difference between mp3 wav aac

 تعرف على الفرق بين مختلف أنواع الملفات الصوتية المعروفة ؟ MP3, AAC, WAV...

     لا شك أن الملفات الصوتية هي من الملفات التي نستعملها بشكل يومي, فأنت تتعامل معها عند استماعك سواء للقران, أو دروس أو الموسيقى, أو أي نوع من التسجيلات الصوتية. و لا يختلف اثنان على أن أشهر أنواع الملفات الصوتية هي ال MP3 لكنها ليست النوع الوحيد المتوفر على الأنترنت, بل هناك الكثير من الملفات الصوتية بصيغ أخرى, لذلك في هذه المقالة نتعرف على أبسط الفروق بين مختلف أنواع الملفات الصوتية, و عن أحسنها, و أيها يجدر بك استعمالها حتى تحصل على أحسن تجربة صوتية ممكنة ؟

ما الفرق بين Lossless Formats و Lossy Formats ؟

بالترجمة الحرفية :

 :  Lossless Format ملفات بدون خسائر.

 :     Lossy Format ملفات مع خسائر.

لكن المعنى الصحيح هو

Lossless Formats هي ملفات صوتية مضغوطة لكنها تحافظ في أغلب الأحيان على كل خصائص و جودة الصوت من المصدر الرئيسي بينما Lossy Formats هي ملفات مضغوطة بشكل جيد لتوفير المساحة مما يؤثر على جودة الملف الصوتي.

هناك نوع ثالث من الملفات و هي الملفات الغير مضغوطة بتاتا, نبدأ بشرحها هي الأولى

الملفات الصوتية الغير مضغوطة

هي نوعان : AIFF  و WAV .

و هما نسختان غير مضغوطتين تماما, أي أنهما نسخ متطابقة كليا مع الملف الصوتي الأصلي, الصيغتان معا توفران نفس الجودة, الفرق الوحيد بينهما هو اختلاف بسيط في كيفية تخزين البيانات.

صيغة WAV هي من أول الصيغ المطورة للحواسيب الشخصية (Pcs), طورت من طرف Microsoft و IBM مما يجعلها صيغة ذات صدا عالمي  عكس AIFF التي طورت من طرف APPLE حيت لن تجدها غالبا إلا في منتجاتها الخاصة.

الجدير بالذكر هو أن ملفات WAV و AIFF تأخذ مساحة كبيرة عكس صيغ الملفات الأخرى و متوسط مساحة التخزين هو 10 MB لكل دقيقة.

هل باستعمالي لهذين النوعين سأحصل على جودة صوتية أحسن ؟

في الحقيقة لن يكون هناك فرق واضح بين هذين الصيغتين و الصيغ الأخرى لأن الأمر يتعلق أيضا بجودة المعدات الصوتية التي تستعملها, الفرق الوحيد و الواضح هو أنك ستحتاج لمساحة أكبر من أجل تخزين عدد أقل من الملفات الصوتية لكن إن كنت تستعمل ملفاتك لأغراض الدمج فهذه هي الصيغ التي ستحتاجها لأنها تحافظ على كامل جودتها و خصائصها.

الملفات الصوتية المضغوطة

 Lossless Formats

و هي ثلاث أنواع

FLAC, ALAC و APE .

FLAC : The Free Lossless Audio Codec و هي أكثرها شهرة كما أنها مجانية و مفتوحة المصدر.

ALAC : Apple Lossless Audio Codec شبهة بصيغة FLAC غير أنها مطورة من طرف  APPLE, مما يجعلها مدعومة كليا من طرف ITunes و IOS عكس FLAC لكن عملية الضغط ليست بفعالية هذه الأخيرة أي أن ملفات ال ALAC هي في الغالب أكبر حجما من ملفات FLAC .

APE : Monkey’s Audio و هي ملفات جد مضغوطة, لذلك هي تأخذ مساحة أقل من FLAC و ALAC لكنها غير متوافقة مع جميع برامج تشغيل الملتميديا إضافة إلى أنها تتطلب عملا أكثر من المعالج لتفك تشفيرها نظرا لخوارزمية الضغط المعقدة التي تعتمد عليها.

