imagine if I have hot metal piece I want to cool it as fast as possiple, should I put it in strong circulated water bath or just stick it between 2 thick copper plates ?  the calculated heat diffusivity of copper is :  thermal conductivity x specific heat x density = 385 x 0.385 x 8960 = 1328096 m²/s  while for water it is just : 0.6 x 4.2 x 1000 = 2520 m²/s only !!  so, the copper can transfere heat 527 times faster than water. should I expect that copper will cool the metal piece faster ? or there is something I missed make water have higher cooling power than copper plates ?
It is will known that increasing cooling of a metal casting will lead to finer micro-structure which mean higher mechanical properties. If I have 2 molds one is thick copper die ,&amp; second is just thin-walled copper cup or mold cooled by water. which one of them excepted to cool the molten metal i.e. aluminium faster ?   by calculation it seems that copper die have higher cooling power as it has higher thermal diffusivity , but in real life it seems water have more cooling power. I am so confused.
"A mice problem" vs. "a mouse problem" In my laptop (a Lenovo y470 ) there are three USB ports. One of those is USB 3.0 others are USB 2.0 . I do not know which one is what. When I copy data from my External HDD it transfers at 38MB/s from all of the USB ports. (Which is a good speed for USB 2 transfers, but to low for USB 3).  I used the device manager to confirm that I have one USB 3.0 port.    Is there a way a can figure out which port is 3.0 ? Can't install Oracle Java 8 in Ubuntu 16.04 Ubuntu 20.04 on DualBoot fail 90% of tries - Initramfs unpacking failed: Decoding failed I just installed Ubuntun 20.04 on a Dell Latitude 7400 on DualBoot. I had to remove the RST as mentioned on this post :  It works but now I need to test 5 or more times to boot. After the grub screen, most of the time i have a black screen. Sometimes I have this error : Initramfs unpacking failed: Decoding failed And then it starts.  here is a file called initramfs.conf cat /etc/initramfs-tools/initramfs.conf MODULES=most  BUSYBOX=auto  COMPCACHE_SIZE=&quot;&quot;  COMPRESS=lz4   DEVICE=  NFSROOT=auto RUNSIZE=10% How to calculate temperature in Wire? Let's say I have 1m of 2,5mm² copper wire, insulated with H07V-K. The wire carries 40A and environment temperature is 25°C. The wire is suspended in free air. How hot will the wire get? And how can I calculate it for other values?  The use case is a 12V-230V AC converter I want to hook up to my car and determine the minimum wire thickness required. Because it's only used from time to time and not buried in a wall I suspect I can use thinner wires. This is a temporary thing and doesn't need to be up to code. I have a Toshiba z830 with ubuntu 12.04. I could use without problems the DSL connection (I have no router, only a modem) at home until a couple of days ago:   It stopped to work when while connected with the DSL connection via CiscoVPN (to my workplace), I had to leave the laptop unattended for a while and I guess the laptop tried to go to suspend. When I came back there were many messages on a black screen (sorry, I cannot attach an image because of my low reputation) and the laptop was not responding. I had to reset the it.   After rebooting it, the internet connection didn't work as did before (no browsing, no ssh, no skype, etc) although it says it is connected. I only can browse, etc when I connect to CiscoVPN to the same place where I was connected when it crashed.  When I am physically where I connected via VPN (at work) I can use the wireless, which I am not able to use now anymore since the incident described above.  Some additional information:  martillu@ubuntu:~$ cat /etc/resolv.conf   domain km.icrr.u-tokyo.ac.jp   nameserver 10.240.12.134   nameserver 10.240.12.135    martillu@ubuntu:~$ route -n   Kernel IP routing table   Destination Gateway Genmask Flags Metric Ref Use Iface   0.0.0.0 61.127.116.199 0.0.0.0 UG 0 0 0 ppp0   61.127.116.199 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0   169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 ppp0    martillu@ubuntu:~$ ifconfig   eth0 Link encap:Ethernet HWaddr e8:e0:b7:2f:bc:5a   inet6 addr: fe80::eae0:b7ff:fe2f:bc5a/64 Scope:Link   UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1   RX packets:17620 errors:0 dropped:1 overruns:0 frame:0   TX packets:13168 errors:0 dropped:0 overruns:0 carrier:0   collisions:0 txqueuelen:1000   RX bytes:19452232 (19.4 MB) TX bytes:2568218 (2.5 MB)   Interrupt:20 Memory:c0700000-c0720000    lo Link encap:Local Loopback   inet addr:127.0.0.1 Mask:255.0.0.0   inet6 addr: ::1/128 Scope:Host   UP LOOPBACK RUNNING MTU:16436 Metric:1   RX packets:134 errors:0 dropped:0 overruns:0 frame:0   TX packets:134 errors:0 dropped:0 overruns:0 carrier:0   collisions:0 txqueuelen:0   RX bytes:36316 (36.3 KB) TX bytes:36316 (36.3 KB)    ppp0 Link encapoint-to-Point Protocol   inet addr:219.167.252.226 P-t-P:61.127.116.199 Mask:255.255.255.255   UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1454 Metric:1   RX packets:17608 errors:0 dropped:0 overruns:0 frame:0   TX packets:13129 errors:0 dropped:0 overruns:0 carrier:0   collisions:0 txqueuelen:3   RX bytes:18993590 (18.9 MB) TX bytes:2221195 (2.2 MB)    wlan0 Link encap:Ethernet HWaddr 9c:b7:0d:d9:21:f3   UP BROADCAST MULTICAST MTU:1500 Metric:1   RX packets:0 errors:0 dropped:0 overruns:0 frame:0   TX packets:0 errors:0 dropped:0 overruns:0 carrier:0   collisions:0 txqueuelen:1000   RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)    I think that: domain km.icrr.u-tokyo.ac.jp in the resolv.conf may be suspicious, since if I am not connected via CiscoVPN I do not know why it should appear "km.icrr.u-tokyo.ac.jp" (this is where I connect via VPN). Is it possible to paint only inside a stroke on illustrator? what i actually want to do is paint the same stroke with different colors in diferent segments of it but i can't do it...   