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教你用纸折一个能旋转的解压六芒星,剪三根长二十八,宽两厘米的长方形纸条对折,两根纸条互相穿插在一起,像这样一直折到底, 就得到很多折痕。三根都进行处理,左边的纸条夹住中间的纸条,再穿过中间的 慢慢拉紧,三根都拉到底就会变成这样的。接着上面沿压,折痕向下折,左边向右边折,右边向上折,再从顶部穿过去,中间就变成一个立方体。 把上面的纸条向下折,折个三角形翻上去,向下折个角向上折,打开下面折角,再向上对折,横着插进缝隙里, 另外两个角一样折法翻到背面,同样的折法, 只是最后部分只能竖着插进缝隙里。剩余两边都折完之后,一个好玩又解压的流氓星就折好了。


哈喽,大家好,我是道士,请布艺只做有意思的折纸。最近呢,有一位道友给我留言问, a 四纸裁完正方形之后,剩下的一小块有没有什么用?因为大多数的折纸啊,都是用这个正方形,所以 说剩余的这个小长条攒了很多很多。所以呢,今天我们就来做这个镂空的转子花球,这个折比较大,并且很有弹性, 造型呢也比较有设计感,并且由于它是镂空的,我们可以把里面放一个发光的灯泡,做成一个小夜灯,或者是一个灯笼。这里呢,我拿一个手机的手电筒模拟一下,还是挺好看的吧,我们可以看一下棚顶上。 其实做这个折纸需要的纸张比例长宽笔是五比二,类似纸裁完正方形剩下的几小块呢,非常接近五比二, 所以说就可以直接拿来用。但是如果你之前没有攒那么多,需要怎样去裁这个五比二的纸呢?如果你手里有十五厘米的正方形纸,那么最简便的办法就是直接用尺子量先量出一个三厘米,直接把它裁掉,剩下的部分上下对折,直接把它裁开,这样就得到了两张五比二比例的纸。 但是如果你的正方形纸边长,不太容易被污整除,我们可以直接这样先沿对角线对折,压出折痕底边向着对角线折痕对折,底边再次向新折痕对折,这样我们在最左边的位置把它压出标记点打开最左 左边,这里就是五分之一点,我们过这个点把下面向上对折压平,把这部分裁掉好,剩下的呢,直接上下对折,和刚才一样把它拆开,这样呢也得到了两张五比二比例的纸,而且在你需要裁更多这种比例的纸的时候,直接拿出这个小长条,把它作为一个模板,直接裁掉这个 宽度就可以了。好,解决了纸的问题之后,下面我们开始正式来折,首先沿着短边方向上下对折,在两边轻轻压出折痕,注意不要整个都压平。我们把上下两边向着刚才这个标记点对折,然后沿着长边左右对折,把它打开,左边的部分向中线对折 好,右边向上对折,然后我们把它翻到背面这里注意看一下,我们从这个角向着上方这个中点连一条线,就像这样折出折痕,打开右边呢同样, 然后拿起来把左边这个打开,顺着刚才折的折痕把外边这个向里面推压平,然后把右边这个打开,把多余的部分放到这个口袋里面,上边向着这条折 对折打开,然后再加固一下刚才这条折痕,打开我们旋转一百八十度,这边跟刚才是一样的折法,如果你折这条斜线的时候不太容易操作,可以拿出一个卡片或者一个尺子辅助一下,直接对准这两个点压住,把这边压出折痕, 这样折的就比较直了,但是我自己还是比较喜欢用手直接折好,这样呢其中一个基础的单元就折好了,还是挺简单的吧,所以说接下来我们就需要简简单单的先折它九十个 好了。九十个都折好之后呢,下面我们开始来组合,我们先拿出两个,可以看一下这边多出来的 部分,可以插在这个口袋里面 拼成这个样子,看到了吧,然后拿出第三个把它拼在一起 好了,这样呢,我们就用了三个单元拼成了一组,那么剩下这么多单元怎么拼呢?其实这种花球类的组合折纸都是符合三五定律的,是什么意思呢?就是三个单元拼成 这一个面,然后用五个单元围成一个角啊,接下来我们就按照这个规律把他们都拼到一起。我们先以这个角为例啊,这里已经有两个单元了吧,然后继续用三个单元把他们 一共组合成五个单元,围成一个角, 然后把第一个这个角带到最后一个这个口袋里面。 折完之后还是看之前这里这个面已经组合好三个了,是吧?然后旋转一下,我们看这个面有了两个,还差一个组合一下。 好了,现在拼完了五个的人围成的角和他对应的五个面,现在这样看是不是像一个五角星一样?不过这个不重要,其实我们只需要围 绕着后面的新的角确定为五个单元围成一个角就可以了,这样就能把他们都组合到一起。 现在我有一个好消息和一个坏消息,好消息是我只用 三十个单元突然间就折完了,但是坏消息呢,就是我竟然多折了六十个,垃圾奢侈毁我青春。不过既然多折了,那还是把他们都拼完吧。 好了,现在三个钻子花球就都折完了,真的好大一只啊,并且他也很结实。好了,本期视频就到这里,我是倒车,请故意只做有意思的折纸。

beaming internet from the middle of the woods using an extra large pizza sized satellite dish placed on top of your house up to a satellite orbiting five hundred and fifty kilometers outside or a fatness fear well let's be honest is technologically mind blowing what's even crazier is that the starling satellites move incredibly fast around twenty seven thousand kilometers per hour and data is being sent back and forth between them at hundreds of megabits per second all while the dish and satellite are continuously angling or steering the beam of data pointed directly between them on top of that the dish switches between different satellites every four or so minutes because they move out of the dishes field of view rather quickly if you have no clue to how this is possible stick around because we're going to dive into the multiple key technologies which enable satellite internet to magically work first, we'll explore inside the satellite dish and see how it generates a beam of data that is able to reach space second, we'll see how this dish continuously steers the beam so that it points directly at a satellite moving across the sky and third will dive into what exactly the dish and satellite