عامة فإن الملفات من نوع Lossless يمكن تحويلها مرة أخرى إلى صيغة WAV دون فقدان أي من جودتها. كما أن متوسط مساحة التخزين لهذه الصيغة هو 5 MB لكل دقيقة لذلك أن كنت تتوفر على معدات صوتية ذات جودة عالية ينصح باستعمال أحد هذه الصيغ الثلاث حتى تحصل على جودة صوت عالية.

Lossy Formats

و هي الأكثر انتشارا بين الناس إذ أنها توفر مساحة كبيرة جدا حتى تستطيع إضافة ملفات صوتية أخرى حيت أن متوسط التخزين هو 1 MB لكل دقيقة. فرق كبير بينها وبين ما سبق شرحه في المقالة,  لكن كما سبق لي و قلت فإنها تفقد بعضا من جودة الملف الأصلي. غير ذلك يجب أن تعلم أنه كلما ارتفع معدل البت في هدا النوع من الملفات كلما تحسنت جودة الصوت فمثلا ملف بمعدل بث 192 Kbit/s سيوفر جودة أحسن من ملف بمعدل 150Kbit/s.

و هنا بعض أنواع هذه الملفات الأكثر انتشارا.

MP3 : MPEG Audio Layer 3 و هي الأكثر انتشارا في العالم نظرا للدعم الكامل الذي توفره جميع برامج تشغيل الملتميديا لها, رغم ذلك فإن صيغة MP3 تتوفر على كومة من العيوب التي بطبيعة الحال لم تستطع الحد من شعبيتها.

Vorbis صيغة مجانية و مفتوحة المصدر تستعمل فالغالب في معدات الألعاب.

AAC : Advanced Audio Coding هي صيغة توفر جودة مماثلة لل MP3 بمساحة أقل, صارت تستعمل غالبا مع الفيديوهات من نوع  MPEG4 و أيضا في ITunes.

WMA : Windows Media Audio مطورة من طرف ميكروسوفت توفر جودة مماثلة ل MP3 أو AAC لكن بدون أي مميزات أخرى.

أي هذه الصيغ يجدر بي استعمالها ؟

يبقى الجواب على هذا السؤال نسبيا لأن الأمر مرتبط بعوامل عديدة كالمصادر إذ أن أغلب الملفات الصوتية المتوفرة على الأنترنت هي بصيغة MP3 إضافة إلى المعدات الصوتية المتوفرة و كذلك المساحة التي تمتلكها من أجل تخزين ملفاتك الصوتية.


المصدر

Why is my Internet connection so slow?

No matter how fast your Internet connection is, there are times when things will slow down to a crawl. This article will help you sort out what kinds of things can go wrong, learn what you can do about them, and discover how to get the most from your Internet connection.

Windows provides a built-in troubleshooter that can automatically find and fix some common connection problems.

• Open the Internet Connections troubleshooter by clicking the Start button , and then clicking Control Panel. In the search box, type troubleshooter, and then click Troubleshooting. Under Network and Internet, click Connect to the Internet.

The type of connection you have makes a difference

The type of Internet connection you use is the most important factor in determining your connection speed. The three most common ways to connect to the Internet from home are dial-up, DSL, and cable. If you have a choice, cable is usually the fastest, but both DSL and cable are faster than dial-up.

Many Internet providers also offer Fiber Optic Service (FiOS), which connects to the Internet using light over an optical network. In your home, you still connect your computer through copper wiring. The advantage of FiOS is that it can provide higher speeds than traditional copper wire connections such as DSL or cable. Some Internet providers offer multiple options, depending on the area you are in. More populated areas are more likely to have FiOS available. Check with your phone company or Internet provider for more information.

If you use a dial-up connection, there are a couple of good ways to optimize your Internet speed. First, use the fastest modem you can. The fastest modem you can use will send and receive information at a rate of 56 kilobits per second (Kbps). You won't get a full 56 Kbps speed most of the time, but with a good phone line, you should approach at least 45-50 Kbps.