Also... I've seen some tutorials that include editing a gradient but that would be very complicated and so would be to make a new stroke over this one, I just hope theres an easyer way XD  Edit per comment:  thats cool but not really what im looking for, what i want is lets say my stroke has the shape of a burger i want part of i to be bread color and part of it to be meat color... not one stroke over the other... i want something like this, imagine the jelly worm is my stroke: Write access without read access How do I remap a key in macOS Sierra, e.g., Right Alt to Right Control? Looking for a short story title about a "weird house" How to prove that 2017 divides $1^{2017}+2^{2017}+\dots+2017^{2017}$? How can I prove that $2017 \mid 1^{2017}+2^{2017}+\dots+2017^{2017}$? I tried proving it with the use of modulo, however it was to no avail. Afterwards, I  tried researching, for possible theorems, that may help, but that bore no fruit, either. Can you guys please help me proving it, as I am stuck? Thanking you in advance. Orthonormal basis with specific norm I need to show that $v_1,...,v_n$ is basis for $V$ whenever $e_1,...,e_n$ is an orthonormal basis for V and $v_1,...,v_n$ are vectors in $V$ such that $$\left\Vert e_i-v_i\right\Vert &lt; \frac{1}{\sqrt{n}}.$$ I know already that I only need to prove that they are lineary independent. Also I tried to prove it by contradiction, but I got stuck fairly fast. Any help, or hint how to prove it (with ot without contradiction) will be appriciated. View approximate number of users online Is there any way to view the number of users online at any given time (or even an approximation)?  This could be really useful to provide an indication of whether your question is likely to get answered any time soon.  It could also provide a bit of an indication for why your question is getting very low views - if there are only a few users online, then that could be the reason for little interest in a question, whereas if there are lots of users online and the question still doesn't garner many views, then maybe it needs to be rephrased or something.  I know that this can't be used definitively, but it could be used as a rough guide, and could also just be an item of interest.  Perhaps it could show the number of users that have been seen in the past 5 / 10 minutes? (Shouldn't be too hard, since each user page already shows the last time that they were seen). reference variable In some text it is given that we can't assign constant values to a reference variable. When I executed such a program I could do it. Is there any condition we can't assign a constant value to a reference variable? Which graphics formats can be included in documents processed by latex or pdflatex? Pgfplots: How to fill area under a curve in a 3d plot similar to \closedcycle in 2d Headers and font in KOMA-script I am setting up the layout for my bachelor thesis using scrbook as basis for a self-made documentclass with twosided print. I want a header containing the current part number and name on the outer side (left on even pages, right on odd pages), the current chapter number and name on the center of the head and the same for section on the inner side. I found this example in the KOMA-Script documentation:  \usepackage{scrlayer-scrpage} \pagestyle{scrheadings} \automark[chapter]{chapter} \automark*[section]{}   It puts the chapter on the outer side on even pages and the section on the outer side on odd pages. Sadly, I was not able to modify this to fit my needs because I do not really understand the way KOMA-Script works here. If a part starts but there is still no chapter in it, the place for the chapter shall remain empty (same for chapter and section). Can anyone help?  Furthermore, I would like to change all fonts that KOMA-Script changes (e.g. toc, section, chapter...) back to the default computer modern as I do not like the font KOMA-Script uses here. Is there a better way than changing all the fonts manually like this:  \addtokomafont{section}{\fontfamily{cmr}\selectfont} Why does unlocking the bootloader wipe phone? KeyboardViewer app is saved from this AppleScript.  on run {input, parameters}     if application "KeyboardViewer" is running then         quit application "KeyboardViewer"     else          activate application "KeyboardViewer"     end if     return input end run   Dock toggle save. Adding shortcut to above, needs some work...   Syntax error Can’t set application "KeyboardViewer" to some object. Access not allowed.  tell application "System Events"     set application "KeyboardViewer" to (keystroke "K" using control down) end tell Print file content without the first and last lines