I just installed Ubuntu 18 my Laptop and I am facing issue with WiFi adapater not found  and I approached lot of blogs but still not resolved my issue.  I approached below link WiFi works fine after installing but if I restarting my system then it issue again repeating with WiFi adapater not found.    Please provide the solution for this issue
How do I install Wi-Fi drivers for Realtek RTL8723DE device in Ubuntu 16.04?  lspci -v | grep -i network 02:00.0 Network controller: Realtek Semiconductor Co., Ltd. Device d723
OpenID support for Ruby on Rails application What is current state of the art for enabling OpenID login in Ruby on Rails applications?  This is a community wiki with up-to-date answers to this question. Authlogic The most advanced authentication solution seems to be .  It supports OpenID with .  It supports Rails 4 and 3. Rails 2 is supported in the rails2 branch. You may want to watch  (and the ). There is a sample application called . Devise Devise is flexible authentication framework for Rails.  It supports OpenID with . restful_authentication Another authentication library of choice is  Rails plugin.  Seems like you also need to install  plugin. You may want to watch (old, circa 2007) . Ruby OpenID Raw support for OpenID protocol is handled by  library. In particular, when $x=y=z$ isn't the above expression equal to 1 and not -1? Finder: keep sort-by per-directory What is the SKU of a motor? I came across an 'N20' motor, and I don't know what that means. As far as I can tell (and please correct me if I'm wrong), N20 is the SKU of the motor. What is the SKU? 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. Replace non-numeric with empty string Quick add on requirement in our project.  A field in our DB to hold a phone number is set to only allow 10 characters.  So, if I get passed "(913)-444-5555" or anything else, is there a quick way to run a string through some kind of special replace function that I can pass it a set of characters to allow?  Regex? Can it happen that the image of a functor is not a category? Most vexing parse I received my PhD in 2009 and my adviser will not provide a good recommendation for me. This is mostly because we have fundamentally different approaches to science, and in retrospect I see that I could have avoided a breakdown in our relationship if I had been more deferential.  At this point, I leave his name off of my list of references, but I suspect that a diligent potential employer might call him anyway. I would be willing to discuss any concerns that were brought up in such a call - indeed I think that doing so will help me to find a good fit in a new position - but I do not know if I should, or how to state this fact in my job applications.  I am currently finishing my post doc, and one recommendation has been to take another post-doc so that I at least have two supportive references from postdoc advisers - and that the additional publications will place less weight on recommendations. Still, others have told me that not having a good reference from my adviser is a kiss of death.   How can I most effectively handle this situation? Why are year, pound and mile in the singular form in the phrases below?   five-year-old children  20 pound note 10 mile run   Is that because they're acting as adjectives, which are always invariable in English?  Is it incorrect to say...   five-years-old children? 20 pounds note? 10 miles run? Proving inequality $(a+\frac{1}{a})^2 + (b+\frac{1}{b})^2 \geq \frac{25}{2}$ for $a+b=1$ If $a, b$ are positive real numbers and $a+b = 1$, prove that :  $$\left(a+\frac{1}{a}\right)^2 + \left(b+\frac{1}{b}\right)^2 \geq \frac{25}{2}$$  I can see that the value $\frac{25}2$ is attained for $a=b=\frac12$. But I do not know how to show that this is the minimal possible value.  Thank you. Recovering lost photos on iPhone 5s after restoring from iTunes backup I used to have an iPhone 4s and all the data from there is synced in my iTunes in my Mac. I just got an iPhone 5s yesterday and decided then to plug it to my iTunes. There was a welcome message and 2 options: whether to set up as new iPhone or set up as old iPhone (4s contents).  So to be able to make everything fast, I chose the latter, but then all the new photos in my iPhone 5s were deleted and were replaced with all the contents from my 4s. Is there any way I could retrieve it? I understand when we say current, we mean charge (protons/electrons) passing past a point per second. And the charges have energy due to the e.m.f. of the power supply.  Now tell me, if a lamp has resistance and you hook it in the circuit, how will the current stay the same? The charges obviously lose energy in the lamp and so become SLOWER, which should mean current decreases, right?  [Edit] All answers explained a bit of everything, so it was hard to choose one. If YOU are looking for an answer, please check the others too, in case the accepted one doesn't answer your question. Is it true that $\mathbb{R}$ and $\mathbb{R}^2$ are isomorphic as abelian groups? Eigenvalues and power of a matrix Drupal out of the box comes with a page (which is the default homepage) that is assigned to the node path.  How do I avoid users reach it, and redirect them to the actual homepage of the site? If the universe is expanding, what is it expanding into? Scheduling a team based activity with 10 different teams and X different games. Every team must meet each other ONCE but never twice, Hi there I am planning a ”Scavenger hunt”-like activity (I have no other words for this event), and I am having trouble creating the schedule.   The idea of this hunt/run/game/competition is that 10 teams will battle each other at X different mini games. The games on are team vs. team based, meaning that there will always be two teams on each post and one winner and one loser.  I require that every team fights every other team. Meaning that team 1 will have to meet team 2, 3, 4, 5, 6, 7, 8, 9, and 10, and team 2 will have to meet team 1, 3, 4, 5, 6, 7, 8, 9, 10 (and so forth). The amount of mini games must be so, that every team only meets the other teams ONCE each, but still they have to meet every team.  How many posts do I need to create, and how could I schedule the overall activity? (A table of rounds and teams would be much appreciated). In the Pottermore article on  it's mentioned that other fractional platforms exist (7 1/2, for instance). Is it ever stated elsewhere where these platforms lead? Perhaps you could get a connection from your hometown by accessing one of these platforms? For a submerged object, buoyant force ($F_b$) is defined as:  $$F_b = V_{\text{submerged}} \times \rho \text{ (density)} \times g \text{ (gravitational constant)}$$   Conceptually, the buoyant force equation says that buoyant force exerted is equal to the weight of the volume of water a given object displaced. Why? I went online to   and found the following explanation, but it seems like non-sequitur to me:      Explanation: When an object is removed, the volume that the object occupied will fill with fluid. This volume of fluid must be supported by the pressure of the surrounding liquid since a fluid can not support itself. When no object is present, the net upward force on this volume of fluid must equal to its weight, i.e. the weight of the fluid displaced. When the object is present, this same upward force will act on the object.