Second, make sure that your phone line is in good condition. If the telephone wiring in your home or business is old or deteriorating, you might be picking up stray signals or cross talk from other phone lines. These problems will slow your Internet connection because the modem will have to send the same information over and over until it's transmitted without interruption. Check your telephone wires to be sure they aren't damaged, frayed, or twisted around power or other telephone cables. If you notice crackling in your phones, you might want to contact your phone provider to have them check the lines inside and outside your home to make sure they are in good condition.

Tips for wireless network users

When connecting to a wireless network (Wi‑Fi), your Internet connection speed can be affected by both where your computer is located and whether other wireless devices are in the same area. Wireless networks operate on frequencies that are similar to those used by other devices, such as microwave ovens or cordless phones. Operating a 2.4 gigahertz (GHz) cordless phone next to your 2.4 GHz wireless laptop can cause interference, or completely block the wireless network connection. If you want to make phone calls while surfing the web, either use a wired telephone or a cordless phone that operates at a different frequency than your wireless network.

Proximity to the wireless access point or router, as well as physical obstructions, can affect the quality of your Internet connection. To improve your connection speed, move closer to the access point and make sure that there are no physical obstructions between the access point and your computer.

Computer woes: spyware, viruses, and other programs

The health of your computer can affect your Internet connection. Spyware and viruses can definitely cause problems, but your Internet connection speed can also be affected by add-on programs, the amount of memory the computer has, hard disk space and condition, and the programs that are running.

Two of the most frequent causes of poor Internet performance are spyware and viruses. Spyware can slow your system by interfering with your browser and monopolizing your Internet connection. Spyware monitors your Internet use and keystrokes, which adds delays. The problem is compounded when there are multiple spyware programs running at the same time. If the problem is severe enough, you can lose connectivity altogether. To get your Internet performance back, you should regularly run an antispyware program to clean out any spyware infestation. For more information, see Scan for spyware and other potentially unwanted software.

Computer viruses can also cause poor Internet performance. When a virus infects a computer, it installs computer code which will attempt to propagate itself, usually by sending copies of itself through e‑mail. Some viruses can multiply at the rate of hundreds of e‑mail messages per minute, which leaves little computing power and Internet connection bandwidth for anything else. Viruses often don't give any obvious indication that they are running, so it's best to run your antivirus software at all times. For more information about dealing with viruses, see Viruses: frequently asked questions.

Browser add-ons also cause performance problems. Browser add-ons are programs, such as multimedia add-ons, search bars, or other programs that usually appear on your browser's toolbar. Many browser add-ons can add to a rich browsing experience, offering multimedia or specialized document viewing. However, some add-ons can slow your Internet connection. If you suspect that add-ons are causing slow performance, try starting Internet Explorer in Add-ons disabled mode. Add-ons are disabled only for the session, but if you find your performance improves, you can use the Add-on Manager to turn them off permanently. To access the Add-on Manager from Internet Explorer, click the Tools button, and then click Manage Add-ons. For more information, see How do browser add-ons affect my computer?

Like all computer programs, Internet Explorer requires a certain amount of computing power, memory, and disk space to run efficiently. Every webpage you view is first downloaded to memory and then saved to temporary disk files. Running another program that is using lots of memory and computing power can compete with Internet Explorer and cause delays. If you find your Internet connection running slowly and you have other programs running, try closing them. If you want to run several programs, consider increasing the memory you have on your computer. Low disk space can also cause performance problems. You can increase your disk space by deleting Internet Explorer's temporary files. To learn how to delete temporary files, see Delete webpage history.

Occasionally, settings get changed in Internet Explorer that could possibly affect how Internet Explorer works. You can reset Internet Explorer to its default settings. For more information, see Reset Internet Explorer settings. Resetting Internet Explorer isn't reversible, so you should read the list of settings that are affected before resetting.

Outside factors that affect connection speeds

Unfortunately, there are events and conditions that are outside your control. Even with a fast connection, external factors, such as busy websites or spreading computer viruses, can slow the entire web. Popular websites can become overwhelmed with users. For example, when a television commercial mentions a website, many people might try to visit the site at the same time. If the website isn't prepared to handle the traffic, you might encounter delays.

