How can I disable "global' search in the Salesforce1 (SF1) hamburger menu?

Question: I am exposing a single lightning component tab in SF1 and have a profile that limits object exposure to only the relevant objects (no standard objects). This works fine. However, global search in SF1 allows a user to reach custom object records and while they don't have edit rights on those records, they can view them and it makes the UX in SF1 odd. Is there a way for me to disable that component?
Answer: It is NOT possible to disable the global search in Salesforce1. You can however control which objects show up in Salesforce using the solution mentioned on this thread.
Quoting the relevant text here

Description When a customer has access to a standard or custom object
  via the + (tabs listing) ONLY but cannot access that object via an
  application, they will notice that these objects are not available in
  the Salesforce1 left menu.
Resolution Many users associate the tabs (objects) in Aloha with the
  objects available in Stage Left in S1. When a tab is not available in
  the Aloha UI via one of the available applications, that object will
  not be shown within the Salesforce1 Stage Left.
Users experiencing this issue should:
1) Click on the + to the right of the visible tabs within any
  application 2) Choose 'Customize my tabs' 3) Select any appropriate
  application and ADD the Standard or Custom object to the 'Available'
  column 4) Save
Now, the added objects should appear under the Salesforce1 Recent
  Items section.
Comment: Thank you Gaurav, however, My use case is limiting access to which objects can be searched in SF1 while maintaining read/view all for them in the desktop. I probably can only go as far as I have using navigation limitations.
Comment: Just checking, Gaurav - behaviour still the same in 2019?


What would happen to a star if a Dyson sphere lined with mirrors reflected a significant portion of the stars light back to the star

Question: I have looked for similar questions here on stack exchange. The closest example to this that I found is Could a Dyson sphere destroy a star. That question assumed less than perfect absorption of material lining the inside of the sphere, and the effect of thermally re-radiating it inside the sphere.  A lot of the answers focused on that much of the thermal radiation would not be reflected back to the star, and is likely to be reabsorbed by the sphere at another location. On the other hand, this question asks what would happen if the Dyson sphere, using mirrors, deliberately refocus a significant portion of the rays directly back at the star.
Comment: There's a great new article in *The Astrophysical Journal* on this topic:  [Evolutionary and Observational Consequences of Dyson Sphere Feedback](https://iopscience.iop.org/article/10.3847/1538-4357/ac3421), Macy Huston and Jason Wright 2022 ApJ 924 78
Answer: A partially reflective Dyson sphere is equivalent to asking what happens if we artificially increase the opacity of the photosphere - akin to covering the star with large starspots - because by reflecting energy back, you are limiting how much (net) flux can actually escape from the photosphere
The global effects, depend on the structure of a star and differ for one that is fully convective, or one like the Sun that has a radiative interior and a relatively thin convective envelope on top. The phenomenon could be treated in a similar way to the effects of large starspots. The canonical paper on this is by Spruit & Weiss (1986). They show that the effects have a short term character and then a long term nature. The division point is the thermal timescale of the convective envelope, which is of order $10^{5}$ years for the Sun.
On short timescales the nuclear luminosity of the Sun is unchanged, the stellar structure remains the same as does the surface temperature. As only a fraction of the flux from the the Sun ultimately gets into space, the net luminosity at infinity will be decreased. However things change if you leave the Dyson sphere in place for longer.
On longer timescales, in a star like the Sun, the luminosity will tend to stay the same because the nuclear burning core is unaffected by what is going on in the thin convective envelope. However if a large fraction of the luminosity is being reflected back then to lose the same luminosity it turns out that the radius increases and the photosphere gets a little hotter. In this case, the radius squared times the photospheric temperature will increase to make sure that the luminosity observed beyond the Dyson sphere stays the same - i.e. by $R^2T^4(1 - \beta) = R_{\odot}^2 T_{\odot}^4$, where $\beta$ is the fraction of the solar luminosity reflected by the sphere.
The calculations of Spruit et al. (1986) indicate that for $\beta=0.1$ the surface temperature increases by just 1.4% whilst the radius increases by 2%. Thus $R^2 T^4$ is increased by a factor 1.09. This is not quite $(1-\beta)^{-1}$ because the core temperature and luminosity do drop slightly in response to the increased radius.
It is probably not appropriate to quantitatively extrapolate the Spruit treatment for very large values of $\beta$, but why would you build a Dyson sphere that was highly reflective? Qualitatively, the envelope of the star would expand massively in response to the heat being deposited in it from outside and in this case the photosphere might become cooler, despite the extra heat inflow.
The above discussion is true for the Sun because it has a very thin convection zone and the conditions in the core are not very affected by conditions at the surface. As the convection zone thickens (for example in a main sequence star of lower mass), the response is different. The increase in radius becomes more pronounced; to maintain hydrostatic equilibrium the core temperature decreases and hence so does the nuclear energy generation. The luminosity of the star falls and the surface temperature stays roughly the same.
Comment: @KeithReynolds Yes, I see. And I believe what I've told you above concurs with those ambitions. In answer to your other point, I think as the star expanded, the convection zone would get thicker. This is because although the temperature gradient decreases, the maximum possible radiative temperature gradient (before convective instability sets in) is controlled by the opacity, which increases with decreasing temperature.
Comment: "The above discussion is true for the Sun because it has a very thin convection zone" it would be interesting to determine how the convection zone would change with a lower thermal gradientc between the sun's surface and just below then convective zone. Wouldn't the convection currents slow down causing heat below it to build up? If so, then the volume just below it should also expand and lift the convective sphere. Could The new lower density volume now participate in convecting.
Comment: "why would you build a Dyson sphere that was highly reflective?" 1. Hopes of actually slowing the stars fusion to help ensure a longer life for an advanced society. 2. To increase the size of the star along with its convective layer with the hopes that the reduced fusion rate allows for a smaller habitable dyson sphere. Hopefully drop the stars surface temps enough that it can be mined, while a larger convection zone caries heaver elements up from below.
Comment: There's some great info in  [Evolutionary and Observational Consequences of Dyson Sphere Feedback](https://iopscience.iop.org/article/10.3847/1538-4357/ac3421) by Huston & Wright.
Answer: An analysis would have to look at the effects over time. With my limited understanding of physics and intuition, I see the outer layers of the star reabsorbing the rays. Where the outer portions of the star until now have experienced large amounts of energy flowing in one direction, now has a net outward energy flow of maybe 1/2 to 1/10 of what it used to.
Initially, I see the inner core should continue it's fission process as normal. I see the outer layers absorbing much of the extra energy and begines to expand outward.
Assuming so far I am on the right track, and say at some point the star has grown to fill 1/2 of the volume of the Dyson sphere, much of the matter is significantly displaced. Though the center of gravity has not changed, if I am correct, there should be less pressure on the core and it should have shrunk, and thus the rate of fusion has slowed down and the radiation emitted from the surface of the star should now be much cooler than when the mirrors first began to redirect the light back to the star. Furthermore, the star's rotation would have slowed down; solar flares would be smaller or none existent. The last statement may not be true for awhile until the core's spin also slows down.
Ultimately, If i have not made an error in my general assumptions, maybe it could be possible to expand and cool say our sun to maybe fill a Dyson sphere the size of of a Mercury or Venus orbital diameter. That reduced fusion rate in the sun would reduced the habitable zone radius, making a habitable small Dyson sphere more easily realizable for an advanced civilization.
a little off topic but heat pipes with turbines in them could have their evaporators on the inside the Dyson sphere and their condensers on the outside. Concentrating the thermal energy though heat pipes would give an advanced civilization a way to collect thermal energy and allow them to build a habitable Dyson sphere even smaller than what is typically considered the habitable zone around a star.
Seeking confirmation, corrections, comments, and or other possible answers.
Answer: In Orion's Arm, this is called a Starbooster, and it has the effect of heating up the star's outer layers, causing its spectrum to shift upwards. It's typically used to change an M- or K-class star into a Sun-like G-class.
That said, Orion's Arm is science fiction (albeit science fiction that purports to be as realistic as possible), so I'm not sure how realistic this is.


Any good scuba diving on Ko Samui, Thailand?

Question: For my upcoming trip to Thailand, are there any good scuba diving spots on Ko Samui? We'll be there in March of 2013.
Answer: Haven't been there myself, but drawing from Wikitravel's Ko Samui guide and my copy of LP: Thailand's Islands & Beaches (published July 2010), here's some information:
Wikitravel:

The usual panoply of watersports are available, including plenty of
  dive shops, but most diving is done either in the nearby Ang Thong
  Marine National Park or Ko Tao as the visibility around Samui's sandy
  beaches tends to be poor. You can book diving day trips at dive shops,
  most of which are based in Chaweng. The dive boats tend to leave from
  the pier at Bophut and Bang Ruk.

Lonely Planet tends to agree:

If you're serious about diving, head to Ko Tao and base yourself there
  for the duration of your diving adventure. If you're short on time and don't want to leave Samui, there are plenty of operators who will take you to the same dive sites (at a greater fee, of course). Try to book with a company that has their own boat (or leases a boat)—it's slightly more expensive, but you'll be glad you did it. [...]
Certification courses tend to be twice as expensive on Ko Samui as they are on Ko Tao, largely due to extral petrol, since tiny Tao is significantly closer to the preferred diving locations.

