w as scared the yard because she…     

Science Letters:On the critical radius in generalized Ostwald ripening

INTRODUCTION A polydisperse precipitate produced by nuclea-tion in a metastable supersaturated solution is far from thermodynamic equilibrium, i.e. a state of minimal free energy. A decrease of free energy is accom-plished by a coarsening of the precipitate which es-sentially reduces the surface free energy with respect to the surrounding solution. The process is called Ostwald ripening and is a direct consequence of the Kelvin effect (Adamson and Gast, 1997), that is the higher solubi…     

Pleasure Island

No matterwho you are or whatyou are interested in, H awaiiis theplace to go.Ithas som ething to offereveryone.Sitting in the Pacific Ocean, the strings ofislands have som e ofthem ostbeautifulbeaches on earth.W ith pure white sands lined with green cliffs, the sea is greatforsurfing in winterand swim m ing and diving in sum m er.The m ild clim ate,green trees and charm ing flowers offer beauty and harm ony (和谐) totourists allthe yearround.Its hard for visitors to choose which ofthe m any i…     

On Connotation of Color Terms in Chinese and English

Because different peoples have different environments,customs,ways of thinking,religious beliefs,regimes,literature and arts and ways of living,there is no surprise that colors are described diversely in different countries.And they show the partic ular personalities of each nation.And language is not only the carrier of culture,but also it is an important part of culture.In oth er words,culture includes and influences language.People could know culture through language.So only when people combine culture with language can they succeed in communicating with each other.There are various color terms in both Chinese and English,and which have similar or different associations,indications and connotations.So to have a good mastery of the differenc es and similarities of these words and their associations,indications and cultural connotations is a prerequisite for a better under standing of the different cultures of eastern and western countries,which will make the communication easier.This paper will ex plain the four colors:red,white,black and yellow.     

A PAC Based Current Feedforward Control for Three-Phase PWM Voltage-Type Converter

This paper presents a novel current feedforward control strategy for a three-phase pulse-width modulation (PWM) DC voltage-type converter based on phase and amplitude control (PAC). With right-angle triangle relation of phasors and principle of conservation of energy, a phasor adjustment method and the relevant low-frequency mathematical model of the system are analyzed in detail, both in rectification and regeneration modes for the converter, are discussed. For improving the traditional PAC dynamic performance, variable load current is detected indirectly by the change of the DC voltage, which is fed to the control system as an additional control variable to generate modulation index and phase angle. Also, the algorithm is derived and the system principle is introduced. Experimental results from a 3 kw laboratory device are included to demonstrate the effectiveness of the proposed control strategy.     

单一弹性常数近似下向错线对二维液晶自由能的贡献

In light of the Ф-mapping method,the contribution of disclination linges to the free energy density of 2-dimensional liquid crystals is studied in the single-elastic constant approximation.It is pointed out that ,compared with the previous theory ,the free energy density can be divided into two parts.One is the usual distorted energy density of director field around the disclination lines.The other is the free endrgy density of the disclination lines themselves which is centralized at the disclination lines and topoligically quantized in a unit of 1/2kπ .The topological quantum numbers are determined by the Hopf indices and Brouwer degrees of the director field at the disclination lines,i.e.,the disclination strength.From the method of Lagrangian multipliers,the equilibrium equation and the molecular field of 2-dimensional liquid crystals are also obtained.It is shown that the physical meaning of the Lagrangian multiplier is just the distorted energy density.     

An Energy Absorber with Force Modificator

Thin-walled tubes are extensively applied in engineering, especially in vehicle structures to resist axial or traversal impact loads, for their excellent energy absorbing capacity. However, in the axial deformation mode, the force history has an extremely high peak force which may bring not only fatal injury to occupants but also damage to structures, cargo and environment. Aiming to develop energy absorbers with impact-force modificator, square metal tube with force modificator is investigated which can monitor the force-deformation history of the tube. A small device is designed to serve as an impact-force modificator, which introduces desired imperfections to the square tube just before the impact happens between the impactor and the tube, so as to reduce the peak force. Prototypes with various governing parameters were manufactured and tested both quasi-statically and dynamically to study the effects of these parameters on the characteristics of energy absorption. The results show that the force modificator can achieve the desired reduction of the peak force well whilst remaining the specific energy absorption capacity of the original square tube. With future improvements, it could be applied to vehicles or roadside safety hardware to mitigate the consequences produced by traffic accidents.     

A Letter Is a Treasure in my Life

With the development of high technology, we are living a modern life, which is featured with a high tempo and a high pressure as well.People have different choices of getting in touch and com m unicating with each other.C hatting on line and sending e-m ails are becom ing m ore and m ore popular. ButI prefer to w rite letters to m y friends and relatives. Letters help m e a lot when I have a difficult tim e in m y life. Lastyear , I attended a key school , which was far away from m y hom eto…     

初中英语易错题专练(一)(英文)

1.This is the departm ent_______ M rSm ith hasserved for30 years.A . in which B.what C .forwhich D .w hom2.Idon蒺tlike _______.A .young m en sm oke B .young m en sm okingC.young m en蒺ssm oke D .thatyoung m en sm oke3.W as itLondon _______ M arx m ade the base forhis revolutionary work?A .w here B.in which C.which D .that4.In the end they had to _____ to youropinion.A .give up B .give away C.give off D .give in5.So eagerly _____ to konw the resultofthe com petition thatshe wouldn蒺tgo …     

Reading

I like to do different kinds ofthings,but I like reading best.R eading is very good.It isgood for im proving our w riting.Itcan w iden our eyes.It can m ake you be a bright person.“Tim e is m oney”.Absolutely,I read hard,I try to catch everym inute to do som e reading.R eading m akes m y life so beautiful.M ost of girls likeshopping,but I prefer to read books rather than go shopping.Shopping can’t w iden our know ledge,but reading can.I like being friend w ith books,and books are m y be…     

音相近,意相远——同音异义词

在英语学习中,学生经常会碰到一些发音相同、意思相异的单词。对这些单词,学生往往感到无所适从,不能分辨它们的意义。在这里笔者对常见的一些同音异义词作一个归纳和总结,希望对学生的单词学习和记忆有所帮助。1.There are m any holes in the w hole w all of theclassroom.2.I want to see the sea w ith m y m other during thesum mervacation.3.Itdepends on w hether the w eatheris fine ornot.4.They try their best to write the right words for therite.5.Ihave one of m y eyes exam ined this m orning.6.Ourteam w illwin…