are sending inside the beam that results in your ability to stream five hd movies or shows simultaneously this video is quite long as it's full of in depth details we recommend watching it first at one point, two five times speed and then a second time had one and a half speed to understand it is a complete technology so stick around and let's jump right in first, let's start by clarifying the difference between a television satellite dish, such as this one and the starlink ground dish, which elon musk dubbed dish mcflatface or dish for short tv dishes use a parabolic reflector to focus the electromagnetic waves which are the tv signals sent from broadcast satellites orbiting the earth had an altitude of thirty five thousand kilometers tv satellite dishes only receive tv signals from space they can't send data dishe however, both sends and receives internet data from a starling satellite orbiting five hundred and fifty kilometers away, while the starling satellite is sixty times times closer than tv satellites it's still an incredible distance to wirelessly send a signal and thus the beams between dishe and the starling satellite need to be focused into tight powerful beams that are continuously angled or steered to pointed one another compare this to tv broadcast signals which come from a satellite the size of a van and whose signals propagate in a wide fan that covers landmasses larger than north america table sized starling satellites however need to be in a low earth or orbit to provide for twenty millisecond latencies, which is critical for smoothly playing internet games or serving the web and as a result their coverage is much smaller thus, ten, thousand or more starling satellites all orbiting at incredibly fast speeds in a low earth orbit are required to provide satellite internet to the entire earth let's now open up dishy mcflatface at the back, we have a pair of motors in an ethernet cable it connects to the router note that these motors don't continuously move dishes to point directly at the starling satellite, they're used only for initial setup to get the dish pointed in the proper general direction opening up dishe, we find an aluminum structural backplate and on the other side we find a massive printed circuit board or pcb one side has six hundred and forty small microchips and twenty larger microchips organized in a pattern with very intricate traces fanning out from the larger to smaller microchips along with additional chips and including the main cpu and gps module on the edge of the pcb on the other side are fourteen hundredish copper circles with a grid of squares between the circles on the next layer there's a rubber honeycomb pattern with small notched copper circles and behind that we find another honeycomb pattern and then the front side of dishe so what are we looking at well in essence, we have one thousand two hundred and eighty antennas arranged in a hexagonal honeycomb pattern with each back of copper circles being a single antenna controlled by the microchips on the pcb this massive array works together in what's called a phase deray in order