LP mentions Ang Thong too, but not in "Diving" section but "Other water activities":

For those interested in snorkelling and kayaking, book a daytrip to
  the stunning Ang Thong Marine Park.

However, slighty contradicting itself, the "Do" section on Wikitravel  also says:

The sea visibility in some places around Ko Samui is almost very good
  (distances of up to 10-30 meters). One can enjoy splendid sights of
  underwater mountains, coral gardens, undersea rock formations, hard
  and soft coral and whale sharks when in season.

...and goes on to recommend Samran Pinnacles (for experienced divers) and Ko Kra & Ko Losin.
So, if "almost very good" is good enough, check out the places around Ko Samui. :) Otherwise, if your schedule allows, head to Ko Tao for scuba diving.
Comment: @Greg comment: I'd suggest going to Koh Tao instead of Samui. IF you have bad weather, the dive boats may not run, especially if it's a smaller company. Tao you'll nearly always dive, especially with the bigger shops that have 40+ foot boats chartered.
Answer: All the good dive sites are close to Ko Tao but if you want to stay on Ko Samui you can easily book a day trip from Samui and they'll take you to the Ko Tao sites (more expensive than from Ko Tao). Sail Rock is considered the best dive site in the Gulf of Thailand. But talk to the guys on site to give you more advice.
Answer: I've been to both Island and if you are into scuba diving, you should definitely stay in Ko Tao. It is full of diving resorts and divers everywhere. The vibe is much different than Ko Samui which is more mainstream.
Comment: Welcome to the site. This is not a discussion forum, but a question-and-answer site, so you should upvote answers you agree with rather than repeating them. The [Help Center](http://travel.stackexchange.com/help) has guidelines for how to use this site.


File system relatime option

Question: If file system is mounted read only, does relatime option apply? (will it update file access times?)
Answer: No.  If the filesystem is read-only, new metadata cannot be written to it. This includes access times.
Answer: According to the official documentation :

The kernel used in Red Hat Enterprise Linux 7 supports another alternative — relatime. Relatime maintains atime data, but not for each time that a file is accessed. With this option enabled, atime data is written to the disk only if the file has been modified since the atime data was last updated (mtime), or if the file was last accessed more than a certain length of time ago (by default, one day).

We see that the answer is no.

File system relatime option


Possible to get SecureCRT to show windows, not tabs, in Windows taskbar?

Question: Upgrading SecureCRT from version 5.2 to 6.3, the behavior of the application in the Windows 7 taskbar changed so that clicking on the application icon brings up a list of each individual tab that is open, rather than a list of the windows that are open. As I keep a very large number of SCRT tabs open, this is horrible. Is there a way to get back the behavior of 5.2, where the taskbar brought up windows, not tabs?
Answer: The article SecureCRT 6.5 and Windows 7 Taskbar may relate to this problem :

To disable Aero Peek functionality within SecureCRT, follow these
  steps (assuming you're running SecureCRT 6.5 Official release or
  later):
Browse to the location of the SecureCRT configuration folder as
  displayed in Global Options, General, Configuration folder.
Close all instances of SecureCRT (and SecureFX, if you're running both
  apps on the same system with an integrated configuration).
Edit the Global.ini file and change the following line From:
<code>    D:"Disable Aero Peek"=00000000
</code>
To:
<code>    D:"Disable Aero Peek"=00000001
</code>
Save your changes to the Global.ini file and start SecureCRT.


1950s 'Space Patrol' episode

Question: Commander Corey and Cadet Happy (did he ever advance beyond the rank of 'cadet'?) board an old, abandoned space station that is about to be destroyed as a menace to navigation. Criminals hiding out aboard the station (which I distinctly remember was a von Braun-type wheel) capture them but the good guys save the day.
Answer: This is "Prometheus Bound for Destruction" (AKA "The Phantom Spaceship").

Episode #40 "Prometheus Bound for Destruction" September 29, 1951
Buzz, Tonga and Happy blast off to explore an obsolete space station
called Prometheus, which is orbiting Ganymede, Jupiter's fourth moon.
Prometheus is scheduled for destruction by Space Safety. Boarding the
station, the Space Patrollers are threatened by an old space criminal
who has hidden there for forty years and resists their efforts to
remove him. Preoccupied, they fail to hear the broadcast warning all
ships in the vicinity that hydrogen torpedoes will destroy the station
within minutes.
Space Patrol: Missions of Daring in the Name of Early Television

The station was a rotating-wheel.
Answer: IMDB lists Season 2, Episode 29 of Space Patrol as "The Derelict Space Station".

Episode #82 "The Derelict Space Station" July 19, 1952
Buzz, Happy and Tonga become involved in a harrowing adventure when
two dangerous criminals overcome the trio in a spaceship which goes
out of control and hurtles toward the planet Earth.
Merrick: Peter Mamakos
Klinger: Tom Daly
Space Patrol: Missions of Daring in the Name of Early Television
Comment: The title sounds right, but (unless my memory is completely scrambled - it  has been 50 years) it is not the episode in question. I distinctly remember the space station was a von Braun-type wheel, rather than the ball type in this story.

1950s 'Space Patrol' episode


OpenGL update for intel graphic

Question: It all started with me wanting to use OpenGL 4 to play games on my ubuntu 16.04 laptop. I was running on intel integrated graphics and even if the processor is suppose to handle OpenGL 4 I could not find a way to install it as intel drivers are already installed on 16.04.
However i quickly realized that I have another video adapter on my laptop : [AMD/ATI] Mars XTX [Radeon HD 8790M]
So I tried to make this one work by installing AMD proprietary drivers (fglrx). I activated them in the additional driver setting but I cannot for some reason switch from intel graphic to my AMD GPU.
I looked everywhere and trying a bit everything. Using amdconfig gives me: no suported adapter detected.
I am running out of ideas and would appreciate any advise.
P.S: I am no expert at ubuntu.
EDIT: AMD proprietary driver do not work on ubuntu 16.04. I would therefore try to get OpenGL 4 to work on intel graphics. The only information I got as for driver is that it is i915. The laptop has a i7-4810MQ which runs Intel® HD Graphics 4600. This is suppose to run openGL 4.3 ....
Answer: fglrx is not supported on 16.04.  See here for more details.
Comment: Great, so I am better off with the intel HD graphics since AMD open source driver won't support openGL...

OpenGL update for intel graphic


show that the equation $P(x)=0$ has at least two real roots.

Question: Let $P(x)=x^n+a_1x^{n-1}+...+a_n$, where $n$ is an even positive integer, the $a$'s are real, and $a_n \lt 0$. show that the equation $P(x)=0$ has at least two real roots. what more can you say about them?
I know that a polynomial has the same number of real roots as its highest degree and the fact that $a_n \lt 0$ prevents the polynomial from shifting up or down, removing one of the roots. Because $n$ is an even positive integer, the smalles the highest degree of the polynomial can be is 2, so this polynomial will have at least 2 real roots.
I know this but the question wants me to prove it somehow, and I don't know what I am supposed to show in order to prove it?
Comment: As $n$ is even, what happens with $P(x)$ when $x \to \pm \infty$? And what is $P(0)$?
Comment: You can also show that any complex or real $z$ with $P(z)=0$ satisfies $1+\max (|a_1|,...,|a_n|)>|z|>1/(1+\max (|a_0/a_n|,...,|a_{n-1}/a_n|))$ where $a_0=1$.
Comment: $P(0)=a_n$ where $a_n \lt 0$ and $P(x)$ goes to $\infty$ when $x \to \pm \infty$, is that really all I have to say to prove this because it makes sense graphically what you said
Comment: That's all, since then you can use the intermediate value theorem.
Answer: Maybe it is not formal enough, but $P(0)$ is lower than $0$, $P(-\infty)$ and $P(\infty)$ is higher than $0$. And $P$ is continuous. Therefore is must cross $y = 0$ both on the positive and negative side.


Report using lookup field

Question: I have lookup field (which is lookup to a object c) on account and the loopup object (c) contain a field name stage. Now i need to create a report on account on the base of different stage. For example: if i have 2 stage with name a and b where and 2 there are 2 records on c object records with different stage stage a-> A1 record and stage b-> B2 record, and now want to generate report on contact, on the base of stage on object c. Is it is possible, or is their any other way to do this task. Please guide me.
Answer: There are two ways to go about this. The first is to use formula fields to pull the value of Object C's "Stage" field onto the Account and/or Contact. Assuming that the Stage field is a Picklist, you would create a new Formula(Text) field on Account, and the formula would be something like this (adjust for actual object & field name):
TEXT(Object__r.Stage__c)

To create a formula on the Contact, it would be:
TEXT(Account.Object__r.Stage__c)

For best results, use the Insert Field button on the Advanced Formula builder. Once you have these formula fields, you can include them in regular Account & Contact reports.
Alternatively, you can build Custom Report types, and include this field by lookup. If you have a need to include the

Report using lookup field


How can the date for the 2020 US census legally be changed?

