My School

My school is very big. There are many beautiful buildings in it, such as the teaching building, the sports hall and the experimental building （实验楼）. There are two playgrounds in our school. One is large, the other is small. Our favourite places are the playgrounds. We like playing games on them. They make us happy and relaxed （放松的）.     

A Boy and His Tree

This is a story of everyone. The tree is our parents （父母）. When we were young, we loved to play with Morn and Dad ... When we grow up （长大）, we leave （离开） them, and only （仅仅） come to them when we need some- thing or when we are in trouble （在困境中）. No matter what, parents will always （总是） be there and give everything they could to make you happy. You may think that the boy is cruel （残忍的） to the tree but that＇s how all of us are treating （对待） our parents.     

Temporal variation in modal properties of a base-isolated building during an earthquake

Temporal variation of dynamical modal properties of a base-isolated building is investigated using earthquake records in the building. A batch processing least-squares estimation method is applied to segment-wise time-series data. To construct an input-output system, an auto-regressive model with exogenous input （ARX） of second-order including a forgetting coefficient as a weighting coefficient is used for the estimation of modal parameters. The fundamental and second natural frequencies and the damping ratios of the fundamental and second natural modes of the base-isolated building are identified in the time domain. The identified results are consistent with the results obtained from the micro-tremor vibration data, forced-vibration test data and earthquake records in the present base-isolated building in the case of taking into account the amplitude-dependency of the iso- lators and viscous dampers. It is finally pointed out that several factors, e.g., amplitude dependency of the isolator and damper system and special characteristics of the series-type viscous damper system, may be related complicatedly with the temporal variation in modal properties of the above-mentioned system.     

单元知识中考链接

1.Before2008we will finish_____theOlympic park.(2005北京市)A.build B.builtC.building D.to build2.—Where can I find Jack?—He_____the post office.(2006武汉市)A.has been to B.had been toC.has gone to D.had gone to3.—Where’s Sam?—He_____for France.(2006泰州市)A.had left B.has leftC.leaves D.will leave4.This is a big class,and_____of the stu-dents are girls.(2005河北省)A.two third B.second threeC.two thirds D.two three5.Shanghai is larger than_____city inIndia.(2005黄冈市)A.any other…     

颜色预告心情

O ur clothes are a powerful tool that can make us feel better about ourselves. One way in which this works is by wearing different colors of clothes. Normally when we are sad, we will wear dark colored clothes. Oppositely, when we are happy, we often choose to wear brightly colored clothes. The rea- son for this is that our choice of color mir- rors how we are feeling. Those who don’t believe in the idea are often heard saying,“if only this truly worked”. Well in reply to those people, the…     

The Best Way to Stay healthy

Health is one of the most important things to our happy life. So every one is concerned about it. Many people seek to maintain their health. What is the proper way to maintain health? In my view, the best way is to live a regular life. Regular life is the key to health. Some people are used to rising late and staying up1 late. They damage their health by disturbing the biological2 function in the body. A regular life can keep us fit. We are better prepared to study and work if we know the proper way to maintain healthy. We can benefit from the regular life all the life if we keep it up.     

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…     

Numerical simulation and optimization design of the EGR cooler in vehicle

The EGR （exhaust gas recirculation） technique can greatly reduce the NOx emission of diesel engines, especially when an EGR cooler is employed. Numerical simulations are applied to study the flow field and temperature distributions inside the EGR cooler. Three different models of EGR cooler are investigated, among which model A is a traditional one, and models B and C are improved by adding a helical baffle in the cooling area. In models B and C the entry directions of cooling water are different, which mostly influences the flow resistance. The results show that the improved structures not only lengthen the flow path of the cooling water, but also enhance the heat exchange rate between the cool and hot media. In conclusion we suggest that the improved structures are more powerful than the traditional one.     

Numerical investigation on the drag reduction properties of a suction controlled high-rise building

To reduce the wind-induced drag and improve the wind-resistance performance of a high-rise building, steady suction control is introduced into the building structure. Based on validation of the numerical methods by experiment with suction control over the flow separation ofa 3D backward-facing step, the Reynolds stress equation model is used to investigate the drag reduction （DR） properties of a high-rise building whose side faces are controlled by all-height suction. Effects of the orifice geometrical parameters and suction flux parameters on the DR and the separation control are analyzed, and the detailed flow fields are shown to clarify the mechanism of suction control. The results indicate that suction control is very effective in reducing the wind loads on the high-rise building model, and only the dimensionless suction flux dominates. Lastly, the power consumed and the counterforce induced by suction are discussed, the suction models become the ＂zero-drag＂ model under certain suction angles.     