to send and receive electromagnetic waves that are angled to and from a starling satellite orbiting five hundred and fifty kilometers above let's zoom in and see how a single antenna operates here we have an aperture coupled patch antenna composed of six layers most of which are inside the pcb it looks very different from the antenna of an old school radio and is honestly incredibly complicated so let's simplify it we'll remove a few of the layers for now step through the basic principles of how we generate an electromagnetic wave that propagates out from this antenna to start at the bottom, we have a microscript transmission line feed coming from one of the small microchips this transmission line feed is just a copper pcb trace or wire that abruptly ends under the antenna stack, we send a twelve gigahertz high frequency voltage or signal to the fiend wire which is a voltage that goes up and down in a sinusoidal fashion going from positive to negative and back to positive once every eighty three pigoseconds twelve billion times a second or twelve gigahertz note that high frequency electricity works differently from direct current or low frequency fifty or sixty hurts household electricity for example above the copper feed wire we have a copper circle with notches cut into it called an antenna patch with dc or low frequency alternating current there wouldn't be much happening because the patch is isolated, but with a high frequency signal the power sent to the feed wire is coupled or sent to the patch exactly does this happen well as mentioned earlier a twelve diggerhert signal is applied to the copper feed wire when the voltage is at the bottom of its sinusoidal or trough we have a concentration of electrons push to the end of the feed wire thus creating a zone of negative charge which corresponds to the maximum negative voltage this concentration of electrons on the tip of the wire repels all electrons away including the electrons on the top of the patch and as a result these electrons are pushed to the other side of the circular patch thus one side of the patch becomes positively charged while the other becomes negatively charged thereby creating electric fields between the patch and feed wire like so however, when we reverse the voltage to the comprophied wire forty two peek a seconds later we have a concentration of positive charges or a lack of electrons at the end of the wire and thus the electrons in the patch float of the other side the voltage in the patch is flipped and the direction of the electric fields are also flipped because the feedwire voltage oscillates back and forth forty two peek a seconds between one peak and trough the electric fields in the patch will also oscillate as the electrons or current flows back and forth if we pause the oscillation we can see some of these electric field vectors or arrows from the patch are vertical and because they're equal and opposite they cancel out however, other electric fields are horizontal in the same plain of the patch and are called fringing fields these fringing fields are in the same direction and thus they add to