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Posts posted by Sato

  1. Since the parachutes may be too heavy for each seat, why they don't provide each passenger with inflatable balloons? The airbags would be strapped one in the front and one in the back, front pack plus back pack, this wouldn't assure 100% survival of the victims, but at least it can soften the impact on the ground.


    I don't know how well balloons would do in the way of exploding jet fuel and speeding shrapnel.

  2. I don't have much experience with Java, but implementing such a thing shouldn't be so difficult. Just read through the image (it's 493 by 584 px), extract each pixel's RGB values, fill up a multidimensional array with those values accordingly, and pass it to whatever image display function you're using (with the data formatted in line with its standards).

  3. These look generally applicable: http://wdfw.wa.gov/fishing/shellfish/crab/identification.html,



    Published papers about specific crabs:

    http://www.seer.furg.br/atlantica/article/download/1526/667 (Ghost)

    http://museumvictoria.com.au/pages/4022/60_1_gilchrist.pdf (Hermit)

    http://www.scielo.br/pdf/rbzool/v19n4/v19n4a08.pdf (Hermit)

    http://www.swfwmd.state.fl.us/projects/mfl/reports/Chass_Appendices/Section_11.16.pdf (Blue)

    http://web.vims.edu/bridge/bluecrabworkshop2.pdf?svr=www (Blue)


    Those papers require a technical English reading level, but if your son is interested enough he will be able to look up terms and if he does not know already, recommend that he read the first sentence of and skims the body of Wikipedia pages for terms he doesn't know. Good on you for putting effort into assisting your son's explorations! :)


    If we're close to the sun, it's far more efficient to use solar power to supply energy to the satellite.


    For propulsion, it's not just a matter of power. You need a propellant, too. Photons don't carry much momentum, so there's a limit to how well you can propel a craft without some massive propellant to eject.


    I think that was brought up in his other thread, the use of solar sails maneuvered by radiation pressure.

  5. May I know why wireless power transmission via lasers is possible but not too efficient?


    There, I believe, is usually a 40+% loss when converting from electricity to laser output; only ~60-70% (maybe more with some recent advances) of the electricity used to pump a laser will end up being useful in actually causing the production of the laser beam. I knew someone who was able to reach more than a 70% conversion efficiency but as far as I know that's not been used/released outside yet. You could research laser physics and maybe you'll find a way to make some efficient laser / solar focusing device or something specifically for powering probes! :)

  6. Genecks asked "how could you tell conciousness was still happening" I will go a step further and ask if consciousness requires a body? Sight, sound, touch, taste, smell, etc define our world and as such define how our brains process information. What does a bodiless human consciousness think? It is hot or cold, hungry or full, does it feel sleepy, or etc? Do our brains require inputs to properly function?


    I expect that it's possible for a man to have full-body paralysis and numbness, a loss of auration, vision, gustation, olfaction, tactility, and appetite, and still the capacity think and even communicate (possibly through an EEG or something of the sort).

  7. Seismographs regularly detect and track ground shaking that is not normally detectable by people at the surface. While it is technically possible to send modulated acoustic signals through the earth I suspect the power requirements would be prohibitive. A downside might be disturbing certain wildlife that use extra low frequency to communicate, e.g. elephants. The US Navy experimented on-and-off with low frequency sonars in the oceans, but -by most accounts- stopped because the signals disoriented whales.


    Ah, alright, thank you very much!

  8. Hello,


    For anyone who has some familiarity with the generation and functionings of earth quakes and other such geological phenomena, is it possible (I'm sure it is, but how exactly does this work) to generate underground vibrations not large enough to cause any notice above ground, but enough such that the vibrations can be tracked / received like signals. How efficient is this process of generating these? Would it be possible to sent communications through such a system, and how feasible would this be? What might be the downsides, and what special use could this have?


    Thank you,


  9. Session id stored in cookie should be id to database entry in currently open session table.

    Database record should store IP address of owner of session,

    and code should check whether db IP matches with what is clients IP.


    This will make sure that even if somebody intercept cookie value, he/she won't be able to use it, because their IP will be different than original client that opened session.