Question: The next US census is scheduled for 2020-04-01. In light of the recent COVID-19 pandemic it might become necessary to delay this. How can this legally be done (since the census is required by the constitution)?
Comment: Downvoter, please explain.
Comment: Seems fairly clear that "the census must happen" and "the census must happen in this year" and "the census must happen on this exact day-date" are three very different things, and only one is constitutionally relevant.
Answer: The date of the census is not specified in the US constitution.  It only says

The actual Enumeration shall be made within three Years after the first Meeting of the Congress of the United States, and within every subsequent Term of ten Years, in such Manner as they shall by Law direct.

There is no requirement that "ten years" be interpreted precisely to the day.  The date is fixed by statute at 13 USC 141(a):

The Secretary shall, in the year 1980 and every 10 years thereafter, take a decennial census of population as of the first day of April of such year....

This requires that the census seek data describing the population on April 1, 2020.  It does not require that census workers actually visit people on that day.  They could conceivably do it in mid August, for example, or at any other time.  Of course, that would probably reduce the reliability of the census.  Congress could pass a law moving the census date to another later date if they wanted to get a more accurate count of the population on that date instead of a less accurate count of the population on the first of April.

In fact, when I got home later in the day after writing this answer, there was a letter from the census bureau inviting me to submit my census survey through the internet.  I did that a few minutes ago, so if I die in the next two weeks, the census will be off by one.
The letter I got says that if I don't fill out the survey online, they'll send me a paper questionnaire.  If I don't fill that out, someone will come to visit.  The prospect of that happening on April 1st seems quite remote.


Should there be some kind of special award for the 10 millionth question?

Question: I couldn't help that the SO question count is getting close to 10M!  Hooray!  Should there be a prize awarded to the asker of that milestone question?
Comment: Sorry. An award for this would encourage idiotic questions being posted in order to try to be the recipient. We get enough idiotic questions already without encouraging more.
Comment: An answer would seem appropriate
Comment: What happens if the 10-millionth question gets deleted? Would the one after it be awarded? Will it still be the 10-millionth question if one before it gets deleted? Could deleting cause multiple 10-millionth questions? Including deleted ones, there must be 10 million questions already.
Comment: Someone should run a book on whether the 10-millionth question is going to be VLQ.
Comment: Do you want to encourage people to think of it like a badge, with whatever questionable content might result as that otherwise arbitrary number approaches?
Comment: @gregsdennis voting on meta is different. In you case people vote because it means they are not considering your idea something worth pursuing, not because the question is flawed.
Comment: I suppose it could result in a bit of trolling, but it seems to me that it's a somewhat respectable stat.  It could be something simple outside of the website, too.  For instance, a couple years ago, BitBucket acquired 1M users and released a t-shirt that was only available to those members.
Comment: Maybe you can do an anti-award, like a "It took you long enough" badge that's awarded to new members after the milestone is reached.  I just thought there was an opportunity to have some fun.
Comment: Just out of curiousity, is that just SO posts, or is that SE-wide?
Comment: Is what "just SO posts, or is that SE wide?"? SE wide, there are a lot of poor questions that are closed, and at SO specifically we get a large amount of garbage that needs to be cleaned up. Encouraging more by trying to *have some fun* just means more work to keep the noise and clutter down here. Attracting trash in order to get an award is counter-productive. What's next? An award for getting the most votes for being  spam? The most votes for being unable to Google? The most amount of letters that make actual words?
Comment: I think that a prize shouldn't be given out, but maybe the post should be labelled or given an identifying feature. I agree that many people would post spam to try to get the "prize", but this may be fixed by hiding the amount of questions posted until the 10 millionth is hit. Just a thought..
Comment: Ken, I think you're going off the deep end with this.  It seemed like an important thing.  Apparently it's not.  Or rather, it's more important to maintain the integrity of the site than to celebrate some "arbitrary number" of questions.  I agree with that, but at the same time, it seemed an appropriate question to ask.  And now it has been, and it seems we have an answer.  The site has completed its mission.
Comment: Actually, the 10 million mark has long been surpassed if you include deleted questions.
Comment: Why are people downvoting my question?  It follows the guidelines perfectly.  I thought voting was supposed to reflect the quality of the question.  It's well-stated.  The fact that it may be a bad idea doesn't detract from it's quality.
Answer: Absolutely not. An award for this would encourage idiotic questions being posted in order to try to be the recipient. We get enough idiotic questions already without encouraging more of them.
This site isn't about earning awards or anything else. It's about collecting knowledge that can be shared. Awarding people just for posting some milestone question is counter-productive. Do we award people for posting the question with the most letters that don't make words? The people who post the question that shows the least amount of effort to solve themselves? The most blatant copy/paste of homework? No, because it's noise and cluttter that we don't want.
Comment: And yet something was done anyway.  http://stackoverflow.com/10m
Answer: We will be celebrating the momentous event in general, here on meta, in a manner that doesn't create noise on the main site (beyond something in the community bulletin inviting anyone that cares here). It will be a celebration for everyone, not just the person that asked the question - we're just happy it happened.
Think of it like a conference where they feed you; some tables have pizza, some have noodles, some have grilled stuff and some have mind-blowing apple juice in unlimited quantities.
It will likely happen shortly after the event, because such things are nearly impossible to time, but we will be doing something :)
Comment: http://stackoverflow.com/10m


On elimination of Noetherian conditions in the geometry of schemes

Question: Grothendieck seemed to try to eliminate Noetherian conditions as much as possible in EGA.
For example, he developed the cohomology theory of schemes without Noetherian conditions.
On the other hand, the Hartshorne's book assumes Noetherian conditions to do it.
If one's main interest is in the geometry of varieties or schemes of finite type over Dedekind domains, does one need non-Noetherian theory like Grothendieck's?
Comment: If your Dedekind domain happens to be the ring of integers of some number field, then one often encounters the associated adelic rings, which are non-Noetherian.
Comment: I would say "yes". For a related question with good answers, see http://mathoverflow.net/questions/61935/quasi-compact-maps-in-number-theory
Answer: For the most part, the answer is "no"; most people who work with varieties will never need to worry about non-Noetherian rings.  But there are reasons to be open to the non-Noetherian setting.  First, they can actually come up (as pointed out in the comments).  As just one example, the normalization of a Noetherian ring can be non-Noetherian.  You can either work hard to show that the rings you care about don't have this pathology, or you can just relax and not worry about it.  Second, there is often no harm in working with schemes in general.  (One caution with Hartshorne:  often the Noetherian conditions are unnecessary, and not used in the proofs; and in some cases, the arguments are more complicated because of the desire to work in the Noetherian setting.)
My suggestion is this:  don't worry about reading how to remove Noetherian conditions until you have a need to remove them.  But don't gratuitously add Noetherian conditions for no good reason.  (Note also:  sometimes Noetherian conditions can be removed with little pain, see for example my answer Flatness for family of hypersurfaces.)
Comment: Fiber products of noetherian schemes ...
Comment: @Martin Noetherian conditions are not necessarily preserved by a base change. I guess this is one of the reasons why Grothendieck endeavored to remove them.
Comment: Thank you for your nice answer. I agree with you on Hartshorne.
Please let me wait for a few days before I accept yours.


What would all the forces on a space elevator be as it moves up and down?

Question: At the bottom, the acceleration due to gravity would be g. At the top, it would be something like .8g... But would the total acceleration effectively be 0 like on the ISS? How would the acceleration change, then, as it moves up?
Or, because the top of the elevator would be well beyond the center of gravity of the system, would its acceleration have an upward component at the top?
Answer: Well if you are talking of orbit of 330 km like the International space station. the gravity difference will be least and the maths will show centripetal acceleration will point upwards
It is important to note that even thought the satellites are travelling in a circular orbit they do not experience the effect of the centripetal acceleration because the satellite is in free fall.
According to the newton's cannon experiment the object in orbit is in free fall and experiences zero gravity.
There will be a upward component of acceleration because the space lift is not in geostationary orbit. the space lift with respect to the earth at the altitude of 330-450 km has not attained the orbital velocity but is at the velocity of $R*\omega,R\to \text{radius of earth+lift length},\omega \to \text{angular velocity of earth}$ which is not sufficient to experience the effect of zero gravity.
In order for the space lift ,given that it is connected to the earth should be at the geostationary orbit altitude to attain the characteristics of a satellite or in this case the ISS to have no upward component of acceleration on its crew.
Answer: If you treat the entire elevator as one center of mass M1 then you would have one force pointing away from the center of gravity of Earth (pointing down) or any other big object M2, but you would have an equaly big force pointing in the other direction of M2 (Pointing up). These two forces counter act each other while the elevator is moving at constant velocity but when the elevator would slow down at the top there is a external force acting on M1 slowing it down so the force downwards toward the center of M2 would be greater than the force vector pointing in the other direction, and vice versa when the elevator begins to slow down at the bottom.


