聚会胡淼家
•2006年10月5日 • 3条评论亲历上赛场的经典一役
•2006年10月1日 • 2条评论
写在上海站前
•2006年09月30日 • 3条评论走上正轨
•2006年09月29日 • 5条评论as a freshman~~
•2006年09月22日 • 一条评论交大的第一周
•2006年09月15日 • 2条评论转眼7年
•2006年08月30日 • 2条评论xnwy西南位育记事
•2006年08月25日 • 4条评论前两天回学校,发觉xnwy又按惯例开始小规模装修了,这次把花样搞在了操场上。其实在西南位育这几年还是有许多挺有趣的地方的——
*操场:初中毕业时,跑道终于变成了塑胶的,可惜好象普遍反映对成绩没什么大帮助嘛;今年暑假,发觉篮球场被涂成了红的和绿的,真是丑陋……
*教学楼:也是鲜红的颜色,貌似没什么特别,实际有隐患哦!从初三以后我们就再也没有在篮球场晨跑过了,转向跑道去,原因就因为教学楼质量。据说只要全校学生在操场跑,6楼会感到抖的!由于物理老师领衔这种说法,当然无话可说咯。高一时候拆掉了原来的实验楼,造了个活动楼,但至今也没开始用,听说是未通过验收,汗啊。
*屋顶花园:进高中后也改造过了,本来绿色的塑料毯现在铺了淡蓝的地砖,住在那里附近的一同学从高楼看到后跟我说:“我们学校造了个露天游泳池哎……”哈哈。奇特的是在这光溜溜的地面上打羽毛球倒也从来不打滑!
*食堂:新建的学生灶头间在网球场那里,进是没进过但体育课经过时,总能闻到股刺鼻的油烟味,所以每每跑过那段路总是冲得特别快~~教工食堂当然一般莫入的,但那里门口贴着一周菜单,有个同学高二时候每天清早进教室就向我们通报中午吃什么,提前作好心理准备吧。
*校服:春夏季的大概算是经典,咖啡色的,但是被周围的一些学校不同程度地盗版了,非常郁闷。冬季那是最有性格的了,简单来说就是“青蛙+茄子=7年”,不止依次指着远处的环卫工人说“那是我们学校的嘛……”
*铃声:高一开始,上下课由传统的铃声变成了音乐,上、下课不同,而且半学期更换。其实是个不错的改变,但大概有时是文艺部的人挑选不当,上课中途“匡匡”巨响,吓死人的事情(后来下课铃都改成比较温柔的了~),持续时间很长差不多要2、3分钟,倒也有好处哦:老师要拖堂也没辙了,那分贝绝对盖过嗓音。
*杂音:在XNWY上课免不了会受到某些声音的干扰,若是朝南,就是六院的救护车“滴嘟滴嘟”;朝北么,每天早上9:00,从对面幼稚园就传来樱桃小丸子的音乐,老可爱的喏。但都习惯了,也没发觉影响很大,反而觉得老亲切的!
*政教主任:刚进初中是被我们称为“孙二娘”的,雷厉风行,据我们语文老师说开教工大会老喜欢说“xxx老师遭到表扬”妈呀……到了初二,换成了JQ,她的讲话风格真是有意思,既想威严一点,但什么事儿让她一说就喷饭了。大冬天她千叮万嘱“同学们放学别忘了关电灯和电风扇……”苦口婆心的。
*班会:例行的公事,学校安排也无非是思想教育、事迹报告、颁奖意识、法制讲座,大多比较无聊。若是自行安排,要么是讲40分钟大道理,然后理书包(实际上这个早已完成了);还有要什么小组讨论之类的,有段时间只要一开始讨论,我们的话题就是“秀豆魔岛士”哈哈;简单的么,就是“大家自修吧”,欧耶!