During times of heavy computer virus outbreaks, the Internet can slow down. Many viruses spread by causing computers to send out hundreds or thousands of copies of the virus. This can slow the Internet by sheer volume. You can see what major outbreaks are currently happening by visiting your antivirus vendor's website, or the Security at Home website.

Local Internet congestion can also result in slower-than-normal connection speeds. These slowdowns occur when many people try to connect to the Internet at the same time, and they occur most often at peak activity times, such as after school hours when students get home and connect to the web.

If you're on a corporate network, general network and proxy server use can affect your Internet performance. Most network administrators monitor Internet use, and will try to keep people from doing things like downloading large files during peak hours. If you find that your Internet access is slow at times, you might discuss it with your network administrator.

note:

raffic=send +recive

despite of of send or recive could be affected individually and separately by those factors that i had mentioned before.source

GooGle secrets ثمانية اسرار في محرك البحث جوجل يمكن انك لم تسمع بها من قبل

GooGle secrets

لامجال للشك ان محرك البحث جوجل يعد من افضل محركات البحث واكثرها إستعمالا حول العالم ، مقارنة بمحركات البحث الاخرى المنافسة . لكن للاسف فليس الجميع يعرف كيف يستفيد باكبر نسبة معينة من محرك البحث جوجل ذلك لما يحتوي عليه هذا المحرك من اسرار وحيل يمكن انك قد سمعت بها ويمكن ستكون هذه اول مرة ستكتشفها من خلال هذه التدوينة .

1/معرفة الوقت والتاريخ في اي دولة .

بإستعمال الامرTime يمكنك معرفة الوقت والتاريخ في اية دولة دون الحاجة للبحث في مواقعاخرى ، كما يمكنك معرفة الوقت في مدينة بكتابة الامر Time + اسم المدينة التي تود معرفة الوقت بها .

2/ معرفة الجو

من المميزات الخفية التي يوفرها محرك البحث جوجل انه يمكنك معرفة الجو لأية دولة وكذلك لاية مدينة ،  فيكفي ان تكتب الامر weather مرفوقا بإسم الدولة او المدينة لكي يضهر لك تقرير عن حالة الطقس الحالية وكذلك حالة الطقس المرتقبة خلال 7 ايام المقبلة  بالوقت والتاريخ ، بالإضافة إلى سرعة الرياح ، الرطوبة وغيرها من المعلومات الجوية .

3/آلة حاسبة

يمكنك تحويل محرك البحث جوجل إلى آلة حاسبة تحل فيها اصعب العمليات الحسابة ، ذلك من خلال تطبيقه المتميز الذي يحل ابسط المعادلات الحسابية إلى اصعبها واكثرها تعقيدا يكفي ان تقوم بكتابة اي امر على سبيل المثال 5*10 او 2+8 وسقيوم محرك البحث بالحساب وإعطائك النتيجة صحيحة .

4/وحدة قياس

 كما هو الحال بالنسبة للحاسبة فإن محرك البحث جوجل يعطيك إمكانية تحويل وحدة قياس إلى عدة وحدات اخرى ، حيث يكفي ان تكتب العدد تم الوحدة بعد ذلك تضيف الكلمة To و كتابة اسم  الوحدة التي ترغب ان تحول إليها  كما في الصورة.

5/تحويل العملة

من المميزات التي استعملها بشكل يومي هي تلك الخاصة بتحويل العملة ، فمحرك البحث جوجل قادر على منحك سعر تقريبي لاي عملة تريد التحويل إليها من الدرهم المغربي إلى اليورو او من الريال السعودي إلى الجنيه المصري ... وغيرها . فيكفي ان تقوم بكتابة المبلغ + العملة ثم تكتب الكلمة اللاثينية To وبعد ذلك تكتب رمز العملة الذي ترغب ان تحول اليها المبلغ على سبيل المثال :  1euro  to moroccan dirham


6/تتبع الحوالات

من الامور الجميلة جدا هي ان محرك البحث يستطيع إعطائك مكان تواجد مشترياتك من خلال الانترنت عن طريق Tracking Code فكما تعلم عند إختيار توصيل مشترياتك عن طريق الانترنت بإستعمال خدمة توصيل مدفوعة ك UPS, FEDEX فإن هذه الاخيرة تمنحك كود يسمى بــ Tracking code  الاخير الذي يساعدك في معرفة اين وصلت سلعتك ، ويمكنك تتبع رحلتها إلى حين ان تصل إلى بلدك . هكذا فإن محرك البحث جوجل يساعدك في ذلك فقط عبر إدخال Tracking code  إلى محرك البحث حيث يمكنه ان يعطيك مكان تواجد السلعة كما هو موضح في الصورة . 


