乐观英文
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乐观英文范文第1篇
春天来了的英语作文【1】
Bitterly cold winter may once come, but now it has gone.
As my bike has been stolen, I have to run from one teaching building to another every day.
The bell declares the end of the last lesson and the beginning of a new journey. Tired as I am, at the sight of the bench, I go straight to it. As soon as I get seated, a world of fresh green immediately catches my eyes. Grass sprouts burst through the soil right in the place of the withered grass and turn the dull grey into fresh green. As I look up, I find those tall trees have also put on new clothes. Green, here and there, everywhere!Spring has come, I realize suddenly.
A breeze stirs, sending over breaths of fragrance. I trace it,surprised to find several lovely small white flowers dotted on a tree. Andthere are even some singing birds! I am so delighted with all these tiny lives that my fatigue vanishes all of a sudden.
春天来了的英语作文【2】
The sky shows its purest blue. The sun generously gives out its heat and light, shining evenly on the grass, on the trees,on the roofs of houses, on the people passing by, also on me,quietly and tenderly. There come a couple of young people,strolling leisurely. A group of students are sitting in a circle on the grass and discussing something heatedly. Some are reading English but in low voices afraid of breaking the peace of the campus. Others are lying on the lawn, having a nap, or just enjoying the sunshine as I am.
I feel I am free, free of thinking anything. In such a pleasing environment, doing anything is a great pleasure. I am fully indulged in this tranquility. If only time could stop!
I turn on the radio to enjoy some light music. Much to my disappointment, however, almost all the programs are about the war in Iraq. It is hard to believe that under the same blue sky,some people are suffering from bleeding and death of war while others are enjoying a happy life.
The sun is hidden by the clouds. After a few seconds, it shines brightly again.
Peaceful life seems to have gone, but it will come back one day, I am sure.
春天来了的英语作文【3】
What’s my favourite season? Let me tell you.My favourite season is spring. Spring is a lovely season, I think. There is a garden behind my house. In spring, the trees become green and the flowers give off fragrance(芳香). There are many butterflies and bees over the flowers. The butterflies are dancing and the bees are singing. Sometimes it rains. It usually rains quietly. The rain moistens(滋润) the trees and the flowers. I think they may say, “We’re very thirsty. The rain is very good. It can help us.” What a beautiful scene! Don’t you think so? And what about your favourite season,could you tell me?
乐观英文范文第2篇
——怎样做一名好学生
昨天，我观看了教育影片《为了孩子的明天》看后，感触特别深。
片中的刘刚，一位失足的16岁少年，开始只知道玩，他家住在市区，楼下尽是网吧、酒吧、歌舞厅，他每天只知道和他结交的那些不三不四的朋友去这些地方，连他父亲病危了也不理睬，照完不误，后来父亲去世了，母亲想让爱子学好，就迁到郊外去住，可刘刚还是老样子，网吧、酒吧、歌舞厅他天天都去，这还不够，他竟在课堂上刁难老师，老师问他头提及的圆锥和球体那个表面积大，而他却反问老师，同体积的男生和女生那个表面积大？在被老师，被派出所找了几次后，他的母亲桂芬，横下心来，辞去了工作，带着刘刚去了外地，从此，刘刚不再进网吧、酒吧、歌舞厅了，他知道家里没钱，便利用课余时间给别人当家教，他用挣得的钱为母亲买了一块蛋糕和一瓶红酒。
片中的母亲，开始以为只要让孩子吃好、穿好、玩好，孩子就会认真学习，所以什么事都宠着刘刚，再加上她工作很忙，没有时间管理刘刚。后来他觉得刘刚越来越不听话了，这才意识到这样下去是不行的，于是他学习“孟母三迁”的精神，用环境改的方法去改变刘刚，铁石心肠的刘刚终于被妈妈的爱所感动了，开始懂得学习，懂得替妈妈分担家庭责任了。而她自己，却因长时间患病做苦力活而死掉了，她临终前告诉刘刚，箱子底下有他爸爸生前留下的一百万元，一定要将这钱捐给希望工程……
乐观英文范文第3篇
The film tells the story of Helen Keller in her birth nineteen months time, because of illness, lost valuable listening and vision, so she became a deaf, dumb, and blind severe disabled. She doesn't like normal person study, the life, but Helen Keller in teacher Anne's help, her overcome her sick. Learn to use hand "talk", and mastered English, French, German, Latin, Greece five kinds of words, In her 24 years old, she graduate with excellent results in the famous Harvard University, it completely changed keller life.
