Category Archives: Computer Science

How to Make a Good and Strong Passwords

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Today we often use passwords for various applications such as email, blogs, social websites (facebook, twitter), or perhaps also to our cell phones. So how good or strong password that you use? The easiest way to find out is to calculate the likelihood we can guess passwords or in other words the possibility of which can be produced from a long string of characters or letters that you use in your password. More and more combinations that may be generated, it will be increasingly difficult to guess your password or hacked.

A simple example like this. If you use a cell phone using a password that is a 4 digit number, then chances are your phone password can be guessed is about 1 in 10,000 (figures 0000 up to 9999). If you use 8 characters for your email password, then it is likely to guess your password is 26 x 26 x 26 x 26 x 26 x 26 26 x 26 = 208 827 064 576 or more than 208.8 billion possibilities! but if you use your name … like “putriayu” or “ekoparto” it can increase the likelihood of predictable only in a matter of dozens of possibilities!

Therefore, if you want to create a good password you should not use the name (either your name, parents, relatives, siblings, people close to you), date (either date of birth, celebration, or special days), the words that you usually fave or enjoy, a commonly used word, or word that is predictable people (because they know the inherent vice of your choice).

There are a few tips for creating passwords:

* Use digit combination of numbers and letters
* Use characters like “@#$_%%^&*(” or the other if possible.
For example, use words that you will remember but hard to guess people, for example: “7an & / gi”.
* If possible, use a variety of characters or more letters. For example, if the letter “A” and “a” are considered different, then use these variations. For example: “7AN & / gi”. The possibility to guess it: more than 44.23 trillion!

The essence of making a good password is actually your confidentiality. How far / strong you are holding your password to not be notified to the other person, or convenience of others to guess your password. Therefore, if you’ve finished using an application, be it email, facebook, or anything else, immediately do the “sign-out” or “logout”.
Also, if possible change the passwords on a regular basis, say once a month or when a high risk to change the password once a week.

But if you are a forgetful, then to try to make it easier to make a password passwords pattern known only to you. for example, use and remember simple words like “maju2x”, “2 + TWO = four ‘, and so forth. But remember, that words are only you and God alone knows

Three Easy Steps to Remember the Hard Password

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When you want to create a password or pin code atm, of course you want the password that you create are difficult for others to guess but easy to remember. Actually there are many ways you can use to create passwords are hard-easy.

Use a combination of character as much as possible

An easy way to create a password that is difficult is to use a combination of character as much as possible. This method is essentially to maximize the use of characters, letters, numbers, punctuation, and other special characters. More and more combinations of letters, numbers, or special characters you use will make the password will be increasingly difficult for the uprooted. for example, people will more easily guess the word ‘mypassword’ rather than ‘iP455w012D’. whereas the same number of characters used: 10 pieces of character.

Creativity

In addition to using combinations of characters more, to make a difficult but easy to remember passwords is creativity. So how do I remember it so easy? at the time of initial manufacture of the password, you should be able to select a password that is associated with something, good people, events, joy, hatred, secrets, or other. But remember, as much as possible do not use family data or the people closest to you, such as date of birth of parents, marriage, etc.. If you want to use it, combine it with other things. in general, if someone knows about the family or the people closest to you, then he will be easier to guess your password. If you want to insist on using dates, change them to not like the usual format (month-day-year), try changing the format year-month-day, or day-month-year. so even using date, that date will not be easy to get caught. or it may be like using your email address: “support89@mail89.com”, mathematics: “8 / 3 # seven”, chat: @ smile ;-) , and much more.

Classification

Once you find a password that is good and easy to remember, keep your passwords and keep them from anyone, including your girlfriend or your family. Use this new password to any common things that require passwords “basic level”. That “basic level” are the things that are not too important, but should be kept secret. eg correspondence document. But if there are more important, then you must use the password “medium level”. And for a very important thing, then you must use the password “top level”. For all three types of password, make sure it was just a secret between you and your God, and if there is an indication of your password is revealed, quickly change the password, or if you want more secure, change your password periodically.