7/ تتبع رحلة جوية

غريب اليس كذلك ؟ نعم محرك من اسرار البحث في جوجل انه قادر على إعطائك وقت إنطلاقة ووصول الطائرة من وإلى وجهتها فيكفي ان تكتب اسم الخطوط الجوية تم رقم الرحلة لكي يضهر لك وقت وتاريخ الوصول . كما في الصورة كلمة united هو إسم شركة الطيران الرقم 8 هو رقم الرحلة.


8/ معجم

نعم محرك البحث قادر ان يلعب دور المعجم وإعطائك تفاسير للكلمات اللاثينية التي تبحث عنها حيث يكفي ان تكتب define ثم إسم الكلمة التي تبحث عن تعريفها بالإضافة إلى إعطائك طريقة نطقها الصحيح .


المصدر: المحترف

Hacking Windows Password - SAM file [Securing & Cracking]

(Security Accounts Manager)  >> SAM



SAM file cracking with Ophcrack 

" Hi folks. It happens with many peoples including that you forgot the windows account password and having troubles in Login process OR you simply want to know the Password of your schools or Friends PC ".

Well then I think again its time to crack the Hashes in an easy way. Yeah I know that there are ways to reset the password like RESET WINDOWS PASSWORD but here I'm talking about viewing the password. There is a cool bootable CD called Ophcrack which allows you to crack the hashes using rainbow table and is available in simple GUI.

Its a small linux distribution with a tons of features but very popular for its easy and fast hash cracking feature. I'll cover the detailed features of ophcrack in future article soon.

Basic: Windows uses NTLM hashes to encrypt the password file which gets stored in SAM file. We simply need to target this file to retrieve the password

Tools Required:

• Ophcrack Live CD. Download from here
• Time and Patience

Lets get started....

Insert the Ophcrack Live CD and Boot your PC. Make sure the Boot from CD is the first option in the Boot menu at BIOS.
You'll get the Startup menu.

here choose Ophcrack Graphic mode - automatic
After few old loading shots, it'll redirect to the Linux Desktop. There Click on menu > Run

In the pop up box type > ophcrack click ok

Now you can see the ophcrack application windows. Here, click on Load > Encrypted SAM

After that we need to give the path to SAM directory which is by default /mnt/hda1/WINDOWS/System32 click choose

Here we can see the saved hashed now with the username and userid.

Now click on Crack button and wait for the password. Its quick and easy

That's it. It'll show the password now Have fun with the cracked password.

Note: Ophcrack is a live Linux CD, it may not work on all the versions of Windows 7 however its working fine with Windows XP/Vista.

SAM file cracking Offline NT Password & Registry Editor 

You can do this with a small tool called  Offline NT Password & Registry Editor. This utility works offline, that means you need to shut down your computer and boot off your using a floppy disk, CD or USB device (such as pen drive). The tool has the following features:

• You do not need to know the old password to set a new one.


• This tool can detect and unlock locked or disabled out user accounts!


• There is also a registry editor and other registry utilities that works under linux/unix, and can be used for other things than password editing.

How it Works?

Most Windows operating systems stores the login passwords and other encrypted passwords in a file called sam (Security Accounts Manager). This file can be usually found in \windows\system32\config. This file is a part of Windows registry and remains inaccessible as long as the OS is active. Hence, it is necessary that you boot off your computer and access this sam file via the boot menu. This tool intelligently gains access to this file and will reset/remove the password associated with administrator or any other account.