Let's Do Something for Our Mothers

Mother's Day is coming soon.As a child,I think we should do something useful for our mothers and make them happy. One of the ways to celebrate Mother's Day is to give our mothers a day off.Let them relax while the rest of the family are doing the housework.Firstly,we should send our mothers some flowers or special small presents and say "Happy Mother's Day" to them.Secondly,we should do some housework,such as washing the dishes,cleaning the room and washing the clothes.We can also tell some jokes to our mothers and tell them something interesting in our school.I think these things can make our mothers happy.Finally,we should cook delicious food for our mothers.It's important for the whole family to have dinner together,because it will make our mothers feel happy.     

Optimization of time-delayed feedback control of seismically excited building structures

An optimization method for time-delayed feedback control of partially observable linear building structures subjected to seismic excitation is proposed. A time-delayed control problem of partially observable linear building structure under horizontal ground acceleration excitation is formulated and converted into that of completely observable linear structure by using separation principle. The time-delayed control forces are approximately expressed in terms of control forces without time delay. The control system is then governed by Itoe stochastic differential equations for the conditional means of system states and then transformed into those for the conditional means of modal energies by using the stochastic averaging method for quasi-Hamiltonian systems. The control law is assumed to be modal velocity feedback control with time delay and the unknown control gains are determined by the modal performance indices. A three-storey building structure is taken as example to illustrate the proposal method and the numerical results are confirmed by using Monte Carlo simulation.     

This Isn''''t My Day!

Mr Brown and Mr White are neighbours. They work in the same office building. They both have their own cars, but don't usually drive to work because traffic is bad and it is difficult to find a parking space. This morning they went to work together in Mr Brown's car, but they couldn't find a parking space in front of their office build-     

阅读理解高分训练

（A）
Apparently, we are safe neither at home nor in the business office. We use water in both places, but the research shows that chemicals added to our local water supply to kill harmful bacteria can have unwanted side effects. These chemicals can cause potential harm through drinking and in seemingly harmless activities as cleaning one＇s house. They are released（set free） from water by daily actions like water running out of tap, spraying from garden pipes, or splashing in dishwashers and washing machines. As the water is moving, these chemicals are released into the air and then breathed in. Once inside our bodies, they start to affect our health.     

Why Birds Sing?

Have you ever wondered why birds sing? Maybe you thought that they were just happy. After all, you probably sing or whistle when you are happy. Some scientists believe that birds do sing some of the time just because they are happy. However, they sing most of the time for a very different reason. Their singing is actually a warning to other birds to stay out of their territory.D o you know whata “territory”is?A territory is an area that an an- im al,usually the m ale,claim s(声称)as its ow…     

0ur School

Our school is not very large but beautiful. We love our school. Entering our school, you＇ll first see a big flower bed. There are many kinds of colorful flowersin it. How beautiful they are! If you go along the school road, on the left you＇ll see two teachingbuildings and you＇ll hear that the teachers and students are having classes. On the right you’ll seean office building.     

高考阅读理解专练(英文)

ASometimes the real world can be a confusing place. It is not always fair or kind. And in the real world there are not always happy endings. That is why, every once in a while, we like to escape into the world of fantasy -a place where things always go our way and there is always a happy ending. We want to believe in fantastic creatures in imaginary lands. We want to believe in magic powers, good     

英语第二册听力练习

1 在本题中,你将听到9个简短的对话,在每个对话后还将听到一个有关对话的问题（问题同时写在试卷上》。对话只放一遍。你必须在寻音留出的空白时间内从所给的四个选择中找出最佳答案,并把答案写在括号内（1）Question:Where　do　you　think　the　dialogue　most　proba-bly takes place?（　） A.In a rstaurant. B.In a hcopital. C.In a police　office. D.In a library. 录音内容:A:May　I　borrow　these　reference　books?B:Of　course.But　you　must　return　them　back　before　Friday. （2）Question:What　is　the　relationship　of　the　two　speakers? （　）     

2007考点预测40题(英文)

1. ——When did you arrive? ——I arrived ____ the morning of April 18. A. in B. at C. on D. by 2. The grandfather was ____ to see his grandson playing ____. A. happy; happy B. happy; happily C. happily; happily D. happily; happy 3. The moon is ____ the s…     

Numerical Analysis of Structural Progressive Collapse to Blast Loads

After the progressive collapse of Ronan Point apartment in UK in 1968, intensive research effort had been spent on developing guidelines for design of new or strengthening the existing structures to prevent progressive collapse. However, only very few building design codes provide some rather general guidance, no detailed design requirement is given. Progressive collapse of the Alfred P. Murrah Federal building in Oklahoma City and the World Trade Centre （WTC） sparked again tremendous research interest on progressive collapse of structures. Recently, US Department of Defence （DoD） and US General Service Administration （GSA） issued guidelines for structure progressive collapse analysis. These two guidelines are most commonly used, but their accuracy is not known. This paper presents numerical analysis of progressive collapse of an example frame structure to blast loads. The DoD and GSA procedures are also used to analyse the same example structure. Numerical results are compared and discussed. The accuracy and the applicability of the two design guidelines are evaluated.