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How to Take Care of Your Computer with Easy and Simple

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Although computer prices fell rapidly, but remember that when we bought it the price is still expensive. therefore we must maintain and care for which we have bought a computer so that these conditions remain prime and we can use it well. To take care of this computer I have 8 tips or how to treat the computer with ease:

1. Keep your computer clean.
Clean the outside (monitor, keyboard, mouse, etc.) and the inside of the computer (motherboard, power supply, etc.) on a regular basis. To the outside using a soft cloth and a special liquid (if you know and believe will be beneficial). While for the inside use a brush or paintbrush. If you’re unsure or feel do not have the knowledge, then try asking your guidance person or friend who is more expert.
If you would like to eat, drink and smoke near or in front of a computer, then these habits you should avoid because of the possibility of food crumbs, coffee or nicotine from cigarettes will be signed and attached to the computer components that may be causing damage.

2. Guard Voltage Power
When the voltage in your house is less stable, then you should use a guard or a voltage stabilizer (stavolt). For more reliable, use a tool that uses batteries to keep if at any time when the electricity goes out. Also, do not turn off the computer by directly cutting off the flow of electricity a computer, either via the power button, switch, unplugged, or the other.
To keep the process turn the computer does not take drastic electrical voltage, turn on the monitor, CPU, and other devices one by one (not simultaneously).

3. Keep the Computer Temperature
If you use a computer long enough, make sure the processor temperature is always in a particularly cold or stable condition and is still within the limits of tolerance. If necessary add a cooling fan / blower or other cooling devices to keep the processor temperature is always kept cool. If urgent, do the installation of software / programs to protect and cool the processor, while for the monitor you can set the screen saver and power settings.

4. Keep away from magnetic objects
Keep your computer from magnetized objects, or vice versa, keep magnetic objects away from your computer. Magnetized objects not only interfere with the monitor, but can also interfere with components in the computer CPU.

5. remove unused device

Eject CD / DVD from the CD / DVD drive when it is not used anymore. thus the computer does not always check the contents of the CD / DVD. so that the lifetime of the disk and CD / DVD drives will be longer. Do the same for flash drives.

6. Avoid computer silenced for too long.
Computers are not used for too long will be dewy. If you want to shut the computer for a long time, use the silica gel or other materials that can absorb water moisture in the air.

7. Use with care.
If you often play games of course belongs to your keyboard and mouse will be more quickly broken. Therefore, avoiding the keystrokes or mouse clicks that are too strong. In addition, you must frequently adjust the settings to cycle through the use of keyboard keys before the key is damaged

8. Keep away from small creatures
If your house is not clean from the small creatures such as cockroaches or lizards, then you should be more careful so that these creatures do not enter into the hole in your PC. Another solution, replace your PC with a laptop or notebook computer. :D

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How to Highlighting Texts and Pictures in Microsoft Word Using Your Mouse and Keyboard

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Highlighting with SHIFT
When editing a document using Microsoft Word we sometimes or even often make a block of text or highlighting it using the mouse. So, did you ever try to make a block of text by combining key presses like ALT, SHIFT or CONTROL?
Click on or place the cursor at the beginning of a text editor that will be on the block, then go to the end of the block and press SHIFT + click the left mouse button. This will simplify the way to make a block when the block area consists of multiple pages, so we do not need to drag it from the beginning of the block until the end of the block.

Press the CTRL key when we want to make a block that consists of several areas of the block. This step is generally used to select the picture (you can also use the SHIFT key), while for the text you can do this by dragging the mouse.
See in the image below. There are three words “keyboard”, “ins”, and “press” which is being highlighted. If you do copy and paste then the those three words will be arranged sequentially down.

Highlighting with CONTROL

Press the ALT key if you want to create a block that resembles a box. This method is very useful for doing the editing lines had similar contents, generally in the form list….
Highlighting with ALT
In the next example you can see the highlighting is limited only to the phrase “similar line” that existed at the third row up to the ninth.

So, would you like to try practicing highlighting text and images by using the ALT, SHIFT and CONTROL? Run your Microsoft Word and try it now .. ;)

Tips when Working with Tables in Microsoft Word

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In our document sometimes we use tables to display data or the results of the analysis that we have made. The tables can present the data or information in a more concise and accurate. From my experience using Microsoft Word, it was hard-easy to work with it tables.