    As long as they didn't intercept whole client network and are able to show up as the same IP..


    This causes unneeded trouble for anyone on a network with a dynamic IP address and anyone who accesses the service on a phone, laptop, or tablet which moves around and connects to different networks, all of which will constantly log the user out. It's safest and best-practice to actually secure and sanitize all I/O than to use a back-of-the-hammer work around like that; besides the point mentioned in my first remark, even if one can't access the session, they would still be able to execute malicious scripts and ergo interact with the website on the target's browser, and, most importantly, an IP address can be spoofed by directly modifying the request packets, rendering that validation useless.

  10. Yes, a cookie can be edited through a browser via javascript. This is only a concern if the attacker can get access to their target's cookie, which should be securely stored in your database and on user's browser. Make sure to sanitize all your input so that nobody can execute database commands, which I think can be done using the mysql_real_escape_string() function in PHP (if you're using a MySQL db). Also, namely because if someone has access to your database they probably won't be bothered to forge their target's cookie, your primary concern for this matter would probably be an XSS attack. This is when you allow a user to provide some information or data and it is displayed back on some part of the website; if you don't sanitize the output (with htmlentities() I believe), the user will be able to input HTML and javascripts that when displayed on the site, such as in the username, will be interpreted as HTML/JS and ran by viewers' browsers. So, in the context of session forgery, one could deliver a script which accesses a user's cookie and sends a request to their own server adding it to a log file or something of the sort. The attacker can then go onto your website and replace their session cookie with what was sent to their log, and access the site as someone else. Also remember to sanitize the user's cookie before you check it against what's in the database, as someone could edit their cookie and replace it with a MySQL command.

  11. Whahahaha Whahahahahahahaha nope, lol that can't be true because:


    1. There is black people and asian ect all with different size or color skin and nose and the shapes of the face ect, and I'm sure, that just as much too, since brain wired, a black boy is most attracted to a black girl....that's why they always end up with the same look


    2. A girl and a boy show evidence of brain wired definitely, attracted to the opposite gender only, girl to boy and boy to girl.


    3. I know what I said is true myself actually because the most attractive look looks like myself but not exactly, and I'm also attracted to myself since am normal with long hair and fringe, so there mustttt...be something in the brain....that after creating you, makes you attracted to those genes/look, and you knowww the look, as when you see, you know, if u attracted, and the brain changes the attraction a bit to female anf that's why you like yourself, but not the jem, well it is, but the opposite gender perfect match is what you really want as much or I think more and is a jem or more of one even more attractive...




    1) No, interracial attraction is actually very common, that from whites to blacks to asians and vice-versa. The reason there is not as much interracial mating as there might be is that there are generally, especially where I live, communities that can be distinguished by something like a 99% black or white population, and this through years forms a subtle discomfort with other races relative to those who surround you. There is also a residual population of people who were around and comfortable during more... racist times. And, if our brains are hardwired to be attracted to any race, it's different races rather than our own: http://www.dailymail.co.uk/sciencetech/article-2099449/Are-human-beings-hard-wired-different-races-attractive-Study-finds-white-people-rate-white-partners-SECOND.html.


    2) No, bad, wrong, no, stop right there. Males can be and to an extent are just as attracted to other males as they are to females, and such is true with females as well. This grounds from work done by Freud and Kinsey and has been studied to this day (http://en.wikipedia.org/wiki/Innate_bisexuality), noticing that as homosexuality and bisexuality become more acceptable in society, and children don't hear the idea getting shunned as much, that the population of homosexuals is increasing drastically. This is no coincidence; it is social freedom allowing humans to express their honest sexualities.


    3) No, again, it's more likely that you either resemble those who were exposed to you in media and social contexts (either implicitly or explicitly) as attractive during your younger years, or you're just pompous. I generally find people attractive based on my interaction with them, and as such have even been attracted to those not considered attractive under your definition, both male and female, breaking your premise down.

