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  • Web app - Biometric system connection

    - by DMin
    Hi, I will be developing an application for a club where they will have visitors use biometric systems(finger print) or magnetic cards to mark their attendance. This application is planned as a web app, made using PHP/MySQL/Javascript. It does a lot of other things as well. What I wanted to find out is how is the interface between Biometric/Megnetic Card systems to a web app done? I've never worked on this and am hoping if someone who has experience with this can throw some light on this as to how this could be accomplished. Any pointers will be appreciated. (I'm afraid there's got to be some form of application installed on a pc that would interface with the hardware and probably makes calls to the web app. But, if there was a way to connect it to the web app directly, then the app would be easy to deploy to any location with minimal installation.) Thanks! :)

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  • MacBook Pro 13" Install DVD Wont Start

    - by Belliez
    Hi, Excuse such a basic question... I am a Laptop Fixer and deal with Windows based laptops only but very recently took in a 13" MacBook Pro for a re-install of the OS (easy I thought!) I inserted the Install DVD, held the C button and turn on. I could hear the disk spinning up and after about a min the DVD is ejected. There are a few scratches on the DVD but should be ok as not that deep. However, Windows Vista was installed (it failed to install properly hence the re-install of Mac OS). Should I wipe clean and format the hard disk first? Could this be the reason the DVD is ejected? Any advice would be gratefully accepted? p.s. never held a MacBook Pro before... first impressions, wow... alu casing and massive touch pad... and the magnetic power socket.... so impressed and it doesn't even work!

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  • How can I get Windows 8 to automatically disable touch when I am using my Wacom pen and turn it back on when I am not

    - by Robert
    I have an HP convertible tablet computer which I just upgraded to Windows 8. The problem (which existed under Windows 7 as well) is that this tablet has both a capacitive touch screen (with multi-touch) AND a wacom-type tablet built in to the screen that works using electro-magnetic resonance with the provided stylus. My Use Case: Most of the time I am happy using my fingers and the touch interface for navigation and whatnot. However, when I want to get down to serious note-taking/drawing, I want to use the wacom functionality. The problem is that any comfortable writing position has me resting my arm/hand on the screen, which activates the touch technology (despite supposed palm-detection algorithms) and completely screws up my input paradigm. My Ideal Solution: Ideallly, since wacom technology senses when the pen is "close" to the screen, I would love to have touch be automatically disabled whenever the wacom pen is detected, and turned back on when it is out of range. this would allow me to seamless switch between the two input methods, and since I NEVER want to use both at once would work perfectly for me. An acceptable alternative: As a next best option, It would be great to be able to turn off the touch functionality (leaving the wacom in place) whenever I entered specific apps (e.g. OneNote, Photoshop, Gimp, Pencil, etc.) and then have it turn back on when I left that app.... As a worst case at least lets me use my PC option: If I could create a shortcut (tile or otherwise) that flips the touch on and off without going all the way through the nested computer settings, that would be better than nothing. Thanks in advance for the help with 1 or more of the above.

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  • What diagnostics are safe to run on an SSD drive?

    - by Peter Mounce
    I have a MacBook Pro (late 2010) with a Crucial RealSSD 256Gb in it; 60Gb is given to the Windows 7 x64 BootCamp partition. I have a USB-attached 500Gb drive for (most) data. In the last day or so, I've had a BSOD and several OS freezes (both Mac OSX 10.6.6 and Win7). The system in both cases will boot fine (at the moment!) and then run things fine, then some time later a program will stop responding, followed shortly thereafter by the system as a whole, forcing a reboot. This smacks to me of a storage problem. Given that I have an SSD and not a regular magnetic HDD, what are my next steps, in both OS'? I haven't seen anything pertinent in Windows' event-log. I'm not sure of the equivalent place to look in OSX; it's never given me issue to find out. What are my options for attempting to save my data from the SSD to another drive, given that after some small amount of time (eg half an hour), the OS stops responding? What are the recommended next steps?

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  • Clever memory usage through the years

    - by Ben Emmett
    A friend and I were recently talking about the really clever tricks people have used to get the most out of memory. I thought I’d share my favorites, and would love to hear yours too! Interleaving on drum memory Back in the ye olde days before I’d been born (we’re talking the 50s / 60s here), working memory commonly took the form of rotating magnetic drums. These would spin at a constant speed, and a fixed head would read from memory when the correct part of the drum passed it by, a bit like a primitive platter disk. Because each revolution took a few milliseconds, programmers took to manually arranging information non-sequentially on the drum, timing when an instruction or memory address would need to be accessed, then spacing information accordingly around the edge of the drum, thus reducing the access delay. Similar techniques were still used on hard disks and floppy disks into the 90s, but have become irrelevant with modern disk technologies. The Hashlife algorithm Conway’s Game of Life has attracted numerous implementations over the years, but Bill Gosper’s Hashlife algorithm is particularly impressive. Taking advantage of the repetitive nature of many cellular automata, it uses a quadtree structure to store the hashes of pieces of the overall grid. Over time there are fewer and fewer new structures which need to be evaluated, so it starts to run faster with larger grids, drastically outperforming other algorithms both in terms of speed and the size of grid which can be simulated. The actual amount of memory used is huge, but it’s used in a clever way, so makes the list . Elite’s procedural generation Ok, so this isn’t exactly a memory optimization – more a storage optimization – but it gets an honorable mention anyway. When writing Elite, David Braben and Ian Bell wanted to build a rich world which gamers could explore, but their 22K memory was something of a limitation (for comparison that’s about the size of my avatar picture at the top of this page). They procedurally generated all the characteristics of the 2048 planets in their virtual universe, including the names, which were stitched together using a lookup table of parts of names. In fact the original plans were for 2^52 planets, but it was decided that that was probably too many. Oh, and they did that all in assembly language. Other games of the time used similar techniques too – The Sentinel’s landscape generation algorithm being another example. Modern Garbage Collectors Garbage collection in managed languages like Java and .NET ensures that most of the time, developers stop needing to care about how they use and clean up memory as the garbage collector handles it automatically. Achieving this without killing performance is a near-miraculous feet of software engineering. Much like when learning chemistry, you find that every time you think you understand how the garbage collector works, it turns out to be a mere simplification; that there are yet more complexities and heuristics to help it run efficiently. Of course introducing memory problems is still possible (and there are tools like our memory profiler to help if that happens to you) but they’re much, much rarer. A cautionary note In the examples above, there were good and well understood reasons for the optimizations, but cunningly optimized code has usually had to trade away readability and maintainability to achieve its gains. Trying to optimize memory usage without being pretty confident that there’s actually a problem is doing it wrong. So what have I missed? Tell me about the ingenious (or stupid) tricks you’ve seen people use. Ben