The download link for both CD and floppy drives along with the complete instructions is given below:

Offline NT Password & Reg Editor Download

It is recommended that you download the CD version of the tool since the floppy drive is outdated or doesn’t exist in today’s computer. After the download, you’ll get a bootable image which you need to burn it onto a blank CD. Now, boot your computer from this CD and follow the screen instructions to reset the password.

Another Simple Way to Reset Non-Administrator Account Passwords:

Here is another simple way through which you can reset the password of any non-administrator accounts. The only requirement for this is that you need to have administrator privileges. Here is a step-by-step instruction to accomplish this task:

1. Open the command prompt (Start -> Run -> type cmd -> Enter)
2. Now type net user and hit Enter
3. Now the system will show you a list of user accounts on the computer. Say for example, you need to reset the password of the account by name John, then do as follows:
4. Type net user John * and hit Enter. Now, the system will ask you to enter the new password for the account. That’s it. Now you’ve successfully reset the password for John without knowing his old password.

So, in this way you can reset the password of any Windows account at times when you forget it so that you need not re-install your OS for any reason. I hope this helps.

Securing SAM file with SYSKEY

Syskey protects the NT system by further encrypting the NT password database and can be used to prevent book without the knowledge of a special system password.

The Security Accounts Manager (SAM) stores the user passwords in a protected database. The original Windows NT 4.0 database is protected by several techniques:

• Permissions on relevant Registry keys are set to allow only the operating system access.
• Permissions on the Registry folders and files are limited. When the system is in operation, the SAM cannot be copied, or accessed directly except by the system and administrators.
• The passwords are obscured by a one-way function (OWF). This OWF is not decryptable. However, anyone obtaining a copy of the database can use dictionary and brute-force attacks in an attempt to crack or guess the passwords. In a dictionary attack, the same OWF is applied to each word in a dictionary listing, and then the result is compared to the obscured password. A match means the password equals the dictionary word. A brute-force attack compares the password OWF to an OWF of every possible combination of available characters.

Windows NT password-cracking programs have been available for several years. (You can download an evaluation version of the famous LophtCrack tool from http://www.@stake.com.) Although to use them directly against the SAM requires Administrator privileges, a backup of the SAM can be used offline by an attacker. (This is an excellent reason to practice good physical security!) Microsoft developed Syskey to protect the SAM from these types of attacks. Files that support Syskey as well as the program SYSKEY.EXE were incorporated in Service Pack 3 and all later service packs. Syskey uses a 128-bit key to encrypt the password portion of the user database in the SAM. When it was introduced, existing cracking programs could no longer be used to attack the password database.
Unfortunately, additional programs that can be used to provide a crackable database to LophtCrack are now available. These tools, pwdump2 and pwdump3, must be run by a member of the Administrators group in order to be successful. LophtCrack 3.0 does not need these tools; LophtCrack 3.0 can be used directly against a Syskey-protected SAM.
Nevertheless, you should use Syskey to protect the SAM for four reasons:

• If you use appropriate security practices and limit administrative accounts and require the use of strong passwords, you will mitigate the threat of pwdump2 and Lophtcrack 3.0 being used interactively on your systems. Indeed, if an administrative account has been compromised, there may be little need for cracking passwords in the SAM at all because the administrative account can be used to access any resources protected by DACLs.
• You have no way of knowing what the attacker is able to deal with, nor what weapons he has in his arsenal. Just because there are armor-piercing bullets should not prevent me from wearing armor if I may be shot at. The bullets fired at me may be of the regular kind, and I will survive the attack.
• It is always a good idea to layer security on your system. Each problem that you throw in an attacker's way decreases your risk of compromise. If you make attacking your network difficult, many attackers will move on to "lower hanging fruit."
• For a nonadministrative user to use these tools against your SAM, he must somehow obtain a copy of the SAM and use the tools offline. Good security practices can reduce the possibilities of an attacker obtaining a copy of the SAM. Servers, especially domain controllers, should be physically secured. Emergency Repair Disks and backups of the Registry need to be physically secured. The C:\WINNT\Repair directory (which holds a copy of the Registry when the RDISK program is run to create an ERD) needs to be protected, and Registry files can be removed from this location.