See the film, gave me great comprehend: a deaf and dumb people can have made so great achievement, how surprising. If Helen Keller had succumbed to unfortunate fate, then it will become a poor YuWei "parasites". But she didn't head to fate, she with amazing perseverance, indomitable spirit, carvered wonderful life path.
Helen is a disabled, but her mind is key just and free, longing for the future, she himwith a single indomitable heart, created a miracle in human history, and with lovingkindnehands holding the world of the disabled. She is our pride, our example. Helen's life, are tough, will give to us great encouragement, so that those who idling people very regret. Helen unyielding life, not only gives us a lot of enlightenment: we these healthy people, not away your youth, we should treasure this beautiful life, cherish the happineof life. Don't wait for lost regret it, then already too late.
From Helen Keller body, I realized profoundly: a person will achieve, is not the condition quality, but in any struggle and progressive spirit. Had a target, just have the power, for this goal, will certainly encounter all sorts of difficulties, but as long as we march forward courageously, we will overcome all the difficulties and achieving brilliant achievements.
看着海伦·凯勒的电影,我不断飙升,我是海伦做出这么大的成就,这样的韧性,是海伦震惊他的精神颠簸的感动。
这部电影讲述了海伦·凯勒在她出生19个月的时候,因为生病,失去了宝贵的听力和视力,所以她成了聋子,哑巴,盲目的严重残疾。她不喜欢正常的人学习,生活,但海伦·凯勒的老师安妮的帮助下,她克服她生病。学习使用的手“交谈”,掌握了英语、法语、德语、拉丁、希腊五种文字,在她24岁,她以优异成绩毕业在著名的哈佛大学,它完全改变了凯勒的生活。
看电影,给了我很大的理解:一个又聋又哑的人能取得这么大的成就,令人惊讶。如果海伦·凯勒屈服于不幸的命运,那么它将成为一个可怜YuWei)“寄生虫”。但她没有头的命运,她以惊人的毅力,顽强的精神,走完了精彩的人生道路。
乐观英文范文第4篇
How are you?
I would like to tell you something that took place in my school yesterday. In the afternoon the school held a growing-up ceremony for our coming 18-year-old birthday. At the beginning we made an oath that as grown-ups we should have a sense of responsibility for our society. Next we expressed our thands to our parents who brought us up and to our teachers for their education. Then our teachers gave us cards with good wishes. Finally, we had wonderful performances. I learned a lot from the activity. I am sure the ceremony is very important for us. From then on we will know our responsibilities as grown-ups.
Yours,
乐观英文范文第5篇
【关键词】HB LED；前照灯；热管理
一、前照灯应用HB LED的优势
LED从上世纪50年代诞生到现在经历了过半个世纪的发展，适用于照明的高亮度白光LED于90年代中后期取得突破，十几年来拓展HB LED的应用一直都没有停止过。HB LED应用到汽车前照灯领域可获得的以下特性：