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  • Retrofit Certification

    - by Bill Evjen
    Impact of Regulations on Cabin Systems Installation John Courtright, Structural Integrity Engineering There are “heightened” FAA attention to technical issues related to IFE and Wi-Fi Systems Installations The Aging Aircraft Safety Rule – EWIS & Damage Tolerance Analysis The Challenge: Maximize Flight Safety While Minimizing Costs Issue Papers & Testing, Testing, Testing The role of Airworthiness Directives (ADs) on the design of many IFE systems and all antenna systems. Goal is safety AND cost-effective maintenance intervals and inspection techniques The STC Process Briefly Stated Type Certifications (TC) Supplemental Type Certifications (STC) The STC Process Project Specific Certification Plan (PSCP) Managed by FAA Aircraft Certification Office (ACO) Type of Project (Electrical/Mechanical Systems or Structural) Specific Type of Aircraft Being Modified Schedule Design & Installation Location What does the STC Plan (PSCP) Cover? System Description – What does the system do? System qualification – Are the components qualified? Certification requirements – What FARs are applicable? Installation detail – what is being modified? Prototype installation – What is new? Functional hazard Assessment (FHA) – is it safe? EZAP-EWIS Requirements – Any aging aircraft issues? Certification Data – How is compliance achieved? Delegation and FAA involvement – Who is doing the work? Proposed certification schedule – When is the installation? Certification documentation – What the FAA Expects to see Cabin Systems Certification Concerns In addition to meeting the requirements for DO-160, Cabin System Certification needs to address issues related to: Power management: Generally, IFE and Wi-Fi Systems are classified as “Non-Essential Equipment” from a certification viewpoint. Connected to “non-essential” power buses Must be able to shed IFE & Wi-Fi Systems in a smoke/fire event or Other electrical emergency (FAA Policy 00-111-160) FAA is more relaxed with testing wi-fi. It used to be that you had to have 150 seats with laptops running wi-fi, but now it is down to around 50. Aging aircraft concerns – electrical and structural Issue papers addressing technical concerns involving: “Structural Certification Criteria for Large Antenna Installations” Antenna “Vibration/Buffeting Compliance Criteria” DO-160 : Environmental Test Procedures DO 160 – “Environmental Conditions and Test Procedures for Airborne Equipment”, Issued by RTCA Provides guidance to equipment manufacturers as to testing requirements Temperature: –40C to +55C Vibration and Shock Contaminant susceptibility – fluids and dust Electro-magnetic Interference Cabin systems are generally classified as “non-essential” Swissair 111 crashed (in part) due to non-standard wiring practices. EWIS Design Implications Installation design must take EWIS Requirements into account. This generally means: Aircraft surveys are needed to identify proper wire routing Ensure existing wiring diagrams are correct Identify primary/Secondary/Tertiary bus locations Verify proper separation of wire bundles exist Required separation from fuel quantity indicator system (FQIS) to prevent fuel tang ignition Enhanced Zonal Analysis Procedure (EZAP) Performed EZAP was developed by the Aging Transport Systems Rulemaking Advisory Committee (ATSRAC) EZAP is the method for analyzing airplane zones with an emphasis on evaluating wiring systems and the existence of combustibles  in the cabin. Certification Considerations for Wi-Fi Systems Electrical – All existing DO 160 testing required Issue papers required Onboard EMI testing – any interference with aircraft systems when multiple wi-fi users are logged on? Vibration/Buffeting compliance criteria – what is the effect of the antenna on aircraft flight characteristics? Structural certification criteria – what are the stress loads on the aircraft at the antenna location and what is the impact on maintenance inspection criteria for the airline? Damage tolerance analysis required Goal – minimize maintenance inspection intervals

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  • Best cubicle toys for programming

    - by dlamblin
    I need some employee/co-worker Christmas gift ideas. Do you have any good cubicle toys that help you to do any of: think about programming problems solve programming problems by representing common abstractions can be directly programmed can interface with a PC based IDE to be programmed. it may present problems that can be solved, to kick start problem solving. Disallowed items are: reference material in book, pamphlet, poster or cheat-sheet form, even if it has kick ass pop-cultural references. edibles. [discuss separately] things that need their own lab-space and/or extensive tools to be worked with. So yes, Lego Mindstorms come to mind, but they aren't cubicle toys because they cost more than cubicle toys would, and they have too many losable parts. comments on the answers so far: The 20 Questions game sounds quite neat as it could get you thinking; The bean balls could be used as tokens in a problem, so I can see that working. The magnetic toys like ball of whacks or the ball-and-stick ones present hands on fun of a structural nature... now can there be a similar hands on fun toy that aids in representing a solution to a problem? The Gui Mags clearly could, but they're quite utility oriented. The AVR Butterfly is less of a toy but definitely priced attractively, cheaper and more responsive than a basic stamp. I'm not going to pick an answer; there's several great suggestions here. Thank you.

