由：
上：
在： DIY, 创客, 物理学, 科技发明, 飞行
标签： , ,
带有： 0评论

Halbach array 的构建与模拟（二）

知乎上找到了一个系列文章——《Halbach array 的构建与模拟》，一共写了三篇，链接分别如下：

  1. Halbach array 的构建与模拟（一） – 知乎 (zhihu.com)
  2. Halbach array 的构建与模拟（二） – 知乎 (zhihu.com)
  3. Halbach array 的构建与模拟（终极版） – 知乎 (zhihu.com)

以下是全文转载。

阅读全文

由：
上：
在： DIY, 创客, 科技发明, 飞行
标签： ,
带有： 0评论

专利详情网址：US7757609B2 – Track switching for a magnetically levitated transportation system and method – Google Patents

Track switching for a magnetically levitated transportation system and method

Abstract
A magnetically levitated transportation system employs permanent magnet rails along a guideway that interact with permanent magnets on a vehicle. The rails are optimized to reduce magnetic mass and cost of materials, while maximizing lift force. The vehicle is stabilized in the lateral and yaw directions with feedback controlled lateral control coils that interact with the permanent magnet rails on the guideway. A track switching structure employs permanent magnet rails that gradually widen along a segment of track and separate into two identical diverging rails. Feedback controlled lateral control coils in a moving vehicle stabilize that vehicle over one or the other pairs of diverging rails, as directed by a control computer, thereby causing the vehicle to continue along one path or the other, with no moving or active elements required in the track.

Images (11)

          
Classifications
 B60L13/003 Crossings; Points

由：
上：
在： DIY, 创客, 极客地带, 科技发明, 飞行
标签： , , ,
带有： 0评论

Electromagnetic Levitation Quadcopter – YouTube（英文原版）




Obviously this “quadcopter” is a demonstration device, showing how moving magnets over a conducting surface can generate levitation. It has not been optimized to minimize losses or be an efficient mode of transport. I still think it’s pretty cool. I’m used to seeing light things levitated by induced currents but not a 100+ lb machine.

这个飞行方式承载能力很强。

中文字幕版：四旋軸電磁懸浮「直升機」 – Electromagnetic Levitation Quadcopter – YouTube




中文介绍版：电磁悬浮飞行器有多厉害？看完才知道，100斤是小儿科！ – 西瓜视频 (ixigua.com)

阅读全文

由：
上：
在： Arduino, DIY, Idea?!, iThink, 物理学, 理论物理, 硬件, 科技发明
标签： ,
带有： 0评论

内容来自维基百科：https://zh.wikipedia.org/wiki/声能

声能

声能是介质中存在机械波时，使媒介附加的能量。由于声波是质点偏离平衡位置的振动，所以声能定义为质点振动动能和质点偏离平衡位置所具有的势能的总和。

当质点振动位移很小时，也就是在线性声学范围内，一定体积流体的声能是[1]:

\[ W=W_{\mathrm {potential} }+W_{\mathrm {kinetic} }=\int _{V}{\frac {p^{2}}{2\rho _{0}c^{2}}}dV+\int _{V}{\frac {\rho _{0}v^{2}}{2}}dV \]

  • \(V\) – 流体的体积
  • \(p\) – 声压
  • \(v\) – 流体质点速度
  • \(\rho_0\) – 流体静态密度
  • \(c\) – 声速

声能密度

根据上面的表述，单位体积的声能，即声能密度可以写成：

\[ \epsilon ={\frac {p^{2}}{2\rho _{0}c^{2}}}+{\frac {\rho _{0}v^{2}}{2}} \]

平均声能量密度

如果对声能密度在一个振动周期取平均，则得到平均声能量密度[2]，即

\[ {\bar {\epsilon }}={\frac {p_{e}^{2}}{\rho _{0}c^{2}}}\]