1. Inserting Multiple Lines Simultaneously
If you want to quickly add a few rows in a table, then first you should create a block of a few rows that you want. It means if you want to insert 4 rows then you should create a highlight or block of 4 rows, and so on. Then right click your mouse button to display the popup menu, then select the insert rows item. Then the tables will be inserted row with the number of rows that you previously block.
After that, you also can inserting the same number of rows by repeating the last command by pressing [F4] or [CTRL] + [Y] (see also: tips for typing faster with the keyboard shortcut). For example, if you previously had to insert four rows, then you can get 40 rows by pressing the [F4] or [Ctrl] + [Y] as much as nine times more.

2. Deleting Several Rows at Once.
Like the insert row, block a few lines to be removed first. Then right click your mouse button to display the popup menu, and then select the menu item delete rows. It will delete those rows.

3. Adding Rows at the End Table.
To quickly add one or a few rows at the end of a table you may using this method: click or put the editing cursor on the bottom line. Press the [Tab] button and hold it. Editing cursor will move in the right direction and if it has arrived at the end of the table, the cursor will automatically move downward and will add a new row. Release the [Tab] button when the number of added rows is accordance with what you need.

4. Avoid Tables that are too long and Complex
if you have created a document that contains a table which is the result of a merger or the format of many cells, then that’s not good for your document. Because it will takes more time to edit or save the document. To solve this problem, first you can break the table into several smaller tables (e.g. based on serial numbers, groups or categories) with the same format.
The second alternative, you can divide the document (into several files) that much smaller.

5. Consider using a spreadsheet
If you really have a long table then you should consider the combination of spreadsheet (like Microsoft Excel) for your tables and Words processor (like Microsoft Word) for narration.

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Accelerating Paste Value in Microsoft Excel

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When using Microsoft Excel, sometimes or maybe often we use to fill a number in a cell by using the paste values function. It is most often done for doing this is (1) right click on the cell that will be filled, (2) choose paste special menu item, (3) click on the option value, (4) click OK . Actually we can save these four steps into one step only: a click on the paste values button in the toolbar. By default the button is missing on the toolbar, so you have created yourself.

a. For microsoft Office 2003 or older:
Tombol toolbar Paste Values

  1. right-click on any toolbar area;
  2. on the popup menu choose customize menu items;
  3. on a popup window, select commands page;
  4. select edit category, then find paste values command;
  5. add to the toolbar button by dragging the paste values button into the toolbar;
  6. close the popup window.

b. For Microsoft Office 2007
Tombol toolbar Paste Values

  1. Right click on the Quick access toolbar area;
  2. Choose Customize Quick access toolbar on the pop up menu;
  3. Then on popup window, select the all commands item from commands dropdown list;
  4. locate and select Paste Values items;
  5. click the Add button;
  6. close the pop up window.

Your paste values button is ready for use. You can click on the button whenever you need the paste values function.

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How to Assemble a Computer with a Cheap Price

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There are many good personal computers with cheap price. And one of these computers could be a computer that assembled by yourself. In many case, we can get better quality and specification with same price. So how do we assemble a computer with a cheap price but get a quality computer that is satisfactory?
Like going to buy a new or secondhand computer (or computer upgrading as well), we must take into account our needs well and then determine the specifications of components or parts that we will buy or upgrade a computer.

1. Computer Specifications

If you want a cheap, of course, specify the minimum computer specifications. But if you want cheap computers with good ability, determine the optimal specifications of the computer. The optimum computer specifications mean you can work better with computers rates slightly above the minimum performance that you need. Generally, your computer’s performance can be improved by increasing the computer memory (RAM) capacity or using a faster hard drive. Moreover, you can save your money by not using the Intel Pentium (Core Duo, etc.), instead you can use a Celeron or AMD processor.

2. Onboard Components

Select a motherboard that supports VGA, soundcard, network interface card, and other cards are available onboard. Thus the total cost will be cheaper.

3. Shared Memory

if you are a graphics designer or game player, so you need more VGA support. In this case, you should choose the motherboard and the vga that support for using computer RAM.

4. Secondhand computer components

you can reduce computer price by using secondhand computer spare parts. There are so many components that still have a good quality. Screen or monitor is a big thing that you can deal with it because old and new monitors have a fairly significant price difference.
However, be careful in selecting, choose the parts or components that are still good and provide warranty service.

5. Buying it from one computer store

Sometimes for a cheap price of computer components we must get it from one store for a component and from other store for the other components. But the price from a computer store that within a row of computer store generally would be same between one store and another. So, pick one store that you think it has a cheaper price and then buy everything that you may need from that store and try to get discount from it.