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  • Keyboard hook return different symbols from card reader depends whther my app in focus or not

    - by user363868
    I code WinForm application where one of the input is magnetic stripe card reader (CR). I am using code George Mamaladze's article Processing Global Mouse and Keyboard Hooks in C# on codeproject.com to listen keyboard (USB card reader acts same way as keyboard) and I have weird situation. One card reader CR1 (Unitech MS240-2UG) produces keystroke which I intercept on KeyPress event analyze that I intercept certain patter like %ABCD-6EFJHI? and trigger some logic. Analysis required because user can type something else into application or in another application meanwhile my app is open When I use another card reader CR2 (IdTech IDBM-334133) keystroke intercepted by hook started from number 5 instead of % (It is actually same key on keyboard). Since it is starting sentinel it is very important for me to have ability recognize input from card reader. Moreover if my app running in background and I have focus on Notepad when I swipe card string %ABCD-6EFJHI? appears in Notepad and same way, with proper starting character) intercepted by keyboard hook. If swiped when focus on Form it is 5ABCD-6EFJHI? User who tried app with another card reader has same result as me with CR2. Only CR1 works for me as expected I was looking into Device manager of Windows and both devices use same HID driver supplied by MS. I checked devices though respective software from CR makers and starting and ending sentinels set to % and ? respective on both. I would appreciate and ideas and thoughts as I hit the wall myself Thank you

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  • Using ARIMA to model and forecast stock prices using user-friendly stats program

    - by Brian
    Hi people, Can anyone please offer some insight into this for me? I'm coming from a functional magnetic resonance imaging research background where I analyzed a lot of time series data, and I'd like to analyze the time series of stock prices (or returns) by: 1) modeling a successful stock in a particular market sector and then cross-correlating the time series of this historically successful stock with that of other newer stocks to look for significant relationships; 2) model a stock's price time series and use forecasting (e.g., exponential smoothing) to predict future values of it. I'd like to use non-linear modeling methods (ARIMA and ARCH) to do this. Several questions: How often do ARIMA and ARCH modeling methods (given that the individual who implements them does so accurately) actually fit the stock time series data they target, and what is the optimal fit I can expect? Is the extent to which this model fits the data commensurate with the extent to which it predicts this stock time series' future values? Rather than randomly selecting stocks to compare or model, if profit is my goal, what is an efficient approach, if any, to selecting the stocks I'm going to analyze? Which stats program is the most user-friendly for this? Any thoughts on this would be great and would go a long way for me. Thanks, Brian

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  • Need to calculate rotation-vector from Sensor.TYPE_ORIENTATION data

    - by Sponge
    I need to calculate a rotation vector out of the data i get from Sensor.TYPE_ORIENTATION. The sensor data is defined like this: the values have to be recalculated to become a correct 3d position: values[0]: Azimuth, angle between the magnetic north direction and the Y axis, around the Z axis (0 to 359). 0=North, 90=East, 180=South, 270=West values[1]: Pitch, rotation around X axis (-180 to 180), with positive values when the z-axis moves toward the y-axis. values[2]: Roll, rotation around Y axis (-90 to 90), with positive values when the x-axis moves away from the z-axis I need all three values like the Z axis value (from 0 to 360 degree). I tried a lot but cant figure out how to do this :/ i also tried to use Sensor.TYPE_ACCELEROMETER and Sensor.TYPE_MAGNETIC_FIELD to calculate this 3d vector on my own. here is the code: final float[] inR = new float[16]; // load inR matrix from current sensor data: SensorManager.getRotationMatrix(inR, null, gravityValues, geomagneticValues); float[] orientation = new float[3]; SensorManager.getOrientation(inR, orientation); mapMagAndAcclDataToVector(orientation); //here i do some *360 stuff orientetionChanged(orientation); //then the correct values are passed (in theorie) But this didn't work and i think it is much to complicated. So i bet there is a simple solution how to recalc the values of ensor.TYPE_ORIENTATION to make them a 3d rotation vector, but i just dont know how to do it. If you know the answer please tell me.