其中 \(p_e\) 是有效声压。

参考

  1.  L. E. Kinsler, A. R. Frey, A. B. Coppens, and J. V. Sanders, 1999. Fundamentals of Acoustics, fourth edition (Wiley).第5.8节。
  2. ^ 杜功焕、朱哲明、龚秀芳，声学基础，第二版，第4.7节。

由：
上：
在： DIY, 创客, 飞行
标签：
带有： 0评论

Build a PRO FPV Racing Drone for ONLY $99 Full guide – 2018 UAVFUTURES $99 Build

视频原地址：https://www.youtube.com/watch?v=GFNGUDT_9_c




Step by step guide showing you how to build an AWESOME FPV racing drone for around $99. This build is SIMPLE, CHEAP and most of all results in a crazy fast FPV racing quadcopter with awesome performance at an even better price. IMPORTANT. enjoy the videos and want to support UAVFUTURES . head to https://www.patreon.com/uavfutures every bit helps us make more content for you.

GIVEAWAY details at bottom of description after component links.

PARTS – things usually sell out after I make videos on them so I linked a ton of extra components below that people can use if something sells out.

Pro Build
Frame – http://bit.ly/2w97dVd
SC/FC combo – http://bit.ly/2Na6RUT
Motors – 2600kv – http://bit.ly/samguk2207
VTX – http://bit.ly/2BIq5zT
also think about upgrading to the nice matek vtx to go full PRO – http://bit.ly/2ADgU1n
Camera – http://bit.ly/2PB11Oe
Props – http://bit.ly/2LpkHRI

BASE Build
Frame – http://bit.ly/2w97dVd
ESCs – http://bit.ly/2od6o9T
Flight controller- http://bit.ly/2BDY5x2
Motors DYS $10 – http://bit.ly/samguk2206
Motors cheap version http://bit.ly/2PAEnW4 but get the samguks VTX – http://bit.ly/2Lk6h5b
Camera – http://bit.ly/2w6qvLg
Props – http://bit.ly/2PBJZj1

IMPORTANT I know things sell out, A LOT and people might want other parts so there are some other links to new parts below. All of which will be great to build with.

Other frames Martian – http://bit.ly/2o7xBuw Transtec frog – http://bit.ly/2MNd1xr Liberalist – http://bit.ly/2BI3cwn TBS source1 – http://bit.ly/TBSframe Diatone GT – http://bit.ly/2Ne95CE LSX5 – http://bit.ly/2MKvD0R Rooster – http://bit.ly/ArmattanRooster

MOTOR CHOICES Samguk Wu series – http://bit.ly/samguk2206 Samguk Shu Series – http://bit.ly/samguk2306 Samguk Wei Series – http://bit.ly/samguk2207 Cheap Racerstars but really spend a tiny bit more and get the samguks

OTHER ESCS 4 in 1s Racerstar 35 amp bl heli S – http://bit.ly/2o7xMGc PG 50 amp 32 bit – http://bit.ly/2PAv4W8 Racerstar Tatto 25 amp – http://bit.ly/2wb08DH RS 20 amp – http://bit.ly/2MJXQFe

individual escs RS lite 35 amp – http://bit.ly/2BJvgzy Hacrc 35 amp – http://bit.ly/2OZgmH2 RS 20amp – http://bit.ly/2w7pkLu RS m series 35 amp – http://bit.ly/2LlHs93

combo ESCs with FC built in tattooF4 – http://bit.ly/2AGFvR7 Starf4- http://bit.ly/2Na6RUT DYS stack – http://bit.ly/2nGU18y

F4 Flight controllers DYS F4 – http://bit.ly/2OVTmZm HakRc – http://bit.ly/2w928MH Matek – http://bit.ly/2PAfrhc DalRc- http://bit.ly/2BJlMnY Speedybee – http://bit.ly/2w6pjHy

Other FPV Cameras Caddex micro – http://bit.ly/2iCTIGg Micro Arrow v2 – http://bit.ly/2o7SHsC eagle 2 – http://bit.ly/2PzqG9N Foxeer Falkor – http://bit.ly/2MwyYS3