each other resulting in a combined electric field pointing in this direction at the same time electrons flowing from one side of the disk to the other which is an electric current generate a magnetic field with a strength and direction or vector perpendicular to the fringing electric field vector as a result we have an electric field pointing one way and a magnetic field pointing perpendicular to that let's move forward in time to where the voltage on the feed line becomes positive and now we're at the peak of the sinusoid forty two peek a seconds later the charge concentrations or voltage as well as the current is all flipped and thus the electric and magnetic fields pointed in the opposite directions, electric and magnetic fields propagate in all directions and by creating these oscillating fields we've generated an electromagnetic wave which travels in the direction perpendicular to both the electric and magnetic field vectors because the two sets of field vectors are not all in the same plane, but rather are curved the propagating electromagnetic wave travels outwards in an expanding shell or balloon like fashion kind of like a light bulb on the ceiling let's simplify the visuals so we can see the peak and trough or top and bottom of each wave and note that the trough is just a vector pointed in the opposite direction additionally the strengths of these field vectors directly relate back to the voltage and signal that we originally sent to the copper micro strip feed wire at the bottom of the stack which means if we want to make these electric and magnetic fields stronger, we just have to increase the voltage sent to the feed line it's like a dimmer on a light switch more power equals a brighter light thus far we've been talking about this aperture coupled patch antenna as transmitting however, it can also be used for receiving a signal in this microchip called a front end module we switch the antenna from transmit to receive and turn off the twelfth gigaards signal when an electromagnetic wave from the satellite is directed towards dishe the electric fields from this incoming signal will influence the electrons in the copper patch thus generating an oscillating flow of electrons this received high frequency signal is then coupled to the feed line where it sent to the frontend module chip, which amplifies the signal thus these antennas can be used to both transmit and receive electromagnetic waves, but not at the same time two quick things to note first as seen earlier this antenna has many more layers and is more complicated than we've discussed for example here are two circular patches the bottom is used to transmit it thirteen gigahertz while the top to receive at eleven point seven gigahertz additionally there are two h slots and two feed wires to support circular polarization a reflective plane in the back, and also, there are multiple features for isolating the operation of one antenna from the adjacent, we've included these in many more details in the creators comments, which you can find in the english canadian subtitles the second note is that there are electromagnetic