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  • Accelerometer gravity components

    - by Dvd
    Hi, I know this question is definitely solved somewhere many times already, please enlighten me if you know of their existence, thanks. Quick rundown: I want to compute from a 3 axis accelerometer the gravity component on each of these 3 axes. I have used 2 axes free body diagrams to work out the accelerometer's gravity component in the world X-Z, Y-Z and X-Y axes. But the solution seems slightly off, it's acceptable for extreme cases when only 1 accelerometer axis is exposed to gravity, but for a pitch and roll of both 45 degrees, the combined total magnitude is greater than gravity (obtained by Xa^2+Ya^2+Za^2=g^2; Xa, Ya and Za are accelerometer readings in its X, Y and Z axis). More detail: The device is a Nexus One, and have a magnetic field sensor for azimuth, pitch and roll in addition to the 3-axis accelerometer. In the world's axis (with Z in the same direction as gravity, and either X or Y points to the north pole, don't think this matters much?), I assumed my device has a pitch (P) on the Y-Z axis, and a roll (R) on the X-Z axis. With that I used simple trig to get: Sin(R)=Ax/Gxz Cos(R)=Az/Gxz Tan(R)=Ax/Az There is another set for pitch, P. Now I defined gravity to have 3 components in the world's axis, a Gxz that is measurable only in the X-Z axis, a Gyz for Y-Z, and a Gxy for X-Y axis. Gxz^2+Gyz^2+Gxy^2=2*G^2 the 2G is because gravity is effectively included twice in this definition. Oh and the X-Y axis produce something more exotic... I'll explain if required later. From these equations I obtained a formula for Az, and removed the tan operations because I don't know how to handle tan90 calculations (it's infinity?). So my question is, anyone know whether I did this right/wrong or able to point me to the right direction? Thanks! Dvd

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  • Are Chromebooks the New Netbooks, and What Does That Mean?

    - by Chris Hoffman
    Netbooks — small, cheap, slow laptops — were once very popular. They fell out of favor — people bought them because they seemed cheap and portable, but the actual experience was lackluster. Most netbooks now sit unused. Windows netbooks have vanished from stores today, but there’s a new super-cheap laptop — the Chromebook. Chromebook sales numbers are impressive, but their usage statistics tell a different story. Are Chromebooks just the new netbook? The Problem With Netbooks Netbooks seemed appealing, especially in an age before tablets and lightweight ultrabooks. You could buy a netbook for $200 or so and have a portable device that let you get on the Internet. The name “netbook” spelled that out — it was a portable device for getting on the ‘net. They weren’t really that great. The original netbook was a lightweight Asus Eee PC that ran Linux alone and had a small amount of fast flash storage. Netbooks eventually ran heavier Windows XP operating systems — Windows Vista was out, but it was just too bloated to run on netbooks. Manufacturers added slow magnetic hard drives, bloatware, and even DVD drives! They couldn’t run most Windows software very well. The build quality was poor and their keyboards were tiny and cramped. People liked the idea of a lightweight device that let them get on the Internet and loved the cheap price, but the actual experience wasn’t great. Chromebook Sales Chromebook sales numbers seem surprisingly high. NPD reported that Chromebooks were 21% of all notebooks sold in the US in 2013. If you combine laptop and tablet sales into a single statistic, Chromebooks were 9.6% of all those devices sold. That’s 2/3 as many Chromebooks sold as iPads in the US! Of Amazon’s best-selling laptop computers, two of the top three are Chromebooks. These definitely look like successful products. Unlike netbooks, Chromebooks are taking off in a big way in the education market. Many schools are buying Chromebooks for their students instead of more expensive Windows laptops. They’re easier to manage and lock down than Windows laptops, but — more importantly for cash-strapped schools — they’re very cheap. Netbooks never had this sort of momentum in schools. Chromebook Usage Statistics Here’s where the rosy picture of Chromebooks starts to become more realistic. StatCounter’s browser usage statistics show how widely used different operating systems are. For example, Windows 7 has the highest share with 35.71% of web activity in April, 2014. The chart doesn’t even show Chrome OS at all, although there is an “Other” number near the bottom. Click the Download Data link to download a CSV file and we can view more detailed information. Chrome OS only accounted for 0.38% of web usage in April, 2014. Desktop Linux, which people often shrug at, accounted for 1.52% in the same month. To its credit, Chrome OS usage has increased. Chromebooks were widely mocked back in November, 2013 when the sales numbers came out. After all, they only accounted for 0.11% of web usage globally in November, 2013! But Chrome OS numbers have been improving: Nov, 2013: 0.11% Dec, 2013: 0.22% Jan, 2014: 0.31% Feb, 2014: 0.35% Mar, 2014: 0.36% Apr, 2014: 0.38% Chrome OS is climbing, but it’s definitely still in the “Other” category. It isn’t as high as we’d expect to see it with those types of sales numbers. Chromebooks vs. Netbooks Chromebooks are more limited devices than traditional PCs. You can do quite a few things, but you have to do it all using Chrome or Chrome apps. Most people won’t be enabling developer mode and installing a Linux desktop. You don’t have access to the powerful desktop software available for Windows and even Mac OS X. On the other hand, these Chromebooks are less compromised than netbooks in many ways. They come with a lightweight operating system designed for portable, mobile devices. They don’t come packed with any bloatware, like the bloatware you’ll find on competing Windows PCs and the original netbooks. They’re cheaper because the manufacturer doesn’t have to pay for a Windows license. There’s no need for antivirus software weighing the operating system down. They’re larger than the original netbooks, with many of them being 11.6-inches instead of the original 8-inch bodies many older netbooks came with. They have larger, more comfortable keyboards and fast solid-state storage. Really, Chromebooks are what netbooks wanted to be. People didn’t buy netbooks to use typical Windows software — they just wanted a lightweight PC. Of course, for many people, the real successor to netbooks is tablets. If all you want is a portable device to throw in a bag so you can get online, maybe a tablet is better. Where Does This Leave Chromebooks? So, are Chromebooks the new netbooks? It’s a bit early to answer that question. Chromebooks are definitely not out of the competition — their sales look good and their usage share is increasing. On the other hand, Chrome OS is still pretty far behind. They’re not catching fire like tablets did. Maybe netbooks were just before their time and Chromebooks were what they were always meant to be. Just as Microsoft’s Windows XP tablets failed, Windows XP netbooks also failed. Tablets took off with a more refined operating system on better hardware years later. “Netbooks” — or Chromebooks — are now taking off with a more purpose-built operating system on better hardware, too. It’s hard to count Chromebooks out because they provide a much better experience than netbooks ever did. If you’re one of the people who wants to use old Windows desktop apps on your portable laptop, you may think netbooks were better — but most people don’t want that. But maybe people either want a full desktop PC experience or a full mobile tablet experience. Is there a place for a laptop with a keyboard that can only view websites? We’ll have to wait and see. Image Credit: Kevin Jarret on Flickr, Clive Darra on Flickr, Sean Freese on Flickr