Implementation

The key used to encrypt the passwords is randomly generated by the Syskey utility. This Password Encryption Key (PEK) is itself encrypted with a randomly generated "System" key (Syskey) and stored in the Registry. Encrypting the PEK prevents compromise of the encrypted passwords. If the PEK were stored unencrypted in the Registry, it might be obtained and used to decrypt the passwords. The Syskey must be present for the system to boot. However, now there is a problem: how to protect the Syskey. This protection may be implemented in one of three ways:

• The Syskey is obfuscated and stored in the Registry. System can boot without administrative action.
• The Syskey is obfuscated and placed on a floppy disk that must be present when the system reboots. The Syskey is not stored anywhere on the system. The key is stored in a file call STARTKEY.KEY. Do not store the key on an ERD. To do so would be to provide two items needed to attack your system in one location. Do make copies of the disk. Without it you cannot boot your Windows NT system.
• A passphrase is entered and then used to create encrypt the Syskey. An MD5 cryptographic hash (digest) of the Syskey is stored in the Registry. The password must be entered during system boot to make the system usable.

In either the floppy disk choice or the password choice, the Syskey is not stored anywhere on the system. Therefore, these choices are more secure. If the floppy disk is lost or becomes corrupt, however, or if the password is forgotten, the system cannot be booted.
To apply the additional security provided by using Syskey, follow the procedure listed in Step by Step 1.

STEP BY STEP 1 Applying Syskey Protection to the SAM

1. Create a backup copy of the Registry prior to completing the additional steps. Be sure to label the backup as pre-Syskey, and store it forever. The only way to recover a Syskey-protected SAM if the Syskey is lost or corrupted is to restore from this pre-Syskey backup of the SAM.
2. Check the service pack level. Apply the most current service pack. (Service Pack 3 was the first service pack to incorporate Syskey.) Applying the most current service pack adds the code necessary to use Syskey.
3. If you applied a service pack in step 2, you might want to make another backup of the Registry. Label this one as post-SP and pre-Syskey.
4. From a command prompt, enter the Syskey.exe command.
5. In the pop-up window, check the radio button to enable strong encryption.
6. Select the choice of Syskey operations by selecting the radio button that matches your choice on the windows as shown
   
   
   .
   
7. If you have selected to enter a passphrase, do so now.
8. If prompted, provide a floppy disk.
9. Click OK.
10. A pop-up window will indicate success.
11. Reboot the system.
12. Make a new backup of the Registry and label it post-Syskey.
13. Repeat the process for each domain controller (the Syskey is not replicated) or Windows NT 4.0 workstation that is to be protected.
    
     Selecting the Syskey storage method.
    
    
    

The Syskey program may be used to change the Syskey option, or to generate a new Syskey at a later time. It may not be used to bypass Syskey security. If the key is stored on a floppy disk, the disk must be present. If the key is passphrase-derived, the administrator much know the passphrase before being able to rerun Syskey.

Wondering if their is a way to get the local passwords even with encrypted SAM file !!!yes..
but for more visit this links 1 , 2

Sources -::- 1 , 2

القنبلة الفراغية - Thermobaric Bomb - АВБПМ

القنبلة الفراغيـــة:

☼◄هي الأقوى من نوعها في العالم . تصنّع كل من القوتان العضمتان هذا النوع من القنابل وتطلق عليه الولايات المتحدة اسم "أم كل القنابل" بينما تطلق علية روسيا − كناية بالولايات المتحدة − اسم "أبو كل القنابل".

تقرير عرض على القناة الأولى الروسيه في عام 2007 يتحدث عن القنبله الفراغيه الروسيه التي تم تطويرها حديثاً.