Call the extrensic of a pallet from the ink smart contract

Question: I am using a DEX Pallet and it has multiple extrinsic functions, But I am thinking of developing a smart contract in Ink that will be calling the extrinsic functions of the pallet and the people who want to interact with DEX pallet extrinsic they will be dealing with the smart contract not directly with extrinsic. Is it possible? if yes how can I do that
Answer: You can do this by writing a custom chain extension and configuring it in your contract.
The guide shows you how to configure it in your contract https://use.ink/macros-attributes/chain-extension/ and this example https://github.com/paritytech/ink-examples/tree/main/rand-extension shows how to implement a rudimentary chain extension in your runtime.
As an aside, if the functionality of the contract is so reliant on the DEX pallet's extrinsics, why not implement it as a pallet instead?


mobile homescreen lost

Question: I have downloaded 2 icon packs for android. Now my phone don't work anymore.
I am working with smart launcher.
I can not even get in to settings or apps. My homescreen is black, but I can see on top the task bar, with notification for emails and our and I have netconnection.
what can I do??
Comment: What exactly are these "icon packs" you've downloaded?
Comment: Also, what Android version are you using? Please [edit] your question to add these details, so we can help you.
Answer: Try to go to setting by any way...
Like: in some launch screens you can get the settings screen via: options->Device settings or Drag the task bar ->Settings.
And then change the Home screen settings to previous home screen.
If these options not available, I think Factory Reset is the only option for you.
Answer: If your phone is connected to the net, try to install any other launcher from the play store website, for example:
https://play.google.com/store/apps/details?id=org.adw.launcher
Wait the installation to finish on your phone, then press the home button. Now you will able to uninstall then reinstall SL or any other launchers.

mobile homescreen lost


How can I connect an unthreaded boom spigot to a 3/8"connector?

Question: How can I connect an unthreaded boom spigot to a 3/8"connector?
Answer: With an adapter like this:

That's the Manfrotto 014-38 Rapid Adapter - 5/8" Stud to 3/8" Thread
Note that you can attach the 5/8" pin in either horizontal configuration (through the holes) or vertically (from the bottom).
Specific example for illustrative purpose — you can find these in other brands in various qualities and prices.
Comment: Super. 90° options. I saw that before at $23 and said absolutely not.
BH - $13; Amazon - $10. And for fun I will leave a review that says "Doesn't work on a Kindle."
Comment: $20+ does seem pretty rich. On the other hand, if you're attaching hundreds of dollars of equipment, or if failure at the wrong time could otherwise be costly — well, I'd at least avoid the super-cheap no-name ones.
Comment: Perfect. 90° as well. BH new - $13; Amazon $10; BH used $8! ... but you can't order until Tuesday night. Amazon done. Thank you.
Comment: You can get lots of variations on a theme, including ones with a removable 'hat' that supports both thread sizes too & becomes the stud end if required, 2 or 3 quid/bucks/shekels on eBay. BTW, did you try unscrewing that stud end/'hat'?


Expose filter in block to show results on view page

Question: I want to make custom search block on home page, in header region. I'm using Exposed filter block in Views module, but results on the page are shown just below the block, in header. I want results of the search to be shown on the other page, like regular search do. Is there a way to achieve this. I'm using Drupal 7.
Comment: Have you tried put exposed filter to a block, so you can assign the block to any region you want. And search result in content region. Is that what you are looking for?
Comment: I assigned my exposed block to header region but it shows results just bellow exposed box.

What I want to achieve is to have search box just like core Drupal search box but use Views modul and exposed filter to make something like that.

Problem is that with exposed filter I didn't find the way to make search results show on other page (to redirect results to other page rather than to show them bellow exposed search box).

Tnx!
Answer: Create a page view using filter you want.Step 1) Enable the block in your View

Step 2) Put the exposed filter block where you want it to be

Step 3 ) Test the result
Comment: Thank you so much. I cannot believe it was so simple. I was trying almost everything but the biggest mistake was that I was always starting with block and not with page itself.
Comment: What's defining that the results go in the content region? You left that out.
Answer: One more thing for people using "Content pane" display in views. You need to set "Use Panel path: Yes" in order to fix this issue.


Clash of Clans keeps crashing!

Question: So my clash of clans keeps crashing whenever I tap the friends tab to view my friends list. By the way I'm using BlueStacks to play Clash of Clans. Can someone please tell me why this happen? and how I can fix it. Thanks
Comment: Note that BlueStacks is not supported in any way by Supercell.
Comment: I highly recommend you switch over to andyroid its actually kept up to date with android on phones, bluestacks is a hunk of junk that is so outdated
Answer: It could be that because your using a app player, the game doesn't run properly. I don't know what could be the cause, but it could be a problem with the game installation. Get a data transfer code (In game settings), and reinstall the game.
Once you have the game again, use the code in the settings.
There also could be a unlikely chance that Bluestacks is not supposed to go in the friends tab because of missing apps, or files. In this case, I can't help you.
If these aren't the case, it might be something with your friends list that causes it to be accessible (which is probably not possible).
Sorry if none of this helps.

Clash of Clans keeps crashing!


How to authenticate a user in SharePoint server side object model?

Question: I am developing an Asp.Net web application that will access data in a list on a SharePoint 2010 server. Can anyone tell me how do I authenticate a user against SharePoint using the server side object model? What are the different possible methods that I can use use to achieve this? The question may be dumb as I am really new to SharePoint and I'm stuck with it. I know how to do it using ASP.NET web services exposed by sharepoint.
Answer: All users are by default Authenticated in SharePoint (unless you are using a zone with anonymous access). You don't have to do anything.
Impersonation, if that is what you actually mean, is done in the same way as in plain ol' ASP.NET.
Comment: Thanks for ur reply. I am developing an ASP.Net web application. But the data is present in Sharepoint lists. For some reasons i need to use server side object model. And my code will reside on the server. Now if I need to validate a user who has access to sharepoint site and I need to provide him access to my application by checking against his sharepoint credentials. How do I do it. Thanks in advance
Comment: If you're developing an application that is hosted outside of SharePoint you should use the Client Object Model or the SharePoint web services - not the SharePoint server side API (even though you can).


Shared IRQs in Linux

Question: When an IRQ line is shared between multiple registered interrupt service routines, what determines the order of execution of the ISRs when the interrupt line is raised?
Answer: The order is not predictable anyway because, as you said, the interrupt line is shared. So there are (or might be) other device drivers in the system that register an ISR on same interrupt line shared with your ISR. So you cannot assume in which order the ISRs are invoked !
Now when interrupt line is raised, the kernel invokes all ISRs that are registered for that that line, one-by-one, untill a certain ISR returns "CLAIMED".
The ISR gets a soft context that represents the device and it is up to ISR to check that this device is the source of interrupt. If yes, the ISR returns CLAIMED, otherwise NOT CLAIMED.

Shared IRQs in Linux


Share completions between running vim instances

Question: I use tmux for the most part instead of using vim tabs and splits. Does vim have the ability to share completions (via Ctrln and Ctrlp) between running instances? Is there a way to set it up where each of the vims are communicating with the server vim.?
Comment: No, this can't be done in a *practical* way. Vim is perfectly capable of handling dozens and dozens of buffers, use its power.
Comment: @romainl, could we have something written to a "completion file" from where `vim` would read and refresh its completion list?
Answer: Vim is able to use the same completion database if the database is external to each vim instance.
For example, completion will be somewhat 'shared' if you use ctags completion or youcompleteme or any other plugin that uses external processes or files.
Word completion is not quite useful for you because it will only use words in the same file: C-N/C-P
But omni and ctags completion will use ctags database (which should be built by exuberant ctags beforehand) and will be shared among all instances.
Type C-X C-O for omni-completion, C-X C-] for ctags completion.
Answer: In :help i_ctrl-n it shows that Vim uses the complete option to complete words. The help on complete goes on to show that the only real option to use something that is not local to the Vim instance is to use a dictionary file. The question then boils down to generating such a dictionary file using all vim instances. You could do this by parsing all open files every now and then. I have no idea of the impact this would have on performance though.
Another option would be to use an entirely different mechanic (ctags etc) but this might break functionality elsewhere as these were not really intended for simple autocompletion.
On a more general note, you could also change your workflow a bit to stick more to the way Vim was envisioned to be used. This would mean using one or a few windows to look at stuff simultaneously and switch buffers often. A plugin that does the switching part very nicely is ctrlP. After activating it by pressing a button it allows you to do a fuzzy search for files in various places, thereby allowing quick switching. As long as you remember the filename that is.


Is data Inside SharePoint Hosted App searchable?

Question: If I develop a SharePoint Hosted app which creates several lists inside the App Web, is that list data exposed to SharePoint's search engine? In other words, will I be able to perform search on data in my App Web?
Answer: No, not by default. You need to do a workaround like this:

Data on the app web is not crawled by the search indexers, so custom data must be deployed remotely or in the host web. This applies to all apps for SharePoint, but we note it here because apps intended for anonymous access often require search functionality.