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  • eXML-PARSER output contains unwanted hash references

    - by seaworthy
    So I wrote a parser routine to take one xml file and reparse into another one. This code I later modified to split a large xml file into many small xml files. I am having a problem with an output. Parsing works fine the only thing output also includes unwanted strings like HASH(0x19f9b58), I am not sure why and need set of friendly eyes. use Encode; use XML::Parser; my $parser = XML::Parser->new( Handlers => {Start => \&handle_elem_start, End => \&handle_elem_end,Char => \&handle_char_data,}); my $record; my $file = shift @ARGV; if( $file ) {$parser->parsefile( $file );} exit; sub handle_elem_start { my( $expat, $name, %atts ) = @_; if ($name eq 'articles'){$file="_data.xml";unlink($file);} $record .= "<"; $record .= "$name"; foreach my $key (keys %atts){$record .= " $key=\"$atts{$key}\"";} $record .= ">"; } sub handle_char_data { my( $expat, $text ) = @_; $text = decode_utf8( $text ); $record .= "$text"; } sub handle_elem_end { my( $expat, $name ) = @_; $record .= "</$name>"; if( $name eq 'article' ) { open (MYFILE, '>>'.$file); print MYFILE $record; close (MYFILE); print $record; $record = {}; } return unless( $name eq 'article' ); } Sample output: ... </article>HASH(0x19f9b40) <article doi="10.1103/PhysRevSeriesI.9.304"> <journal short="Phys. Rev. (Series I)" jcode="PRI">Physical Review (Series I)</journal> <volume>9</volume> <issue printdate="1899-11-00">5</issue> <fpage>304</fpage> <lpage>309</lpage> <seqno>1</seqno> <price></price><tocsec>Articles</tocsec> <arttype type="article"></arttype><doi>10.1103/PhysRevSeriesI.9.304</doi> <title>An Investigation of the Magnetic Qualities of Building Brick</title> <authgrp> <author><givenname>O.</givenname><middlename>A.</middlename><surname>Gage</surname></author> <author><givenname>H.</givenname><middlename>E.</middlename><surname>Lawrence</surname></author> </authgrp> <cpyrt> <cpyrtdate date="1899"></cpyrtdate><cpyrtholder>The American Physical Society</cpyrtholder> </cpyrt> </article>HASH(0x19f9b58) ... HASH strings are not wanted, please advise.

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  • Longitudinal Redundancy Check fails