*眼操:其实没什么好说的,这是大家最不愿意干的。记得赵君有个绝招,就是音乐一响立马拿扫帚扫地或者擦黑板或者搓抹布,屡试不爽,真让他混了一阵,还被表扬,唉阴险的。
*电视:能看除学校电台的机会不多,主要是中午休息时间(幸好每次都是我喜欢的体育台呵呵),12点吃饭时电视一开的画面往往是NBA第四节,正是高潮部分,端着个饭碗到第一排,有的人索性爬到讲台上去了!另外就只有体育课碰上下雨天了,永远是《灌篮高手》,奇怪的是总是那几集:就三井打架的那段嘛!
……
其实还有很多,尽管都不是什么上台面的大事儿,也不是xnwy的光辉形象,却是最贴近这7年生活的一些细节和插曲,有点八卦,还是挺怀念的。
F1赛车的空气动力学(前一篇的DIY译文)
•2006年08月24日 • 发表评论全英文的东西真是看得累死了,这还只是第一篇,算了,反正2个月没接触英文了,就当自我训练吧。呵呵,这次的内容纯属自行翻译,也不知道准确否,?我的日志已经成了F1专版了~~
一部现代的F1赛车与一架飞机有许多共通之处,就如它与一辆普通汽车的相通处一样多。空气动力学已成这项运动成功的关键所在,因此各个车队每年要在这个环节的研发上花费几千万美圆。
空气动力学设计师有两个基本的任务:一是如何获得下压力,来帮助是赛车轮胎抓住赛道并提升转向力;二是把因气流和启动引起的使赛车减慢的阻力减到最小。
许多车队从60年代后期开始了对类似现行的定风翼的测试。赛车定风翼的工作原理与飞机定风翼几乎一样,只是倒置而已。空气以不同的流速通过两侧的定风翼(必须流经不同的外形、距离),由此产生了压力的差异,被称为伯努力原理。由于这压力需要平衡,定风翼就要向低压的方向移动。飞机利用两翼产生上升力,而赛车则依靠其产生下压力。因为有了空气动力学下压力,一部现代的F1赛车能产生3.5g的侧向转向力(相当于其自身重量的3.5倍)。这意味着,理论上来说高速行驶时,它们能够上下颠倒地被驾驶。
早期对可移动定风翼等的试验导致了一些重大事故的发生,因此在1970赛季出台规定,限制了定风翼的大小和位置。经过长久以来的发展,那些规则很大程度上沿用至今。
在70年代中期,"地面效应"下压力被发现。莲花车队的工程师发现,若在赛车底部装上帮助它"黏"住地面的巨型风扇,整部车就能向机翼一般工作。这种设想最终的实例是布拉汉姆车队(Brabham)的BT468,由Gordon M urray设计,其中实际上用了一架风扇从赛车底部的裙脚部分排出空气,以便产生巨大的下压力。但这项技术在一场分站比赛后因受到其他车队的技术挑战而退出舞台。并且后来改动的规则限制了对"地面效应"的利用–先是对容纳低压区域的裙脚的禁令,之后是对"stepped floor"(?)的要求。
尽管完整的风洞和强大的计算机被大多数车队的空气动力学部门利用,F1的基本原理依然适用:力求最大的下压力和最小的阻碍力。根据各条赛道的不同下压力需求,前后定风翼被调整到不同的角度安装。
每辆F1赛车的外表,从悬挂系统到车手头盔的形状,都将空气动力学的作用考虑在内。从车身被分流扰乱的空气,产生了气流,气流则导致了减慢赛车的阻力。观察一下近年来的赛车你会发现,在减少阻力上所花费的精力并不比在提升下压力方面的少–从防止旋涡形成而安装在定风翼上的汽车底盘,到后部低置的扩散板。这些都帮助再次平衡从底部通过赛车的高速气流产生的压力,否则便会在尾部有类似于低压"气球"阻碍赛车。除了以上这些,设计师也要注意不能让赛车太容易打滑,同时又必须保证充足的空气流动,帮助散发赛车引擎产生的巨大热量。
近来的大多F1车队都试图效仿法拉利车队的"窄腰"设计,将赛车尾部制造得尽量窄而低。这样可以减小阻力并把尾翼得到的空气量提高到最大。
2005年修订起用的规则迫使空气动力学专家们必须有更创新的理念。在一个减速的条款中,FIA(国际汽联)通过提高前鼻翼,把尾翼前移,更改后部扩散板等措施使赛车失去一大部分下压力。但设计师们运用大量复杂而新颖的手段很快弥补了这些损失,例如麦克拉伦(McLaren)的MP4-20喇叭形的winglets(?)。
understanding F1—Aerodynamics
•2006年08月23日 • 发表评论The aerodynamic designer has two primary concerns: the creation of downforce, to help push the car’s tyres onto the track and improve cornering forces; and minimising the drag that gets caused by turbulence and acts to slow the car down.