Reference: How to: Create apps for SharePoint that can be used by anonymous users
Comment: Thanks. That's a huge drawback. From customer's perspective, if I buy an issue management app and I can't search in issues or query it like assignedto:me, then what value does it bring? Very disappointing.
Comment: How would it be to add the app domain as an external source for search? Is that blocked by Microsoft?
Comment: @RobertLindgren I read the statement as you should host your data externally (not in the SharePoint Farm), and use the App to update data on the external source. That external source can be crawled by SSA.
Answer: I've tested this in SharePoint Online (Wave 15) and found that data in lists in the app web IS searchable; Not only from the host web, but from other site collections that consume the search service. I haven't read anything about this issue being fixed, but it looks like it has. Do others find the same?
Comment: Are you sure that you get search results from app web?
Answer: This behavior is probably due to having a proxy configured in the Farm Search Administration dashboard ([CentralAdmin]/searchfarmdashboard.aspx) and the proxies not knowing how to route non Internet requests. You need to let SharePoint search know to not use the proxies for the AppWeb URLs, by adding a wildcard entry in the URL exceptions list
Check your ULS logs on the crawl server for errors with eventID du54.
Update

"Do not use proxy server for addresses beginning with:" to add http://[AppPrefix]* (and/or https://[AppPrefix]* if you use SSL sites).

The * must be present as AppWeb URLs are dynamically generated with each new app instance. (I wonder if this is one of the reasons MSFT even have an AppWeb prefix that needs to be defined?).
Note: You can determine the [AppPrefix] from Central Admin
[CentralAdmin]/_admin/ConfigureAppSettings.aspx


Arduino PWM to analog: RC filter vs DAC?

Question: I want to use an Arduino to control the throttle signal going to a high power motor ESC. The problem I have is as the Arduino outputs a PWM, the ESC reacts by pulsing the power to the motor. So I searched a bit and I understand that to convert the PWM output of the arduino to an analog signal I can use a RC filter. Also I was wondering whether DAC ICs actually convert PWMs to analog. Knowing that the Arduino has a PWM frequency of 490Hz, which of the two methods would you recommend?
Thanks for your help!
Comment: What dynamic qualities do you require in your analogue signal?
Comment: Very low voltage ripple and relatively fast settling time. The latter being the variable I can most compromise on.
Comment: ... and put into numbers?
Comment: I am not sure what is reasonable to expect. As I want to control the throttle of a bike, I need the throttle to be as accurate and constant as possible so a voltage ripple as close to 0 as possible. At the same time for PID control performance, comfort and experience the fastest response time possible is also ideal. I would say that higher than 100ms would start to be inconvenient but again I don't know if this is reasonable.
Answer: If your motor driver (AKA electronic speed control) is of the type used in radio controlled models, the expected speed control signal isn't just a voltage level. It listens for the RC servo "protocol": A constant frequency (usually 50 Hz) square wave with a high time between 1 ms (motor stopped on an aircraft, full reverse on car/boat ESCs) and 2 ms (full forward). While this is often called PWM, you can't just feed any PWM signal to it and expect it to work.

A servo control signal with the correct timing is easily generated by an arduino with the included servo library.

If the motor driver does actually expect a signal in the form of a voltage level (like some E-bike motor drivers, for example), you need an actual digital to analog converter (DAC) to set the speed.

As you already suggested, the easiest way is probably to use the PWM output library function analogWrite() and low pass filter the waveform. This is an actual, rudimentary form of a digital-to-analog converter, and should be more than good enough for your application.
You can use a dedicated DAC chip. While I have never seen a DAC chip which takes a PWM input (A PWM signal is actually not digital even though it only has two voltage levels, as pulse width is a continous analog property), you can buy DACs with either a serial (e.g. I2C or SPI) or a parallel(one input pin dedicated for every bit) interface.
Answer: PWM is one way of implementing Digital to Analog Conversion (DAC).  But not the only way.  It is NOT correct to say "DAC ICs actually convert PWMs to analog."
Your question is too complex to be answered as a simple generic question. There are many variables in the overall design which must be considered when deciding whether to use PWM or a more traditional method of conversion.
There had been hundreds or thousands of circuit designs implementing exactly the same function you are asking about.  Typically, motor controllers use the special UN-filtered form of PWM defined for traditional radio-controlled model aircraft, etc.
Your question appears to indicate that you have not yet sufficiently understood  the issue. Your question doesn't make sense as you have asked it.  Common motor speed controllers and R/C receivers, etc. do not use traditional DACs at all. They ultimately perform a DAC function, but they don't use DAC chips to do it.
Comment: In my specific case, I don't have a choice but to go through a PWM as I am using an Arduino. When I connected this to my controller, it actually pulsed for every wave so the motor response was not continuous at all. This is why I am searching methods to smooth it. All I want to know is if it would be worth putting a DAC between the Arduino PWM pin and the controller throttle input or if a RC filter will be sufficient with the appropriate characteristics.
Comment: @EliottW I don't mean to be rude, but it only takes 10 cents worth of components to make an RC filter and see what difference it may do - have you tried that? If you cannot quantify your speifications in numbers (P2P ripple etc.), then maybe you can try out some different RC-constants and see how it works for you ?


Copy settings and preferences to new mac

Question: I have a Mac at the office and will be buying a new one for home. Is there a way to move my preferences and settings from the old computer to the new one?
Answer: Yes, you can use the Migration Assistant software that's included in all recent versions of OS X. See here for Apple's instructions on using it in Mavericks. You'll need to be able to connect your old Mac to your new one, over a local area network (either wired or wireless) or using a Thunderbolt or Firewire cable
Comment: Will it copy over all the broken stuff? IE, for the life of me I can't get the copy screen shot selection to work anymore in chrome or some other apps
Answer: Simply copy the contents of your ~/Library from your old user account to your new user account on your new machine.
Comment: Would there be any permissions issues with doing it this way?
Comment: @dwightk There shouldn't be, but as with everything you should always do an ACL reset after it.
Comment: If I copy the library over and then install an application, will it write a new preferences file over my old one, or work off the old one?
Comment: @aszekely It'll use the old one


A food that doesn't have enough salt

Question: In English we use the adjective "saltless" to describe a food with "no salt"; but I need to know whether there is a particular adjective for a food which doesn't have "enough" salt? (i.e. intentionally for diet / or when a cook forgets to sprinkle enough salt etc.)
Answer: The usual way to say this (especially if you're talking about food you're cooking or eating) is "it needs salt" or "it needs more salt".
If it has to be an adjective, I would say "undersalted" or "not salty enough". For example, "The bread was really good, but the soup wasn't salty enough."
It's also possible to say "insufficiently salty", but that's very formal.
Comment: +1 "Under-salted" pretty much covers it.
Answer: I've never heard anyone say "saltless", and I don't believe that's correct English.
Americans would usually say it has "no sodium" or "low sodium", especially when we're discussing dietary or nutritional contents of a dish.
A dish is "too salty" or "has too much salt", or in cases where it needs more salt, the dish "tastes bland and needs more salt".
Answer: "Saltless" is not idiomatic for foods without salt.  Instead we would say they are "unsalted".

I'm going to buy us some peanuts.  Do you want salted or unsalted?

Foods without enough salt would be described as "under-salted", or simply, "needs more salt".
Answer: The fact we have no antonym for salty has recently cone to my attention.
For the time being, we can say unsalty.

A food that doesn't have enough salt


What G forces does a pilot perceive in a "1 G" barrel roll?