    - by PaulH
    I have an application that decodes data from a magnetic stripe reader. But, I'm having difficulty getting my calculated LRC check byte to match the one on the cards. If I were to grab 3 cards each with 3 tracks, I would guess the algorithm below would work on 4 of the 9 tracks in those cards. The algorithm I'm using looks like this (C#): private static char GetLRC(string s, int start, int end) { int result = 0; for (int i = start; i <= end; i++) { result ^= Convert.ToByte(s[i]); } return Convert.ToChar(result); } This is an example of track 3 data that fails the check. On this card, track 2 matched, but track 1 also failed. 0 1 2 3 4 5 6 7 8 9 A B C D E F 00 3 4 4 4 4 4 4 4 4 4 4 5 5 5 5 5 10 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 7 20 7 7 7 7 7 7 7 7 7 8 8 8 8 8 8 8 30 8 8 8 9 9 9 9 9 9 9 9 9 9 0 0 0 40 0 0 0 0 0 0 0 1 2 3 4 1 1 1 1 1 50 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 60 3 3 3 3 3 3 3 3 The sector delimiter is ';' and it ends with a '?'. The LRC byte from this track is 0x30. Unfortunately, the algorithm above computes an LRC of 0x00 per the following calculation (apologies for its length. I want to be thorough): 00 ^ 3b = 3b ';' 3b ^ 33 = 08 08 ^ 34 = 3c 3c ^ 34 = 08 08 ^ 34 = 3c 3c ^ 34 = 08 08 ^ 34 = 3c 3c ^ 34 = 08 08 ^ 34 = 3c 3c ^ 34 = 08 08 ^ 34 = 3c 3c ^ 34 = 08 08 ^ 35 = 3d 3d ^ 35 = 08 08 ^ 35 = 3d 3d ^ 35 = 08 08 ^ 35 = 3d 3d ^ 35 = 08 08 ^ 35 = 3d 3d ^ 35 = 08 08 ^ 35 = 3d 3d ^ 35 = 08 08 ^ 36 = 3e 3e ^ 36 = 08 08 ^ 36 = 3e 3e ^ 36 = 08 08 ^ 36 = 3e 3e ^ 36 = 08 08 ^ 36 = 3e 3e ^ 36 = 08 08 ^ 36 = 3e 3e ^ 36 = 08 08 ^ 37 = 3f 3f ^ 37 = 08 08 ^ 37 = 3f 3f ^ 37 = 08 08 ^ 37 = 3f 3f ^ 37 = 08 08 ^ 37 = 3f 3f ^ 37 = 08 08 ^ 37 = 3f 3f ^ 37 = 08 08 ^ 38 = 30 30 ^ 38 = 08 08 ^ 38 = 30 30 ^ 38 = 08 08 ^ 38 = 30 30 ^ 38 = 08 08 ^ 38 = 30 30 ^ 38 = 08 08 ^ 38 = 30 30 ^ 38 = 08 08 ^ 39 = 31 31 ^ 39 = 08 08 ^ 39 = 31 31 ^ 39 = 08 08 ^ 39 = 31 31 ^ 39 = 08 08 ^ 39 = 31 31 ^ 39 = 08 08 ^ 39 = 31 31 ^ 39 = 08 08 ^ 30 = 38 38 ^ 30 = 08 08 ^ 30 = 38 38 ^ 30 = 08 08 ^ 30 = 38 38 ^ 30 = 08 08 ^ 30 = 38 38 ^ 30 = 08 08 ^ 30 = 38 38 ^ 30 = 08 08 ^ 31 = 39 39 ^ 32 = 0b 0b ^ 33 = 38 38 ^ 34 = 0c 0c ^ 31 = 3d 3d ^ 31 = 0c 0c ^ 31 = 3d 3d ^ 31 = 0c 0c ^ 31 = 3d 3d ^ 31 = 0c 0c ^ 31 = 3d 3d ^ 31 = 0c 0c ^ 31 = 3d 3d ^ 31 = 0c 0c ^ 32 = 3e 3e ^ 32 = 0c 0c ^ 32 = 3e 3e ^ 32 = 0c 0c ^ 32 = 3e 3e ^ 32 = 0c 0c ^ 32 = 3e 3e ^ 32 = 0c 0c ^ 32 = 3e 3e ^ 32 = 0c 0c ^ 33 = 3f 3f ^ 33 = 0c 0c ^ 33 = 3f 3f ^ 33 = 0c 0c ^ 33 = 3f 3f ^ 33 = 0c 0c ^ 33 = 3f 3f ^ 33 = 0c 0c ^ 33 = 3f 3f ^ 3f = 00 '?' If anybody can point out how to fix my algorithm, I would appreciate it. Thanks, PaulH

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  • Organizations &amp; Architecture UNISA Studies &ndash; Chap 7