1.超长的使用寿命和优越的可靠性
HB LED的预期使用寿命约50000小时，远远超过现有卤钨灯、充气灯甚至氙灯的使用寿命，此外无灯丝、无空腔、结构坚固，不易受颠簸振动而影响正常工作，可靠性高；
2.优秀的电光转换效率
此前（2011年底）HB LED光效记录已经达到了230Lm/W，是氙灯的近三倍，更是卤钨灯、普通充气灯的十数倍以上。达到照度要求的情况下，降低功耗能有效降低发电机、蓄电池负荷及导线截面积，利于车辆向轻量化发展的需求；
3.极短的响应时间
普通灯泡由于灯丝热惰性，启动时间约250mS，氙灯需要建立启辉高压，启动时间则更长一些。LED的启动时间只在nS级，这一优势在极端情况下能为前、后车提供更多的反应车距；
二、汽车前照灯对光源的特别要求
1.前照灯的配光应使近光具有足够的照明和不产生眩目，远光具有良好的照明①。
前照灯包括远、近光灯，不论两灯制还是四灯制车辆，都要求光束有良好的汇聚和特定的分布，通过透镜、反光镜进行汇聚要求光源集中，以利于配光镜对车前照明进行配光，照度和配光同等重要。
2.前照灯应具有良好的散热性，防止光源热堆积，前照灯即使在低温凝冻的环境下仍能正常工作②。
汽车前照灯当前形势下仍然是汽车常规灯具中功率最大的，灯具高温失控将是很危险的火灾隐患。同时灯具高温也给其自身也带来工作稳定性和使用寿命的影响。此外，灯具热堆积将导致光源色温改变，使雨雾环境下光线穿透性能和反射光强度等产生变化，将影响驾驶安全。
三、前照灯应用HB LED必须解决的关键技术问题
根据前照灯对光源要求的以上分析，以及HB LED技术现状，笔者认为汽车前照灯应用HB LED在技术上主要存在以下两个关键问题。
1.开发小型大功率模块的需求非常迫切
就率先应用HB LED到前照灯的奥迪A8L W12车型而言，为达到照度要求，每侧使用了76个LED光源。以近光灯为例，单侧能耗达到了40W。且构件之复杂、组合之精密远远超出普通前照灯总成的结构和技术水平。
过多的LED数量给灯具设计提出了非常高的难度，要解决点光源分散、光束汇聚、水平配光、防眩目等结合难题。一种方案是将LED布置在反光镜抛物面内，以浪费各个器件部分光通量来确保汇聚后的整体光照度，再对光束进行配光。此方案导致成本高而节能优势削弱，成本浪费大。另一种方案是LED单体聚光，分组承担车前各区域的配光，例如对侧方人行道分配的光照由某几个LED实现。此方案的缺陷是个别LED失效将导致某配光分区不合格，严格意义上是整个前照灯不合格。当前奥迪A8L W12前照灯采用此方案（远、近光共用8个HB LED），各LED在应用时保留非常多的冗余量以策保险。此时器件性能的浪费也推高了制造成本。
因此，除了个别豪华车型撇除成本因素采用HB LED前照灯外，绝大多数厂家都在等待单颗功率更大的HB LED面世，以期应用更少量的LED元件降低设计难度和制造成本。
2.大功率HB LED的热管理难题
HB LED发光区别于灯丝发光和电弧发光，因为没有炽热部分将热量通过辐射耗散，工作时自身热能堆积，只能够通过传导的形式向外耗散，需要散热装置和预留散热路径。另外前照灯在寒冷气候中还要面临积雪和凝冻状况，传统灯具有灯泡的辐射热存在，一定程度上对抗了工作中积雪和凝冻。采用HB LED光源后，前照灯就有必要配备化霜装置，否则无法实现全天侯照明。同时，要解决光源自身的散热，且必须不受前照灯化霜热量的影响，因此，可靠控制LED的关键是热管理措施。
首先，结温波动的控制。结温波动直接影响LED的光效，汽车前照灯照度大小关系到低能见度环境的行车安全，且车辆行驶时，环境温度、湿度等因素变化频繁，灯具所处散热环境复杂，要稳定结温必须散热速度可控，且感温和控制模块必须灵敏度高、响应快；
其次，结温高低的控制。结温过高是影响LED工作寿命的最重要因素，就目前成本而言，HB LED前照灯总成是普通前照灯总成的好几倍。高造价要求控制模块有足够的可靠性，驱动电流必须结合散热速度调节；
再次，结温高低的选定。结温影响到LED的色温和显色指数，高色温时，人眼的敏感度高，但对车外人员易造成眩目，不符合交通安全法规要求；高色温还带来显色指数的下降，加速驾驶员的视觉疲劳。作为制造厂家必须确保不同批次的LED都工作在适当的色温和较好的显色性。所以要求控制模块具有结温参数设定的功能。
当前奥迪A8L W12车型的LED前照灯通过在灯组尾端安装冷却风扇来解决散热问题，结构复杂和可靠性不足，且结温高低和散热工况波动控制不够理想。
控制芯片方面，当前安森美半导体开发了NCV78663，通过PWM控制平均电流，其高能效、高可靠性、集成控制、LED自检及动态控制系统参数等功能被业界普遍认可，至于大功率HB LED应用于汽车前照灯要求对工作结温和散热参数的精确控制却并没有被纳入，也就是说仍处于开环控制系统，一旦出现严苛的工作环境，热失控的现象将马上显现。
四、总结
基于汽车前照灯的特别工况和特殊的性能要求，HB LED并没有如大众所想象的顺利应用到汽车前照灯技术中。但是HB LED的优点是显著的，未来汽车前照灯使用HB LED光源将是必然的趋势。更高功率的单颗HB LED将简化前照灯结构，闭环热管理的控制系统将充分发挥其高光效、长寿命的优点，使系统更加可靠。彼时，才是全面普及LED前照灯的时代。
注释：
①引用自《GB 4599-1994汽车前照灯配光性能》
②引用自《GB 25991-2010汽车用LED前照灯》2011年5月第一版
参考文献
[1]GB 4599-1994E汽车前照灯配光性能.
[2]GB 4599-2007汽车用灯丝灯泡前照灯.
[3]GB 4785-2007汽车及挂车外部照明和光信号装置的安装规定.