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How To Speed Up Your Computer Performance Easily

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Generally computer performance was influenced by processor, RAM, VGA and hard disk. I have several ways to keep and speed up my computer performance :

 

  1. Check your computer for any spyware, virus, adware or any other parasite program.

     
  2. Install one anti-virus only on your computer. If available, update the anti-virus daily. Using more than one anti-virus will lead to memory (RAM) consumption and conflict between it.

     
  3. Don’t run too many programs simultaneously. It will consume more memories (RAM) and spend time for swapping data from virtual memory on your hard disk to RAM, and from RAM to virtual memory. Close any unnecessary application and let you work with main application only.

     
  4. Reduce or limit the number of start-up program. (See above). If exist any start up program that can run manually, remove it from start up and you may load it only when you really need it.

     
  5. Uninstall every unnecessary program. If you do that, you will reduce memory consumption by unnecessary program and at least you will gain more space on your hard disk.

     
  6. Delete old temporary files. It will become helpful if you run out of space.

     
  7. Update computer program and driver regularly. So that program or driver did not run under compatible mode.

     
  8. Don’t place too many shortcuts or files on your desktop. The Operating system will need more extra time when it need to refresh the desktop.

     
  9. Use Disk Defragmenter regularly. File fragmentation will make file loading process slower. You can fix it with Disk Defragmenter tool.

     
  10. Set the initial size of virtual memory at least to the number that recommended by the operating system. So when it need to grow, it will not make too many fragmentation.

     
  11. If available, Place the virtual memory and the system temporary folder in one special drive. So it will not intrude the file fragmentation on another drive.

     
  12. Use separate drive for both the operation system files and the data files. It will reduce the file fragmentation probability.

     
  13. Immediately eject any CDs/DVDs and also unplug any USB or other media after you use it. It will reduce the frequent of media detection by the operating system or also by anti-virus scanning.

     
  14. Do not doing install-uninstall programs too often. It may harm your computer operating system, the registry at least. Use registry cleaner program to fix it. The other way, you can save system configuration before you installing any test software and restore it immediately after you done.

     
  15. Disable all animations, wallpaper, sound effects, or any multimedia aspects that you do not work with it.

     

If all tips above doesn’t work with your computer, I have one last tip that the most powerful and easiest way to speed up your computer: sell it and buy a new one. :D

 

    

Genetic Local Search(GLS) : Traveling Salesman Problem (TSP) Solver

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A Traveling Salesman Problem (TSP) is one of optimization problem. TSP as a problem which “easy” to understand but hard to solve, becoming to standard problem for new optimization algorithms. For more close to the reality, the kind of TSP that has been chosen in this research is a TSP that contain a penalties for calculation of it tours. Together with increasing of city number that been used, it is more difficult to find the optimal solution. Because of that, a computer program is needed to do that task. Graph representations and heuristic solutions to this optimization are often found using algorithms that are based on what we called “iterative global optimization”. As promising approach, combination of local search and genetic algorithm is used to find the near optimum solutions of TSP, which local search doing it task to find the local optima and genetic algorithm is to find the global optimum (with population-based search).
Unlike the traditional genetic algorithms, which use a single population, in this research for maximizing of optimal solution searching process, the multi population has been used. By using multi population, the search process can go on parallel processing on computer which multi-processor support. To perform multi-population, these research using an approach that based on Genetic Local Search (GLS) with two populations (called subpopulation). In first phase, both subpopulations separately regenerated as like as process on single population. After both regeneration processes completely finish, the process continues with information exchange of that both subpopulations. That process is performed by mate process of two chromosomes from different subpopulation (using crossover only). Although this approach in this research is used only small scale TSP, it can be used for large scale TSP. In this research, the software base on this approach is developing by using object-oriented concept (object-oriented analysis, object-oriented design, object-oriented programming dan object-oriented testing).
Based on experiment result, although the cost of tour can be better by performing that approach but entirely time needed to completely process can be extremely increase. However, with object-oriented concept that has been used, maintenance and development of object and class can be easier and helpful not for TSP purpose only, but it can be applying to other graph problems too (just like minimum spanning tree or shortest path).

You can download my GLS program to solve TSP problem right here.