    - by MarkPearl
    Learning Outcomes Name different device categories Discuss the functions and structure of I/.O modules Describe the principles of Programmed I/O Describe the principles of Interrupt-driven I/O Describe the principles of DMA Discuss the evolution characteristic of I/O channels Describe different types of I/O interface Explain the principles of point-to-point and multipoint configurations Discuss the way in which a FireWire serial bus functions Discuss the principles of InfiniBand architecture External Devices An external device attaches to the computer by a link to an I/O module. The link is used to exchange control, status, and data between the I/O module and the external device. External devices can be classified into 3 categories… Human readable – e.g. video display Machine readable – e.g. magnetic disk Communications – e.g. wifi card I/O Modules An I/O module has two major functions… Interface to the processor and memory via the system bus or central switch Interface to one or more peripheral devices by tailored data links Module Functions The major functions or requirements for an I/O module fall into the following categories… Control and timing Processor communication Device communication Data buffering Error detection I/O function includes a control and timing requirement, to coordinate the flow of traffic between internal resources and external devices. Processor communication involves the following… Command decoding Data Status reporting Address recognition The I/O device must be able to perform device communication. This communication involves commands, status information, and data. An essential task of an I/O module is data buffering due to the relative slow speeds of most external devices. An I/O module is often responsible for error detection and for subsequently reporting errors to the processor. I/O Module Structure An I/O module functions to allow the processor to view a wide range of devices in a simple minded way. The I/O module may hide the details of timing, formats, and the electro mechanics of an external device so that the processor can function in terms of simple reads and write commands. An I/O channel/processor is an I/O module that takes on most of the detailed processing burden, presenting a high-level interface to the processor. There are 3 techniques are possible for I/O operations Programmed I/O Interrupt[t I/O DMA Access Programmed I/O When a processor is executing a program and encounters an instruction relating to I/O it executes that instruction by issuing a command to the appropriate I/O module. With programmed I/O, the I/O module will perform the requested action and then set the appropriate bits in the I/O status register. The I/O module takes no further actions to alert the processor. I/O Commands To execute an I/O related instruction, the processor issues an address, specifying the particular I/O module and external device, and an I/O command. There are four types of I/O commands that an I/O module may receive when it is addressed by a processor… Control – used to activate a peripheral and tell it what to do Test – Used to test various status conditions associated with an I/O module and its peripherals Read – Causes the I/O module to obtain an item of data from the peripheral and place it in an internal buffer Write – Causes the I/O module to take an item of data form the data bus and subsequently transmit that data item to the peripheral The main disadvantage of this technique is it is a time consuming process that keeps the processor busy needlessly I/O Instructions With programmed I/O there is a close correspondence between the I/O related instructions that the processor fetches from memory and the I/O commands that the processor issues to an I/O module to execute the instructions. Typically there will be many I/O devices connected through I/O modules to the system – each device is given a unique identifier or address – when the processor issues an I/O command, the command contains the address of the address of the desired device, thus each I/O module must interpret the address lines to determine if the command is for itself. When the processor, main memory and I/O share a common bus, two modes of addressing are possible… Memory mapped I/O Isolated I/O (for a detailed explanation read page 245 of book) The advantage of memory mapped I/O over isolated I/O is that it has a large repertoire of instructions that can be used, allowing more efficient programming. The disadvantage of memory mapped I/O over isolated I/O is that valuable memory address space is sued up. Interrupts driven I/O Interrupt driven I/O works as follows… The processor issues an I/O command to a module and then goes on to do some other useful work The I/O module will then interrupts the processor to request service when is is ready to exchange data with the processor The processor then executes the data transfer and then resumes its former processing Interrupt Processing The occurrence of an interrupt triggers a number of events, both in the processor hardware and in software. When an I/O device completes an I/O operations the following sequence of hardware events occurs… The device issues an interrupt signal to the processor The processor finishes execution of the current instruction before responding to the interrupt The processor tests for an interrupt – determines that there is one – and sends an acknowledgement signal to the device that issues the interrupt. The acknowledgement allows the device to remove its interrupt signal The processor now needs to prepare to transfer control to the interrupt routine. To begin, it needs to save information needed to resume the current program at the point of interrupt. The minimum information required is the status of the processor and the location of the next instruction to be executed. The processor now loads the program counter with the entry location of the interrupt-handling program that will respond to this interrupt. It also saves the values of the process registers because the Interrupt operation may modify these The interrupt handler processes the interrupt – this includes examination of status information relating to the I/O operation or other event that caused an interrupt When interrupt processing is complete, the saved register values are retrieved from the stack and restored to the registers Finally, the PSW and program counter values from the stack are restored. Design Issues Two design issues arise in implementing interrupt I/O Because there will be multiple I/O modules, how does the processor determine which device issued the interrupt? If multiple interrupts have occurred, how does the processor decide which one to process? Addressing device recognition, 4 general categories of techniques are in common use… Multiple interrupt lines Software poll Daisy chain Bus arbitration For a detailed explanation of these approaches read page 250 of the textbook. Interrupt driven I/O while more efficient than simple programmed I/O still requires the active intervention of the processor to transfer data between memory and an I/O module, and any data transfer must traverse a path through the processor. Thus is suffers from two inherent drawbacks… The I/O transfer rate is limited by the speed with which the processor can test and service a device The processor is tied up in managing an I/O transfer; a number of instructions must be executed for each I/O transfer Direct Memory Access When large volumes of data are to be moved, an efficient technique is direct memory access (DMA) DMA Function DMA involves an additional module on the system bus. The DMA module is capable of mimicking the processor and taking over control of the system from the processor. It needs to do this to transfer data to and from memory over the system bus. DMA must the bus only when the processor does not need it, or it must force the processor to suspend operation temporarily (most common – referred to as cycle stealing). When the processor wishes to read or write a block of data, it issues a command to the DMA module by sending to the DMA module the following information… Whether a read or write is requested using the read or write control line between the processor and the DMA module The address of the I/O device involved, communicated on the data lines The starting location in memory to read from or write to, communicated on the data lines and stored by the DMA module in its address register The number of words to be read or written, communicated via the data lines and stored in the data count register The processor then continues with other work, it delegates the I/O operation to the DMA module which transfers the entire block of data, one word at a time, directly to or from memory without going through the processor. When the transfer is complete, the DMA module sends an interrupt signal to the processor, this the processor is involved only at the beginning and end of the transfer. I/O Channels and Processors Characteristics of I/O Channels As one proceeds along the evolutionary path, more and more of the I/O function is performed without CPU involvement. The I/O channel represents an extension of the DMA concept. An I/O channel ahs the ability to execute I/O instructions, which gives it complete control over I/O operations. In a computer system with such devices, the CPU does not execute I/O instructions – such instructions are stored in main memory to be executed by a special purpose processor in the I/O channel itself. Two types of I/O channels are common A selector channel controls multiple high-speed devices. A multiplexor channel can handle I/O with multiple characters as fast as possible to multiple devices. The external interface: FireWire and InfiniBand Types of Interfaces One major characteristic of the interface is whether it is serial or parallel parallel interface – there are multiple lines connecting the I/O module and the peripheral, and multiple bits are transferred simultaneously serial interface – there is only one line used to transmit data, and bits must be transmitted one at a time With new generation serial interfaces, parallel interfaces are becoming less common. In either case, the I/O module must engage in a dialogue with the peripheral. In general terms the dialog may look as follows… The I/O module sends a control signal requesting permission to send data The peripheral acknowledges the request The I/O module transfers data The peripheral acknowledges receipt of data For a detailed explanation of FireWire and InfiniBand technology read page 264 – 270 of the textbook

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  • Problem Showing Sensors Details