waves of all different frequencies from thousands of different sources passing through every point on earth, whether it be visible light from the sun radio waves from radio or cell, towers or tv signals from satellites or towers therefore in order to block out all other frequencies of electromagnetic waves these antenna patches are designed with very exact dimensions so that they receive and transmit only a very narrow range of frequencies and all the other frequencies outside this range are essentially ignored by the antenna, let's move on and see how a single antenna can be combined with others in order to amplify the beam to reach outer space this single antenna is only a centimeter as sow in diameter and using only it would be like turning on and off one light bulb and trying to see it from the international space station what we need is a way to make the light a few thousand times brighter and then focus all the electromagnetic waves into a single powerful beam enter the massive mister mcflatface pcb fifty five centimeters wide with a total of one thousand two hundred and eighty identical antennas in a hexagonal array the technique of combining all the antennas power together is called beamforming so how does it work well? let's first see what happens when we have two simplified antennas space the short distance away as mentioned before one antenna generates an electromagnetic wave that propagates outwards in a balloon shape at every single point in space there's only one electric field vector with a strength in direction and thus the two antennas oscillating electric field vectors combine together at all points in space in some areas, the electric fields from the antennas are pointing in the same direction with overlapping peaks and thus add together via constructive interference and in other locations they're opposite with one peak on one trough and thus they cancel each other via destructive interference we can now see that the zone where they add together constructively is far tighter or more focused than a single antenna alone when we add even more the zone of constructive interference becomes even more focused in what is called a beam front thus by adding twelve hundred and eighty antennas together we can form a beam with so much intensity and directionality that it can reach outer space now you might be thinking that the strength of one antenna duplicated twelve hundred and eighty times over would result in a combined power of well twelve eighty times a single antenna, but you'd be mistaken the effective power and range of the main beam from all these antennas combined is actually closer to thirty five hundred times that of a single antenna the quick explanation is that by having these patterns of constructive and destructive interference it's as if we took a single antenna multiplied it by twelve hundred and eighty and then placed a whole bunch of mirrors around it and left only a single hole for the main beam to exit through the long explanation requires a ton of math and physics so let's move on。


宝子们好呀,今天做圣诞星链,愿圣诞的星光如珍珠般温柔伴你岁岁年年。圣诞的星星被我串成链了。珍珠血星链也太好看了吧!温柔到骨子里,圣诞带它氛围感直接拉满。


