【正文】 nary, or OED for short. The idea for this dictionary came from an important meeting in Britain in 1857. Twentytwo years later, Oxford University asked James Murray to be the editor of its new dictionary. Murray had never been to college. At the age of fourteen, he left his village school in Scotland and taught himself while working in a bank. Later he became a great teacher. After Oxford gave him the job, Murray had a place built in the garden behind his house to do his work. Part of it was one meter underground. In winter it felt like a barn, he had to wear a heavy coat and put his feet in a box to keep warm. Every morning, Murray got out of bed at five o’clock and worked several hours before breakfast. Often he would work by the candle light into the evening. Murray hoped to finish the new dictionary in ten years. But after five years, he was still adding words for the letter A! then others went to work with Murray, including his two daughters. He worked on the dictionary until he was very old. Fortyfour years later, in1928, other editors finished it. It included more than 15,000 pages in twelve books. And you thought your dictionary was big!t know the best way of getting to places, she insisted that she organize the trip properly. Now, I know that the proper way is always her way. I kept asking her, When are we leaving and when are we ing back? I asked her whether she had looked at a map yet. Of course, she hadn39。 Several months before our trip,Wang Wei and I went to the library. We found a large atlas with good maps that showed details of world geography. From the atlas we could see that the Mekong River begins in a glacier on a Tibetan mountain. At first the river is small and the water is clear and cold. Then it begins to move quickly. It bees rapids as it passes through deep valleys, travelling across western Yunnan Province. Sometimes the river bees a waterfall and enters wide valleys. We were both surprised to learn that half of the river is in China. After it leaves China and the high altitude,the Mekong bees wide，brown and warm. As it enters Southeast Asia, its pace slows. It makes wide bends or meanders through low valleys to the plains where rice grows. At last, the river delta enters the South China Sea. We will reach Dali in Yunnan Province soon, where our cousins Dao Wei and Yu Hang will join us. We can hardly wait to see them!The next morning our group slept late. We were very tired from the long bike ride the day before. Cycling in the hills had been our couins had the chance to make jokes about Wangwei and me. Perhaps,they said,they were the strong ones!We had lunch at a nice outdoor cafe,then rode out of the city. Strange things were happening in the countriside of northest there days the water in the village wells rose and fell, rose and noticed that the well walls had deep cracks in them. A smelly gas came out of the cracks. In the farmeryards,the chickens and even the pigs were too nervous to ran out of the fields looking for places to jumped out of their bowls and about 3:00am on July 28,1976,some people saw bright lights in the sound of the planes could be heard outside the city,who thought little of these events,were asleep as usual that night.,表3:雙壁波紋管?空壁纏繞管?水泥管改良于價(jià)格比較(單位:元)規(guī)格雙壁波紋管(S1系列)空壁纏繞管(S1系列)水泥管重量kg/m價(jià)格施工費(fèi)用綜合費(fèi)用重量kg/m價(jià)格施工費(fèi)用綜合費(fèi)用重量kg/m價(jià)格施工費(fèi)用綜合費(fèi)用225452570406675107182300703010045100801202004001104015011143602031831161602765001316555220752671391803196001924072312263381004384003002005007002532095415303901345245504122506628003242011053040600168768650485300785表4:雙壁波紋管?空壁纏繞管?水泥管性能比較(以800mm為例)雙壁波紋管(S1系列)空壁纏繞管(S1系列)水泥管產(chǎn)品類別柔性管柔性管剛性管使用壽命50年以上50年以上20年左右每米價(jià)格420元600元485元施工費(fèi)用110元/m168元/m300元/m工程綜合造價(jià)530元/m768元/m785元/m結(jié)構(gòu)受外壓變形,但不易損壞受外壓變形,但不損壞受外壓及鋪設(shè)不平均能破損施工費(fèi)用重量輕?鏈接迅速?方便,搬運(yùn)輕便,重量較重?連接不太方便,重量最重(200kg/m),連接不方便?不可靠?施工耗力?耗材,連接方式承插?哈夫塊聯(lián)接熱縮膜?熱熔鏈接凹凸企口結(jié)合用水泥理化性能而沖擊?耐腐蝕?不漏水?耐寒性高?耐磨性強(qiáng)?壽命長而沖擊?耐腐蝕?不漏水?耐寒性高?耐磨性強(qiáng)?壽命長重量重?耐沖擊低?受壓已損壞?漏水?耐化學(xué)性差產(chǎn)品特點(diǎn)1?重量輕,成本低,具有很強(qiáng)的市場(chǎng)競(jìng)爭(zhēng)力?同中空壁纏繞管?纏繞成型式肋管相比,在相同管徑,相同環(huán)剛度下,單米重量最輕,可節(jié)省材料40~70%?2?連接方便?可靠,可采用彈性密封圈承插聯(lián)接(排水?排污?通風(fēng)等用途),也可采用密封圈外加哈夫塊連接(供水等用途)?3?HDPE雙壁波紋管具有優(yōu)異的耐低溫性,可在60℃~60℃下施工?4?制品的整體強(qiáng)度高,具有較大的軸向拉伸強(qiáng)度,能承受較大的與軸向拉伸力和周向的環(huán)應(yīng)力?5?具有很強(qiáng)的土壤適應(yīng)性?由于HDPE的斷裂延伸率可達(dá)500%?所以對(duì)地基的不均勻沉降?土層變動(dòng)均具有很強(qiáng)的適應(yīng)性?6?流通性能優(yōu)越?內(nèi)壁光滑,流動(dòng)阻力小,相同管徑下,比水泥管的流量更大?7?具有很高的耐磨性和耐腐蝕性,使用壽命長達(dá)50年之久,而水泥管在正常條件下的壽命為20年左右?8?屬于綠色環(huán)保產(chǎn)品,由于HDPE可完全回收,故不對(duì)環(huán)境造成污染?產(chǎn)品用途1?可廣泛用用于市政建設(shè)的排水?排污等管道系統(tǒng)2?農(nóng)田?水利灌溉?輸水?排澇等水利工程?3?化工?礦山用于流體的輸送以及通風(fēng)管等用途?4?地下管線的保護(hù)套管和通信電纜套管等用途?5?工廠?污水處理廠以及其他公共場(chǎng)所的管道?四?管材聯(lián)接管材可通過使用密封插接,或彈性密封圈加哈夫外固件連接等形式連接: 彈性密封圈承插聯(lián)接:彈性密封圈加哈夫塊外