  12. JS does follow a standard set by ECMA-262 specification and ISO/IEC 16262, that said, having read the spec, it is very strange in a lot of places. The original ECMA script spec literally stated that semicolons were not necessary to terminate the lines, but can be used as such, and that the actual point/use of the semicolon will be determined later... Tis a strange language




    Ok, i would not do my job if i did not pick on this statement, but a compiler actually does not generate assembly. C/C++ compiler parses the code into a parse tree, checks syntax and common mistakes, consistency, etc, in the process, fills in constants, drops code in paths that can not be reached, runs one or a number of optimization cycles (some optimizations can be done in parallel, others have to be done serially), converts the parse tree into opcode for the linker, and passes the code over to the linker (usually there is an optimization cycle here too), which will eventually call the assembler which will convert the opcode into assembly, and then also usually run an optimization cycle.


    The process of compilation is generally considered to encapsulate assembly, while it also involves preprocessing, linking, as well as another more specific process of compiling that generates the object code, and I'm also pretty sure that the GCC package contains an assembler too. Anyway, that's besides the point; the intention was to refer to a language through which he could interact with the computer at a lower level, rather than describe the compiling process, which, unless you're suggesting that writing binary object files and manually linking is a good low-level alternative to assembly, is not very relevant to the conversation.

  13. There's theoretical CS which heavily involves pure mathematics, but seeing as you're interested in applied mathematics and had considered majoring in physics I'd think that, in terms of your interests, computer engineering is the way to go. And in regards to the low job prospects you hear about, more and more companies are starting in and transitioning, both their products and infrastructure, to digital media and so are heavily hiring CS/IT majors as programmers, sysadmins, and web developers. Besides that there's a heap of large companies hiring specifically for computer hardware engineering such as Intel, Microsoft, Google, etc and well as academia and other smaller ventures that you'll discover when looking for a job, and along with these you'll also find what exactly you should do to up your chances at getting hired at these companies (Quora.com often yields nice results about such questions).


    I say go for computer engineering.

  14. Hello,


    Inputting the expression "Simplify [//math:(a-b)*(sum (a^(n-i) * b^(i-1)), i=1 to n)//]" into WolframAlpha yields:

    a^n + b^n for a != b


    (as expected)


    How did you derive these results? What was your thought process?

  15. What I meant was the numbers from one part of mathematics can represented in geometric form(picture form), whether or not it was intended for geometry. However, somethings(such as complex numbers) can only be represented with geometries that are outside the norm.


    Eh, I think that while it's true that you can represent algebras and algebraic relations geometrically, and geometric examples and proofs look a lot more pretty and intuitive than otherwise, those are only specific representations while things like groups (and other algebraic/mathematical structures) themselves are general and cannot be wholly considered geometrically.

  16. If you find the JS syntax difficult to follow, you probably won't enjoy the much more complicated C++ syntax, but all of those languages including Java have that same C-derived curly-bracket & semicolon syntax that you'll have to put time into grasping to learn any of them.


    C++ has very high OOP capabilities.


    If you want to be as close to the processor as you can be, then start writing assembly (x86 probably, for you) which is what the C/C++ is actually compiled into. Don't really do that, but I think you might be interested in looking into/playing around with assembly in concurrence with learning whatever language to understand how the processor is actually instructed and analyse or even optimize your own programs directly in asm.

  17. The 00's? I don't think modern electromagnetism was even developed until the 1800's, and that's when changing magnetic fields began being used to cause electrical flow. Even late that century Tesla developed a system that could power lamps remotely.


    Wireless power transfer can also be done via lasers and receivers in a similar manner to solar radiation / panels. Though the solar power hitting the ground isn't strong enough (esp. under the atmosphere), a directed laser could power anything from far away, even charging cars considering that the power is being transferred at c. But, the power density required for such things would probably yield ionizing radiation which can burn things and cause cancer and the conversion from electricity to laser back to electricity is very inefficient where losses can be <40%.

  18. Yes, they all go to hell. In fact, because there is more than one religion that considers all non-believers fated to go to hell, everyone goes to hell.


    Also, considering that heaven isn't real, there's no point in speculating about what they'd wear.

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