Question: This is a follow on to an earlier discussion about pilot perception of G forces compared with actual aerodynamic loads on an airframe.  Years ago, the Boeing 707 prototype famously did not one, but two 1G barrel rolls to impress potential buyers. I would imagine the expert pilot just kept the airframe at 1G positive load through the entire maneuver, which would put him weightless at the top of the roll (plane inverted).  Is this what actually happened?  How is this done?
Comment: He was not weightless at the top of the roll, he experienced 1G... Bob Hoover famously demonstrated this by pouring a glass of water while barrel rolling, the G force remained constant throughout the roll. I think you are trying to add the 1G aerodynamic load to the -1G of gravity to get to zero, but the force felt throughout the entire roll is 1G relative to the outside of the loop.
Comment: @RonBeyer  Bob Hoover pours iced tea while doing a barrel roll in this [video](https://www.youtube.com/watch?v=V9pvG_ZSnCc).
Comment: The title could use some improvement.  Do you really want to give the answer to the question in the title?  PS is there any such thing as a 1G barrel roll meaning 1G from start of initiation to very end?  Seems unlikely.
Comment: @quietflyer The title seems fine to me: what G forces does *the pilot* perceive when *the aircraft* is subject to 1G of aerodynamic forces?
Comment: G force on G-meter is same as G-force that pilot perceives, which is same as the G-load exerted on the aircraft structure.  It's all the same.
Comment: The only thing NOT the same as all of the above is the ACTUAL acceleration of the aircraft through space which offset -1G from the felt acceleration.  Two quick examples-- straight and level flight -- "felt" acceleration 1G, actual acceleration 0G.  "Zero G" ballistic flight-- "felt" acceleration 0G, actual acceleration 1G downward (i.e. -1G).
Comment: @ Tanner Swett PS if the title had been exactly as you stated than I would not have raised an objection.
Answer: You can't do a barrel roll at 1G.  It's a loop pulled out into a coil, and you have to pull pitch to get it started so you are going to be 1.5 to 2 starting out, declining to 1G to .5 at the top, and pulling 1.5 to 2 on the pullout.
So the sensation at the start is like a hard climbing turn (which is what you're doing), pressed into your seat with about the force of a steep turn at the start, declining to normal gravity or bit less (giving a bit of that giddy becoming weightless sensation, but not coming out of your seat) as you ease off the pitch coming around the top, and about the same pressed into the seat force as at the start, or a little more, on the pullout.
A good barrel roll should be no more than 2Gs peak, but how much is a function of pilot skill and of the airplane's ability to keep up the energy through the first half.  A jet with oodles of power to keep the speed up in the steep rolling climb can get away with a very gentle pull and will see only about 1.5 or less on the pull up and pull out.
But it's always going to be more than 1 starting out and finishing off and when Tex Johnston said in an interview it was a "1G maneuver", he really meant "not much more than" as in less than 2 (and no worse than a steep turn, unless you screw it up and fall out).  Watch the film of the barrel roll and you see a firm pull up at the start with a fairly steep nose down attitude on the exit, which would have required a pull of at least 1.5 G in returning to level flight without over speeding.
Comment: Outstanding answer John.  So the airframe is always positively loaded around 1.5 - 2 G, with pilot "feeling" 0.5 - 1 G at the top (being head down).  Perfect, thank you so much.  Now I'll work on the control inputs.
Comment: It's a weird sensation at the top of the roll, because "down" is blue sky, and "up" is green earth. Loops are similar, but the pull force and G load at the start and end is much higher because all the energy is directed in the vertical plane.  A loop will be 3 Gs during the initial pull and 1G or less over the top.
Comment: Ah, interesting, I didn't know the "1 G " reference came from an actual interview with the pilot.
Comment: So you all see where we are going with this, using aerodynamic load to compensate for negative gravity over the top (inverted) flight, either with elevator, thrust, or both.  I was fooled by the terminology "barrel roll".  It is a pitch and roll (now able to make Gs with el).  Bob Hoover was a genius.
Comment: @qqjkztd A jet like that with a thrust to weight >1 can "roll" at any G level it wants.  It can do it while in a ballistic arc, which can be sustained for 30 sec or more, and be 0 G through the entire roll.  That's not a barrel roll though, which is a centrifugal force maneuver.
Comment: Ballistic arc such as orbit, no?  Great stuff!  Thanks.
Comment: That's how they train astronauts.  A KC135 with the padded interior dives, pulls up into about a 30 deg climbs, pushes until G load is 0, and sustains that until the nose is pitched down in a dive, then pulls out.  2 Gs at the start and finish, with about 30 seconds of 0 G during the arc.  I can do it in my own plane but at 130 mph I can only sustain the 0 G state for about 3 seconds at the most, plus the engine quits momentarily and all the crap and dirt in the cockpit comes up and floats around your head.
Answer: By common terminology, when we speak of an "X G manuever" (say X=1 so a "1 G maneuver"), we mean that 1 G is the up-and-down acceleration indicated on the G-meter on the panel, and it also is the up-and-down acceleration (force per unit mass) acting to create stresses or strains on the aircraft's structure (and the pilot's body.)  In other words, it is the "felt" acceleration or force per unit mass, or at least the up-and-down component thereof, in the pilot's reference frame.  To get the ACTUAL up-and-down acceleration component (or force per unit mass) in the reference frame of the aircraft and pilot, we need to subtract the 1 G acceleration of gravity, or more precisely, the component of the the 1 G acceleration of gravity that acts in the up-and-down reference frame of the aircraft and pilot.  Why?  Because gravity exerts an equal acceleration (force per unit mass) on every molecule of the aircraft and pilot simultaneously and thus creates no stresses or strains within either, nor does it tend to accelerate the pilot toward or away from the aircraft and seat, so it is not a "felt" acceleration.
Two examples-- straight and level flight -- "felt" acceleration 1G, actual acceleration 0G. "Zero G" ballistic flight-- "felt" acceleration 0G, actual acceleration 1G downward (i.e. -1G).
So, in any maneuver that would commonly be described as a "1 G" maneuver, the G-force perceived by the pilot is +1 G, by definition.
Can a barrel roll be a "1 G" maneuver in this sense?  Sure, as the aircraft goes over the very top of the roll.  Can it be a "1G" maneuver in this sense from start to finish, including the initial pull-up and final round-out back to level flight?  No it cannot.  The barrel roll involves an arcing trajectory, and the G-load must be greater than 1-G during the initial pull-up and final round-out.
By the way, the "felt" acceleration as described above, is nothing more or less than the net aerodynamic force generated by the aircraft in whatever axis we are speaking of, or in all three axes if we want to be comprehensive.  Normally we are most interested in the forces acting in the up-down direction in the aircraft's reference frame-- that's what the G-meter on the panel indicates-- and this is overwhelmingly dominated by the lift force generated by the wings.   So when we speak of "feeling" 1 G (or "perceiving" 1 G), we are just saying that the wings are generating a net force equal to the mass of the (aircraft + contents) times the gravitational acceleration constant times two.
It may be sometimes a bit ambiguous as to whether the term "G-load" is being used to refer the TOTAL "felt" acceleration, or just the component that acts in the upward / downward direction in the pilot's reference frame.  Either way, if we label a maneuver a "1 G maneuver", the logical conclusion is the the pilot is perceiving a 1-G acceleration-- i.e. the aircraft is exerting a 1 G force (per unit mass) on the pilot.  Just as in straight and level flight.
Comment: meant to comment in another place.


Matlab Installation Issue for ubuntu14.04 with 32bits os

Question: I have tried number of times to install MATLAB from Ubuntu software center but it didn't get install and it didn't even display any error message. It just keep on showing that it is being install and it make my system slow. I have Ubuntu 14.04 [32bits], through Mathworks site there is no option for 32bit Linux OS. Please help!!
Answer: The MATLAB installation offered by Software Center does not actually install MATLAB, instead it installs a matlab-support package:

This package does not provide MATLAB. Instead, it configures an
   existing MATLAB installation to integrate more comfortably in
   a Debian installation.

Furthermore, as you have already deduced, Mathworks no longer support 32-bit Linux platforms: see the list of System Requirements and Supported Compilers Archive, according to which the last release to support 32-bit Linux platforms was 2012a

Note: Release 2012a was the last release of the 32-bit version of MATLAB for Linux. See the platform road map for more information.


Django Wagtail dynamic Menu's based on User and User Role

Question: Using Django-Wagtail and Wagtail Menu's. I want to build a system with the following types of characteristics.

I have a class of user (Vendor, Supplier)
Each created user would need to be one of these two classes.
Each class of user has different roles and the roles differ from class to class. e.g.
Vendor: finance, stock, admin
Supplier: finance, stock, admin, driver.

What I have done is create a class called UserType and both "Vendor" & "Supplier" inherit from this class. Then added a field to the User class that selects which type of user they are.
class UserType(model.Model):
    common fields.......

class Vendor(UserType):
    child_vendor_only_fields.....

class Supplier(UserType):
    child_supplier_only_fields.....

class User(AbstractUser):
    userVar = models.ForeignKey(UserType, on_delete=models.SET_NULL, null=True, blank=True)

I have also used the wagtail admin to create custom roles for each of these classes as described above.
Clearly what "Vendors" can create, read, update and delete varies from that of a "Supplier". And still within that what the finance role can do within the "Vendor" differs from what "Stock" can do.
How would I create a dynamic menu that displays different menu's for these permutations?
My initial thoughts were inspired by this. Simply adding a choicefield
USER_TYPE_CHOICES = (
('Vendor', 'Vendor'),
('Supplier', 'Suplier'))

class GenericPage(MenuPage):
    """
    This model will gain the fields, methods and `setting_panels` attribute
    from `MenuPage`, but `settings_panels` is being overridden to include
    other fields in the `Settings` tab.
    """
    availableTo = CharField(choices=USER_TYPE_CHOICES,)

    # 'menupage_panel' is a collapsible `MultiFieldPanel` with the important
    # fields already grouped together, making it easy to include in custom
    # panel definitions, like so:
    settings_panels = [
        FieldPanel('custom_settings_field_one'),
        menupage_panel
    ]

I have two questions:

Am I on the correct path for generating custom menu's for type of users? If so how would I then do the same for roles under type of users?