Other VTXS tx805 – http://bit.ly/2BFvisg Stealth – http://bit.ly/2Pzl5As black knight – http://bit.ly/2w93vLl matek vtx- http://bit.ly/2ADgU1n

Props Avan Flows – http://bit.ly/2NdBo4k king kong – http://bit.ly/2w7svmo Cyclone – http://bit.ly/2BIeAsd 4blade RS – http://bit.ly/2o6z0S7

Antennas – pagoda – http://bit.ly/2My1DpE aomway omni – http://bit.ly/2NdifPT Aomway stick – http://bit.ly/2PxE26x UXII – http://bit.ly/2MS9yNU

FPV GOGGLES Aomway Commanders – http://bit.ly/CommandersAomway Viper goggles – http://bit.ly/FXTviper

DRONE RADIOS QX7 – http://bit.ly/2AXlich X-lite – http://bit.ly/Frskyxlite i6 – http://bit.ly/2w7vDi8

MAKE SURE IF YOU ENJOYED THE VIDEO TO LIKE, SUBSCRIBE AND HIT THE NOTIFICATION BELL OFFICIAL GIVEAWAY RULES 1. To enter for the “base version” Watch the video and leave a comment about either a) what you like or enjoyed about the build OR b) leave a comment detailing how this might help get others flying 2.To enter for the “PRO version” Leave a meaningful “reply” to someone else’s comment, offering advice, opinions or helping someone out. (meaningful means more than 2 sentences) 3. Open to everyone, but winner might pay shipping depending on where you live. 4. I will leave a comment on your most recent video, and also link your channel as the winner on our discord server. here – https://discord.gg/GhXyRZB 5. winners will be chosen with a random comment picker but must fulfil rules 1 and /or 2 to be valid. 6. youtube is in no way affiliated with this competition. YouTube is not a sponsor of this contest and I release YouTube from any and all liability related to this contest. https://www.youtube.com/yt/about/poli…

由：
上：
在： DIY, 创客, 物联网, 电脑技术, 硬件, 网络网站
标签： ,
带有： 0评论

转载自：https://post.smzdm.com/p/az59qdwo/

软路由搭建攻略：从小白到大白

写在最前

本文写于2018年12月3日，其中的硬件软件资讯随时可能更新换代，请阅读本文的同时结合搜索引擎更新相关资讯。

最近突然很流行【软路由】这个关键字，然而在搜索引擎搜索出来的文章大多都相当硬核，让许多想尝试的小白望而止步，所以我就通过自身的经验简单的普及一下软路由的基础知识，以及软路由的搭建教程，因为这方面的文献比较少，多数都是本人自己胡说八道，如果文章中有什么错漏欢迎大家指出来，我会及时修正。

这篇文章接下来会说什么：

  • 软路由的定义
  • 软路由的优缺点
  • 什么人会使用软路由
  • 软路由的挑选
  • 软路由的组建
  • 软路由的设置
  • 硬路由桥接软路由发射WiFi

    这篇文章不会涉及的知识点：

  • 软路由虚拟机多系统（对于新手来说太麻烦而且我个人觉得暂时没有必要）
  • 黑群晖之类的NAS搭建（三大妈已经有其他作者写过啦）

    总的来说就是作者会尽可能的从新手的角度出发，尽量让各位小白都能看懂然后早日打造出自己的软路由


    什么是软路由

    在了解什么是软路由之前，我们先定义一下【硬路由】这个关键词，硬路由就是我们现在随便在京东淘宝搜索【路由器】搜出来的，从一开始就是按照路由器规范设计出来的硬件设备。而相对的【软路由】则是指，利用现有的硬件（可能是电脑或者树莓派之类的）配合软件来实现路由器的功能。

    软路由能做什么

    软路由对比硬路由优势在哪里？

阅读全文