لتشغيل الترجمه إضغط على زر CC

ما الداعي إلى استخدام هذا النوع من القنابل؟

☼◄ في مقالة نشرتها (منظمة الأمن الكوني العسكرية) على موقعها في الإنترنت أشارت إلى أن الأهداف تحت الأرضية كالمخابئ والمخازن والأنفاق التي لا تصل إليها الأعتدة التقليدية غير القادرة على اختراق مثل هذه التحصينات، يمكن استهدافها بالقنبلة الفراغية ولا سيما في مداخل الأنفاق أو مخارجها فتؤدي الي انفجارات ثانوية داخل النفق بسبب عاملَيْ التفريغ والتعويض السريعين في ضغط الهواء، مما يؤدي إلى تدمير البنية الهيكلية للنفق وما يحتوية من مخازن أو غرف قيادة، مهما كان شكل النفق أو عدد طبقاته، وما يمكن أن يحتويه الأجهزة والمعدات والأحياء، كما أن توقف الأداء التكتيكي لبنية النفق أو التكوين تحت الأرض بعد التفجير الفراغي يطلق عليه بلغة العسكر (القتل الوظيفي)Functional Kill ويكون القتل الوظيفي دائمياً تماماً كالقتل الهيكلي Structural Kill الذي يتحقق بالتفجيرات التقليدية، اعتماداً على دور المنشأة الحربي ومستوى التدمير الحاصل فيها.

تأثير القنبلة الفراغية على البشر:-

يؤدي انفجار القنبلة الفراغية إلى توليد حرارة عالية وضغط إيجابي سريع من استهلاك الأوكسجين داخل المنطقة المحصورة كالكهف أو النفق. وإذا نجا الأحياء داخل هذه المواقع من انهيار النفق ومحتوياته فإنهم سيلاقون الهلاك بسبب فرق الضغطين المتولدين، أو مخنوقين بسبب استهلاك الأوكسجين، وربما بسبب هذه العوامل مجتمعة.

Thermobaric Bomb

Probably the most powerful conventional (non-nuclear) weapon in the world today is Russian “Aviation Thermobaric Bomb of Increased Power” (ATBIP, Russian: Авиационная вакуумная бомба повышенной мощности (АВБПМ)), nicknamed "Father of All Bombs" (FOAB) (Отец всех бомб). It is a Russian-made air-delivered / land activated thermobaric vacuum bomb with the same destructive power as a small tactical nuclear weapon. 

VIDEO

FOAB overview

Blast yield of 44 tons of TNT produces just 7.8 tons of a new type of high explosive (explosive that produces supersonic velocity “shock front” and higher temperatures), developed with the use of nanotechnology. The bomb contains a 6,400 kilogram (6.4t) charge of a liquid fuel such as ethylene oxide, mixed with an energetic nanoparticle such as aluminium, surrounding a high explosive burster.

he bomb was successfully field-tested in the late evening of September 11, 2007. In describing the bomb's destructive power, Russian deputy armed forces chief of staff Alexander Rukshin was quoted as saying, "all that is alive merely evaporates". According to the Russian military, the new weapon will replace several smaller types of nuclear bombs in its arsenal.

Comparing to U.S. military's GBU-43/B Massive Ordnance Air Blast bomb (official military acronym "MOAB" is often colloquially said as the "Mother of All Bombs"), the FOAB is 4 times more poberful (44t compared to 11t of TNT) beside it’s smaller size and weight (7.1t compared to 8.2t). FOAB also have larger blast radius (300m compared to 150m) and twice higher temperature at the centre of the blast is due to nanotechnology.

How vacuum bomb works?

Vacuum bomb (high impulse thermobaric weapon or fuel–air explosive) differ from conventional explosive weapons by using oxygen from the outer air. As result, they produce more energy than normal weapons but are harder to control. Their reliance on atmospheric oxygen makes them unsuitable for use underwater or in adverse weather, but they have significant advantages when deployed inside confined environments such as tunnels, caves, and bunkers.

This bomb produces two blasts, the first being the dispersion of a cloud of liquid or powder explosive using a small detonating charge, and then the main explosion, when a second charge ignites the cloud, producing the actual deflagration.

A typical thermobaric weapon contains a mix of a monopropellant fuel explosive and a highly energetic material, like powdered aluminum, and usually consists of a container packed with a fuel substance, in the center of which is a small conventional-explosive "scatter charge". Fuels are chosen on the basis of the exothermicity of their oxidation, ranging from powdered metals such as aluminium or magnesium, or organic materials, possibly with a self-contained partial oxidant. The most recent development involves the use of nanofuels.

For more details check these links:   Father of All Bombs wikipedia   Vacuum bombs wikipedia