乌克兰战争以来,星链大出风口,这个小卫星组成的低轨道卫星群,用不断飞过的卫星接力通信,不仅用较低的功率实现卫星通信, 也具有低的多的延迟时间。更重要的是,地面上只需要一个锅盖大小的天线就可以上传信号,数据率大体与低标准刺激相当,下载当然更没有问题,速度快好几倍。新店是民用的,但有显而易见的军用潜力, 马斯克也确实在与美国军方密切合作细节上保密的。乌克兰战争爆发后,马斯克捐献了一批便携式地面战给乌克兰,但马上接着声明使用要小心,有可能被电磁侦查锁定。 没错,地面站在发射信号的时候,很难不被空中的电子侦查平台截获。新店很有特征的信号,更是暴露自己的性质。你不是要 打星链吗?我在这呢,快来打吧!但更加彻底的办法无疑是直接打掉星链卫星或者是其失能。 新店属于低轨道卫星,只有五百多公里高,为了有效覆盖地球表面,新店卫星的轨道固定,而且不断发信号,很容易跟踪。 从反卫星技术角度来说,不难打。麻烦的地方在于数量,星列已经在轨有两千多颗,计划总数超过一万。按照常规的反卫星打法,一枚导弹打一个卫星,那是要把任何国家打破产的,必须另外想办法。 星链卫星之所以能海量发射,是因为用了小卫星,要么一件多星发射,要么在大型卫星发射时用,没有用足的剩余载客重量搭载发射,这样使得发射成本极大下降,反星链也必须从低成本发射入手。星链的轨道低,对于地球 表面任意地点的过顶窗口小,需要密集布,不仅多个卫星的轨道倾角相近,同一倾角的平面上还有相继多个卫星,这即便于密集发射,也便于极速打星。 反星链也不需要全球追着打,只需要把轨道的地球表面投影,经过关键地区的经验卫星打掉就可以了。而且低轨道卫星是反复重仿的,守株待兔就行。 星链卫星的个子小,只需要小型战斗部就能有效杀伤星,在机动能力有限也简化拦截,这样一打一片,关键地区的覆盖就是出现中断,几个回合下来不补星,就可有效的关闭星链对关键地区的覆盖了。 另一个办法是轨道雷,星链不是一天里建成的,搭载发射是降低发射成本的重要一步。轨道雷在平时在轨道 上无害飞行,在战时变轨机动直行拦截,这些轨道雷也可以通过搭载发射在轨道上预先部署。不过这涉嫌违反禁止外层空间军事化的国际条约,需要有一个合理合法的理由。我星奉命撞击你星也是一个办法。 中国也在部署经验一类的技术,不光有低轨道通信小卫星,还有光学和 sar 雷达,在必要的时候转为自杀卫星也可机会星链卫星。当然这是杀敌一千自损一千的做法,只有万不得已的时候才用。 激光或者高能微波是更加先进的手段,从地面直接攻击,收到功率的限制较小,但受到大气扰动和吸收的影响较大,在轨道上底镜攻击功率要求大大降低,实际上更加可行。气动辅助变轨的禁地 飞行器特别适合干这个,可以反复入轨,一次出航中攻击多个小卫星。这是介于高超因素飞行器和轨道飞行器之间的新型飞行器。美国的 x 三七就是用来研究相关技术的,但中国后来之上 并且在空间成功的试验过,使用化后,这是理想的反卫星平台,除了硬杀伤还有软杀伤。星链卫星相当于手机基站底金部署干扰卫星可以有效的扰乱星地通信。星地是一方面,星际是另一方面。 如果发起用户和最终用户都在同一个基站范围内,星链卫星直接包干了。就像常规的地面基站一样,如果需要不同的基站覆盖,需要有光纤干线接驳。星链也是一样,只是有两个途径可用,一个是下传到地面站,然后 通过地面站之间的光线干线接驳在上传到目的地上空的经典卫星在下传到最终的移动应付。这好比常规的手机基站搬到低轨道上,基站与光纤干线之间多了一道新地恋路。其他照常在这样的情况下干扰。与上面相同。 在军事上更有意义的是星际直接中纪星令卫星之间直接在轨道上用极高频或者激光电路,中纪完全不依靠地面的通信设施,毕竟暂时还能维持正常通信的情况比较罕见。 乌克兰还真是特殊军事行动,在这样的情况下,干扰卫星部署在星链卫星之间的直接连线上,可以有效的阻止中纪通信。反星链技术对反小卫星都有效,小卫星正在成为军事卫星的新方向。小卫星不仅成本低, 而且抵进地球表面,对于光学和雷达侦查、通信、电子监听,一进抵三窍。在乌克兰战争里,美国的商用光学地球观察卫星揭示了大量俄军动向,包括基府城外几十公里长的俄军车队、比尔江斯克被击中的俄军战舰和马里乌普尔的战况 分辨率为一米甚至零点五米级,具有显而易见的军事价值。还有更多的 sa 二小卫星,用测试雷达提供全天候雷达图像,同样可达一米级甚至零点五米级的分辨率。还有电子监听卫星等,在战时打掉这些耳目也是必须的。 另一方面,中国也在大力发展各种类型的小卫星,已经形成一定的规模。中国小卫星也有遭到攻击的可能,除了加强防范,只有大力研发打击手段,以确保互相摧毁 作为威慑。在莫斯科号沉默的当天,传说普京下令击毁乌克兰上空的星链卫星,后来证明为谣传。但四月十八日,美国宣布停止直接上升反卫星导弹试验,并呼吁世界各国也停止试验和部署。 到现在为止,只有美国、俄罗斯、中国、印度进行过反卫星试验。其中中国在二零零七年进行的是历史上规模最大的反卫星试验,也是难度更高的中轨道反卫星试验, 据说造成约一千七百个空间碎片。美国反应强烈,理由当然是中国试验制造了大量空间垃圾。 二零二一年十一月,俄罗斯也进行了一次反卫星试验,美国再次指控,这次是危害国际空间站上的美国宇航员的生命。美国的指控是虚伪的,美国已经具备反卫星能力。在 二零零七年中国反卫星试验后不久,美国马上也进行了反卫星试验,提醒中国,我也有这个技术。中国其实不需要提醒清楚的很,更重要的是,美国对空间侦查和通信能力的依赖超过任何其他国家。美国最需要各国停止反卫星能力的研发。 另一方面,乌克兰战争中清练的作用提醒人们,美国的呼吁基本上从来不是为了全球公益,中国一贯主张和平利用外层空间。具体到反卫星试验和反卫星技术,中国一贯坚持合理合法、有利有结的原则。中国会响应美国的呼吁吗?你猜?

来了,来了,中国人自己的星列啊,要出场了!一点三万颗卫星准备就绪。他们啊,是未来战场上出奇制胜的关键。在此,为科研人员点赞。 我们都知道啊,太空禁地轨道的资源有限。老马的星列呢,当前抢占的是离地三百五十公里、五百五十公里和一千一百五十公里。这三条最好的禁地轨道。星列间距很小,其他国家要想插队啊,基本不可能。 有些同学会问啊,这马斯克的星列有四点二万克,可咱们啊,只有一点三万克,怎么跟人家竞争啊? 很简单啊,近地轨道啊,是一个圆形,越靠近圆心,边长就越短。在更低的轨道部署卫星,就能用更少的卫星完成对地表的覆盖。而且啊,距离地面越 进,卫星的速度就越快,发射和太空维护的成本也会降得更低。所以啊,我们选择在距离地面三百公里以下的区域部署卫星。老马的初衷啊,也许是想造福人类。可一旦战争全面爆发,任何民用科技啊,都会变成战争利器。 星列啊,本质就是座超强的太空信号基站,他可以在任何地点提供强力信号。比如俄屋战争被困在深层地堡里的亚素营乌军,就是用星列和美国完成通讯,增加俄军的攻坚伤亡。 我欣赏马斯克给员工掌心为汽车降价的真诚做法。但作为中国人啊,我更知道,战争一旦白热化,星列很可能被老美抢来对付我们。所以啊,我希望我们国家的星列,在这场太空竞赛中取得最终的胜利。

上课了上课了!今天贾老师教你们用折纸的方法来做圣诞挂件。对角折,横着折,横着折完竖着折,临近两边向内折,紧接两次对角折。对角折完向上卷翻一面窝,两边向上向下各两折。折完之后翻一面, 转个圈,粘丝带粘在肩上。对对折,两侧都往中线折,加些胶水固定好。画个纸膜剪下来,剪出胡子和啾啾,粘上眼睛和胡子。白前红后粘啾啾,画上一个小笑脸。圣诞挂件完成啦!我是渣渣老师,记得关注哟!