    - by Skatephone
    Hi, i'm looking to show detail about sensors in an Actvity but when i put my app in to my phone i manage to view only details about the accellerometer, but the program says that i have 4 sensors: Accellerometer, Magnetic field, Orientation and Temperature. I'm using Android 1.6 and a htc Tattoo for testing. This is my code: public class SensorInfo extends Activity { private SensorManager mSensorManager; TextView mTextAcc,mTextGyr,mTextLig,mTextMag,mTextOri, mTextPre,mTextPro,mTextTem, mSensorsTotTitle,mSensorAvailablesTitle,mTextAccTitle,mTextGyrTitle,mTextLigTitle,mTextMagTitle,mTextOriTitle, mTextPreTitle,mTextProTitle,mTextTemTitle; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.detaillayout); // Get the texts fields of the layout and setup to invisible setTextViews(); // Get the SensorManager mSensorManager= (SensorManager) getSystemService(SENSOR_SERVICE); // List of Sensors Available List<Sensor> msensorList = mSensorManager.getSensorList(Sensor.TYPE_ALL); // Print Sensor Details Sensor sens; int type,i; String text = new String(""); // Do the list of available sensors on a String and print detail about each sensor for (i=0;i<msensorList.size();i++){ sens = msensorList.get(i); type = sens.getType(); text = " - "+getString(R.string.power)+" "+String.valueOf(sens.getPower())+"mA\n"; text+= " - "+getString(R.string.resolution)+" "+String.valueOf(sens.getResolution())+"\n"; text+= " - "+getString(R.string.maxrange)+" "+String.valueOf(sens.getMaximumRange ())+"\n"; text+= " - "+getString(R.string.vendor)+" "+sens.getVendor()+"\n"; text+= " - "+getString(R.string.version)+" "+String.valueOf(sens.getVersion()); switch(type) { // Check the type of Sensor that generate the event and show is resolution case Sensor.TYPE_ACCELEROMETER: mTextAccTitle.setVisibility(0); mTextAccTitle.setMaxHeight(30); mTextAcc.setVisibility(0); mTextAcc.setMaxHeight(100); mTextAcc.setText(text); // Print data of the Sensor break; case Sensor.TYPE_GYROSCOPE: mTextGyrTitle.setVisibility(0); mTextGyr.setVisibility(0); mTextGyr.setText(text); // Print data of the Sensor break; case Sensor.TYPE_LIGHT: mTextLigTitle.setVisibility(0); mTextLig.setVisibility(0); mTextLig.setText(text); // Print data of the Sensor break; case Sensor.TYPE_MAGNETIC_FIELD: mTextMagTitle.setVisibility(0); mTextMag.setVisibility(0); mTextMag.setText(text); // Print data of the Sensor break; case Sensor.TYPE_ORIENTATION: mTextOriTitle.setVisibility(0); mTextOri.setVisibility(0); mTextOri.setText(text); // Print data of the Sensor break; case Sensor.TYPE_PRESSURE: mTextPreTitle.setVisibility(0); mTextPre.setVisibility(0); mTextPre.setText(text); // Print data of the Sensor break; case Sensor.TYPE_PROXIMITY: mTextProTitle.setVisibility(0); mTextPro.setVisibility(0); mTextPro.setText(text); // Print data of the Sensor break; case Sensor.TYPE_TEMPERATURE: mTextTemTitle.setVisibility(0); mTextTem.setVisibility(0); mTextTem.setText(text); // Print data of the Sensor break; } } } // Get the texts fields of the layout and setup to invisible void setTextViews(){ mTextAccTitle = (TextView) findViewById(R.id.sensorAccTitle); mTextAccTitle.setVisibility(4); mTextAccTitle.setMaxHeight(0); mTextAcc = (TextView) findViewById(R.id.sensorAcc); mTextAcc.setMaxHeight(0); mTextAcc.setVisibility(4); mTextGyrTitle = (TextView) findViewById(R.id.sensorGyrTitle); mTextGyrTitle.setVisibility(4); mTextGyrTitle.setMaxHeight(0); mTextGyr = (TextView) findViewById(R.id.sensorGyr); mTextGyr.setVisibility(4); mTextGyrTitle.setMaxHeight(0); mTextLigTitle = (TextView) findViewById(R.id.sensorLigTitle); mTextLigTitle.setVisibility(4); mTextLigTitle.setMaxHeight(0); mTextLig = (TextView) findViewById(R.id.sensorLig); mTextLig.setVisibility(4); mTextLig.setMaxHeight(0); mTextMagTitle = (TextView) findViewById(R.id.sensorMagTitle); mTextMagTitle.setVisibility(4); mTextMagTitle.setMaxHeight(0); mTextMag = (TextView) findViewById(R.id.sensorMag); mTextMag.setVisibility(4); mTextMag.setMaxHeight(0); mTextOriTitle = (TextView) findViewById(R.id.sensorOriTitle); mTextOriTitle.setVisibility(4); mTextOriTitle.setMaxHeight(0); mTextOri = (TextView) findViewById(R.id.sensorOri); mTextOri.setVisibility(4); mTextOri.setMaxHeight(0); mTextPreTitle = (TextView) findViewById(R.id.sensorPreTitle); mTextPreTitle.setVisibility(4); mTextPreTitle.setMaxHeight(0); mTextPre = (TextView) findViewById(R.id.sensorPre); mTextPre.setVisibility(4); mTextPre.setMaxHeight(0); mTextProTitle = (TextView) findViewById(R.id.sensorProTitle); mTextProTitle.setVisibility(4); mTextProTitle.setMaxHeight(0); mTextPro = (TextView) findViewById(R.id.sensorPro); mTextPro.setVisibility(4); mTextPro.setMaxHeight(0); mTextTemTitle = (TextView) findViewById(R.id.sensorTemTitle); mTextTemTitle.setVisibility(4); mTextTemTitle.setMaxHeight(0); mTextTem = (TextView) findViewById(R.id.sensorTem); mTextTem.setVisibility(4); mTextTem.setMaxHeight(0); } } Tank's Valerio From Italy

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