Several teams started to experiment with the now familiar wings in the late 1960s. Race car wings operate on exactly the same principle as aircraft wings, only in reverse. Air flows at different speeds over the two sides of the wing (by having to travel different distances over its contours) and this creates a difference in pressure, a physical rule known as Bernoulli’s Principle. As this pressure tries to balance, the wing tries to move in the direction of the low pressure. Planes use their wings to create lift, race cars use theirs to create downforce. A modern Formula One car is capable of developing 3.5 g lateral cornering force (three and a half times its own weight) thanks to aerodynamic downforce. That means that, theoretically, at high speeds they could drive upside down.
Early experiments with movable wings and high mountings led to some spectacular accidents, and for the 1970 season regulations were introduced to limit the size and location of wings. Evolved over time, those rules still hold largely true today.
By the mid 1970s ‘ground effect’ downforce had been discovered. Lotus engineers found out that the entire car could be made to act like a wing by the creation of a giant wing on its underside which would help to suck it to the road. The ultimate example of this thinking was the Brabham BT46B, designed by Gordon Murray, which actually used a cooling fan to extract air from the skirted area under the car, creating enormous downforce. After technical challenges from other teams it was withdrawn after a single race. And rule changes followed to limit the benefits of ‘ground effects’ – firstly a ban on the skirts used to contain the low pressure area, later a requirement for a ‘stepped floor’.
Despite the full-sized wind tunnels and vast computing power used by the aerodynamic departments of most teams, the fundamental principles of Formula One aerodynamics still apply: to create the maximum amount of downforce for the minimal amount of drag. The primary wings mounted front and rear are fitted with different profiles depending on the downforce requirements of a particular track. Tight, slow circuits like Monaco require very aggressive wing profiles – you will see that cars run two separate ‘blades’ of ‘elements’ on the rear wings (two is the maximum permitted). In contrast, high-speed circuits like Monza see the cars stripped of as much wing as possible, to reduce drag and increase speed on the long straights.
Every single surface of a modern Formula One car, from the shape of the suspension links to that of the driver’s helmet – has its aerodynamic effects considered. Disrupted air, where the flow ‘separates’ from the body, creates turbulence which creates drag – which slows the car down. Look at a recent car and you will see that almost as much effort has been spent reducing drag as increasing downforce – from the vertical end-plates fitted to wings to prevent vortices forming to the diffuser plates mounted low at the back, which help to re-equalise pressure of the faster-flowing air that has passed under the car and would otherwise create a low-pressure ‘balloon’ dragging at the back. Despite this, designers can’t make their cars too ‘slippery’, as a good supply of airflow has to be ensured to help dissipate the vast amounts of heat produced by a modern Formula One engine.
Recently most Formula One teams have been trying to emulate Ferrari’s ‘narrow waist’ design, where the rear of the car is made as narrow and low as possible. This reduces drag and maximises the amount of air available to the rear wing. The ‘barge boards’ increasingly fitted to the sides of cars also help to shape the flow of the air and minimise the amount of turbulence.
Revised regulations introduced in 2005 forced the aerodynamicists to be even more ingenious. In a bid to cut speeds, the FIA robbed the cars of a chunk of downforce by raising the front wing, bringing the rear wing forward and modifying the rear diffuser profile. The designers quickly clawed back much of the loss, with a variety of intricate and novel solutions such as the ‘horn’ winglets on the McLaren MP4-20.