In terms of CRUD should I simply implement a check each time a user does a crud action whether or whether not they can commit that action pragmatically?
Answer: For CRUD, I'm not a fan of giving someone the option to do something then tell them that option isn't allowed after the fact. They might have spent half an hour creating/editing that page then find out they've wasted that time. Better to tell them on page load.
For user type, I'd just create those as roles that you add the users to. Then you just have a simple test for the user.groups to see what role they have.
You could easily develop a custom restricted panel for each of the panel types you need to restrict, easier if they're all FieldPanels. In the BoundPanel class you have access to the request object, so you can pull the user object from that at runtime and and decide what to do then.
The Panel.BoundPanel has a method is_shown(), so you can create a custom panel that inherits FieldPanel, override that method to test if the request user in an authorised list parameter and set true/false accordingly.
# restricted_field_panel.py
from wagtail.admin.panels import FieldPanel

class RestrictedFieldPanel(FieldPanel):
    def __init__(self, field_name, authorised_groups, **kwargs):
        self.field_name = field_name
        self.authorised_groups = authorised_groups if isinstance(authorised_groups, list) else [authorised_groups]
        super().__init__(self.field_name, **kwargs)

    def clone_kwargs(self):
        kwargs = super().clone_kwargs()
        kwargs.update(
            authorised_groups=self.authorised_groups
        )
        return kwargs

    class BoundPanel(FieldPanel.BoundPanel):
        def is_shown(self):
            show_field = super().is_shown()
            is_authorised = self.request.user.groups.get_queryset().filter(name__in=self.panel.authorised_groups).exists()
            return (show_field and is_authorised)

In the page model:
content_panels = Page.content_panels + [
    RestrictedFieldPanel('some_vendor_field', 'Vendors'),
    RestrictedFieldPanel('some_supplier_field', 'Suppliers'),
    ....
]

For the authorised groups, you might want to append a site admin role by default so that site admins will always see any restricted panel regardless.
Other panel types you'd need to inherit and do test wherever it's doing the rendering.


Dynamically disabling menu based on database query?

Question: So I'm not a programmer, but my friend is. He's trying to help me develop a web/phone app but we are stuck because I'm having trouble communicating to him an idea and he is having trouble understanding. One or both of us is a moron ;)  Part of the problem is that I don't even know where to search for the answer cuz I don't know the specific search terms...believe me I've tried...and I've searched stack overflow as well.  Here is the problem:
Short Question:
Websites (like hotel search) allow you to search for rooms by selecting checkboxes in certain categories (i.e. smoking/nonsmoking, stars, size of bed, near downtown, etc.). Certainly these sites are referencing a large database of hotels in a city.
How can you create a site so that as you check boxes (narrow your search), other options which are no longer available are dynamically "grayed out" or disabled on the fly so you cannot check those boxes.  So if I were to check 4 stars and that excluded all smoking rooms based on the database, then the option to check "smoking" would be disabled.
The key to this is that the site is querying a database as you click boxes, then based on the results of that query (which is presumably many rows of data (a subset)), it is analysing that subset of data to determine whether checkbox options should be on/off, then dynamically "graying out" specific options that are no longer available.  Once you got to only a single possible result, then the site would pop up the website for that hotel (or some other action).
What is this called?  Where can I get more information on this.  Any pointing toward the right direction would be tremendously appreciated.
Thanks so much in advance!
Roy
HERE IS AN EDIT TO ORIGINAL QUESTION...HERE IS AN EXAMPLE:

So here is my sample database.  Each Column (i.e. AA, AB, AC) represents a checkbox.  '1'= True, '0'= False, and '2'= Either.  Therefore, if you click checkbox AA, then only the top three rows would meet the criteria of AA=True.  So query would return the top three rows.  The '2's could be either True/False so since they don't affect outcome, those checkboxes should be disabled and only the checkboxes CA,CB, & CC should remain choosable.  If you then click checkbox CB, then result ZYX would be output.
Conceptually, How do you go from the initial click to the point where the database is queried and the results are used to dynamically change the menu.  People have suggested javascript but i am not looking for a language.  I am more looking for the concept.  I was thinking that the query would return a new "temp" array with just the top three rows.  Then each column of this "temp" array would be queried to see if it contained a '1' in any of the rows.  If it did, then that button would be turned "ON".  If it didn't then that button would be turned "OFF".  Is this confusing?  Am I asking for too much ;)
Answer: This sounds like javascript could help. For example, using jQuery, you can dynamically send queries to databases based on whatever you click on checkboxes, and then reload a particular section of the webpage. Javascript can also dynamically disable checkboxes.
Comment: hey wei, i think everything that i come upon talking about dynamic updating of menu choices points to javascript...i guess I'm not getting how you go from a simple query of your database based on a 'button press' to a refresh of the menu...conceptually.  i will post more info on my original question.


What's the correct transformation for Lambert Conformal Conic for Mexico?

Question: I have a shp archive without the .prj file. I don´t know the proyection of this shp, but I think it is in lambert conformal conic. Can anybody helpme to proyect this shp? i´ve tried to proyect it in wgs84 utm 16N and geografic wgs84, but i have no success. this shp is from Quintana Roo, México. I´m working in qgis
Comment: Check this answer http://gis.stackexchange.com/questions/69203/is-it-possible-to-change-crs-without-the-prj-file/69291#69291
Comment: In oder to reconize if your layer is in INEGI´s LCC the x coordinate must be greater than  2,500,000 meters (for the zone you are working on). If it is smaller than  1,000,000 meters the SRC must be UTM. In the answer cited above you will fin the parameters for INEGI´s CCL, and you have to include it as a User defined CRS.
Answer: Two Lambert conformal conic definitions for Mexico were recently added to the EPSG Geodetic Parameter registry. Both have the same projection parameters, but are based upon different geographic coordinate reference systems. The projection parameters are:
<code>central meridian / longitude of origin: -102.0
latitude of origin: +12.0
standard parallel 1: +17.5
standard parallel 2: +29.5
false easting: 2500000.0 m
false northing: 0.0 m
</code>
The two geographic coordinate reference systems are both ITRF-based and have transformations to WGS 84 with parameters equal to zeroes.
Note: I'm on the subcommittee that maintains the registry.
Comment: This is really good news when and how can I get more information about these EPSG codes, finally after many years this happens.
Comment: http://www.epsg-registry.org/ is the place to look for. But note that +towgs84 parametres are treated seperately by EPSG, and confusingly have their own EPSG-code.


No Ground on old dryer

Question: My mom went out and bought a super old dryer to replace one that busted. I'm trying to hook it up with 4 prong cord hut there is no green nut for the ground. Where does the ground go?
Comment: Model # of the dryer?
Comment: GE dde8508malwh
Comment: I looked at this thread several times but it looked like it had a grounding screw and the OP wanted to know, assuming the green thread was a ground, it you connect with the case of the dryer or if it was a neutral and goes with the neutral. I'm connecting the cord and my green wire is definitely a ground. My problem is the dryer in question doesn't have an obvious bold or screw for the ground.
Answer: A modern dryer should have a separate ground (which is bonded to the exposed metal case of the dryer) and neutral connection, with a removable jumper between them.
Unfortunately, I can't seem to find an installation manual for this model, just several copies of the Use & Care Manual. There are three possibilities:

The dryer has connections for 2 hots + neutral and no wiring at all for ground and the metal parts of the dryer are not connected to the neutral. You can test this with a multimeter by seeing if there is continuity between unpainted metal parts and the neutral connection. If there is no continuity (and you really truly have no ground connection on the dryer anywhere) then "a self tapping screw and secure the ground in the connection area be sure not to poke any other wires" is the right answer as it will provide a reasonable ground connection independent of the neutral connection.
The dryer has ground & neutral bonded together with a jumper. For any dryer made after 1996 (and possibly even a little older) there should be a jumper and by removing the jumper have ground independent of neutral. If you test with a multimeter and find continuity between the metal parts and neutral then if you can find and remove this neutral-ground jumper you can then connect ground to the case with a self-tapping screw and be safe.
The dryer has ground & neutral bonded together but no specific connection can be found. If this is the case then you have a 3-wire connection forced on you. If you were to connect a grounding wire to the metal case, you would effectively be bonding neutral & ground so that even though you are using a 4-wire connection, safety-wise it would be exactly the same - with the same dangers - as a 3-wire connection. If this turns out to be the case then I do NOT recommend this as (a) you are cheating well-established (> 20 years) safety standards and (b) likely have a VERY old dryer.

Bottom line: If you still can't find a jumper, check for continuity between case and neutral. If you don't have any continuity (check multiple locations to be sure) then ground to the case. If you do have continuity, get a different dryer. Used is OK, as long it isn't too old. Anything newer than 1996 should have a removable jumper so that you can connect it correctly.
Comment: You'll need to use a *fine pitch* self tapping screw (10-32) not a normal sheet metal screw.  (Garvin Industries makes them, ask for a [Garvin GSST](https://www.garvinindustries.com/electrical-junction-boxes/installation-accessories/grounding-wires-screws-and-clips/gsst) at an electrical supply house sometime...)
Comment: Will I need to completely remove the cord to test this? Seems like I would.
Answer: It will work with out the ground, but for the safety of the operator, you can ground it to the sheet metal of the dryer, get yourself a self tapping screw and secure the ground in the connection area be sure not to poke any other wires
Comment: Does a dryer of this vintage have an existing hole and screw for attaching the grounding conductor? Does it have a procedure for disconnecting the bond between the neutral and ground on the dryer connection block?
Comment: @Harper -- the problem with self-tappers is the thread pitch not the self-tapping functionality.  A 10-32 self-tapper is legal for grounding under the NEC, and [Garvin makes 'em (in green even!)](https://www.garvinindustries.com/electrical-junction-boxes/installation-accessories/grounding-wires-screws-and-clips/gsst)
Comment: So it doesn't matter where it goes as long as it goes through metal and doesn't interfere with the other wires?
Comment: There are several wholes where it looks like screws went before. The appears to have been for the carriage (if that's what it is called) that holds the terminal block. There 5 holes, 3 have screws in them. I don't see an area for neutral outside of the terminal block. It's my guess that the neutral screw was in the odd hole on one side of the terminal, but I can't be sure and didn't want mess something up.
Comment: Self tapping screws are not appropriate for ground connections, NEc specifically outlaws them.  If you can't find a hole threaded 10-32 or 8-32, try a plain hole, bolt and nut.

No Ground on old dryer


What's the song they are playing before Kaneki sees the news reports in season 2, episode 9?

Question: The track is played again at the end of the same episode when Kaneki is on the rooftop with Nishio and Tsukiyama.
Answer: The song is called Das zweite Kapitel, which, according to Google Translate, means "the second chapter" in German. It is track 26 from the first disc of Tokyo Ghoul Original Soundtrack.


3D-Print Addon - Zero Faces

Question: I wanted to get familiar with the 3D-Print add-on so I created that odd, blobby mesh which is just the default Blender cube, subdivided and then I applied some touch of 'Draw Sharp' and "Clay Strips' in Sculpting Mode. Easy.
When I run the 3D-Print add-on I get '41 Zero Faces' and I don't really understand why, everything looks OK to me.
Any Thoughts?
Answer: What I understood ... Zero faces are faces too small to keep such detail in print and would be degenerated (simplified) by printer in final result.
In reality ... Each printer is capable of some minimal step in print (resolution). If you will have an ornament detailed by small faces lower than degenerate value is set, than addon informs you those faces wouldn't participate in final print in such details and could be simplified by limit of printer step. Or it is just saying - too small to be noticed by printer, and topology can be simpler for given printer resolution.
If you scale model in edit mode, merge by distance or lower degeneration value in addon they're gone.
In your case nothing will happen if you ignore it.
Comment: just to mention, the threshold for the zero faces check is the value of 'Degenerated' and the default is 0.00010. It's measured in m² (square meters). 0.0001 m² is 1 cm² (=1cm x 1cm). Fairly large, I think.
Answer: Zero faces mean they are so close together the area equals zero.
Here's a video tutorial that may help explain the options of 3D Printing Tool Box.
Blender Mesh Fixing | 3D Printing Tool Box Explained
https://www.youtube.com/watch?v=0rgrLWFUjlk
<code>Time Stamps:
0:00 - The 3D Print Tool Box | Blender Mesh Analysis.
1:03 - How To Scale By Volume & Bounds.
2:40 - Non-Manifold Edge Explained.
3:35 - Bad Contig. Edges Explained.
4:20 - Intersect Face Explained.
5:34 - Zero Faces Explained.
6:19 - Zero Edges Explained.
7:18 - Non-Flat Faces Explained.
9:10 - Thin Faces Explained.
10:10 - Sharp Edge Explained.
11:30 - Overhang Face Explained.
12:15 - A Little Bug To Watchout For.
13:19 - Automatic Blender Mesh Fixing & Exporting.
14:15 - Mesh Design Things To Keep In Mind.
</code>
Comment: Please outline the relevant steps in your answers rather than just posting links. Link only answers are likely to be removed unless edited, as they are not useful to future visitors if the linked content goes down.

3D-Print Addon - Zero Faces


Script Error in webBrowser control WPF

Question:
When am work on webBrowser control using wpf Getting error like "script error" even i pasted screen shot here and even some jquery UI and css not working
Comment: We'll need more information on this one.
Comment: Possible duplicate of [WPF WebBrowser control - how to supress script errors?](http://stackoverflow.com/questions/6138199/wpf-webbrowser-control-how-to-supress-script-errors)
Comment: Xaml:
Comment: Had you tried my solution?
Answer: I faced this problem too. I need to create browser application which the web has lot of Jquery, JSON etc and webbrowser control does't work as expected (I'm using Windows 10 and Visual Studio 2015)
As solution, I use cefsharp.github.io which allow me to embed a full-featured standards-complaint web browser into C# or VB.NET project solution without hacking windows registry key. It based on Chromium Embedded Framework. It work like a charm!

Just grab nuget packages and create ChromiumWebBrowser class and you are ready to use it.
Answer: You have to change your WebBrowser rendering engine, by default it uses the oldest one.
In this link Microsoft describes how you can do it:
http://msdn.microsoft.com/en-us/library/ie/ee330730%28v=vs.85%29.aspx
And you can follow this good answer too.
Will the IE9 WebBrowser Control Support all of IE9's features, including SVG?
Pay attention that if you are running a 32 bit app on a 64bit system you must set this key instead
<code>[HKLM\SOFTWARE\Wow6432Node\Microsoft\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION]
</code>
I tried the site that fails in your screenshot and works well with this registry change from a WebBrowser.

Script Error in webBrowser control WPF


Reflection formula for spherical surface from Fermat's principle (Query)

Question:
The snip shows a part of the method shown by my teacher, to describe the reflection formula for spherical surface. However I do not understand how the relation of AB and BI (which I have highlighted) is coming. Please explain.
Comment: Related post by OP: http://physics.stackexchange.com/q/80713/2451
Comment: Perhaps by the [Law of Cosines](http://en.wikipedia.org/wiki/Law_of_cosines)?
Answer: The equations comes form the law of cosines, but we will see there is an error in the equations, as can be easily observed with dimensional analysis.
The law of cosines says that if you have a triangle with three vertices $A$, $B$ and $C$, and if the lengths of the sides connecting the vertices are $AB$, $BC$ and $CA$, and if the angles at each vertex are denoted by $\theta_A$, $\theta_B$, and $\theta_C$, then these quantities are related by $AB^2 = BC^2 + CA^2 - 2*BC*CA*\cos(\theta_{C})$.
If we apply this formula to the picture, except where $C$ from the formula is $R$ in the picture, we get $AB^2 = BR^2 + RA^2 - 2*BR*RA*\cos(\theta_{R})$. Now the length $BR$ is $r$, the radius of the spherical mirror. Also $\theta_{R}$ and $\theta$ make a straight line so $\theta_R = 180^\circ - \theta$. Plugging these in we get $AB^2 = r^2 + RA^2 - 2*r*RA*\cos(180^\circ - \theta)$. This matches the formula you have except the one you gave is incorrectly missing a factor of $r$ multiplying the cosine.
I will leave it as an exercise to find how to apply the law of cosines to the second triangle to produce the given equation. Think about which of the three angles you should use in the law of cosines. Also notice you will find a similar error in the second formula.
Answer: Well it seems that everyone who tries to teach geometrical optics, as far as ray tracing goes, seems to feel they have to create their own procedures, ignoring the fact that several hundred years of prior work, has established efficient ways to do it.  You state the problem is to establish the law of reflection from Fermat's principle.   So that can be established (from Fermat's principle as asked), without ANY reference whatsoever to the curvature of the surface; which is totally irrelevant to the problem, since the reflection takes place at the single point of ray incidence, on the surface.
So to move on from there to establish the relationship between your u, v, and r parameters, for your spherical mirror, useful closed form expressions can only be developed (for elementary studies), by assuming that the point B is very close to the axis, so that (theta) and the other two incident and reflected angles, are small enough so that the sin is equal to the angle (in radians).  This is the so-called "paraxial region."  Then NO trigonometry is required.  B can be described by its height (h) from the axis.
In formal ray tracing for optical design, there is no difference between reflection and refraction.   If reflection is required, and the incident ray is in a medium of index (n), then the reflected ray is in a medium of index (-n).  Distances following reflection are reversed in sign.
The usual sign convention for "left to right" tracing, is that distances to the left of the surface are negative; those to the right are positive.  If the center of curvature is to the left of the surface, then the surface radius is negative.
So in your diagram, u, v, and r, are ALL negative.  a common convention uses unprimed parameters for quantities before refraction  (reflection), and primed parameters, for those after refraction.
So your u, v, r would be l, l', r, and the indices would be n and n'.
Then the standard paraxial refraction formula is:-
<code>    n'/l' = n / l + (n'-n) / r
</code>
So for your spherical mirror case, we would put n = 1 and n' = -1 , giving:-
<code>    -1 / l' = 1 / l + (-1 -1) / r
</code>
or to put it in your variable names;
<code>    -1/v = 1/u + (-1-1)/r
</code>
I'll let you finish that off.
For imaging small objects of height (h) or (h') and with marginal rays at angles of (u) and (u'), it can be shown, that the quantity    (nhu) is invariant under all optical transformations.  It is known as the Lagrange Invariant.   The corresponding form outside the small angle paraxial region, says  NHsin(U) is invariant.   This is the optical sine theorem.
This formalism is NOT new.   It was first taught by A. E. Conrady in 1926, an is readily available today as a Dover Press paperback, in two volumes.   If you want to learn optical design; buy it.