I am currently running Ubuntu 9.10 AMD64 bit in my Desktop and there are some issues with the warning:

Maximum number of clients reached

Gtk-WARNING **: cannot open display in Ubuntu 9.10 64 bit

After several mins running my OS, I can’t open any program like gedit, VLC, .. even the Terminal. Luckily I still had one terminal left, so I tried to see what the message if I open gedit:


And that message come out. Actually I didn’t know what is wrong with my system even I had a fresh installation of Ubuntu. And this one has never happened before with 32-bit Ubuntu.
[click to continue…]


I have been using Windows for a long time so far. Recently I switched to Windows 7 and was surprised about its performance. The most interesting thing in Windows 7 is that it can automatically recognize the new hardware and install it, so I didn’t need CD driver for installing drivers like I did before. I am a Linux fan, but I still use Windows because I am using some particular softwares that run only in Windows.

But actually it made me crazy with the default sound driver, I couldn’t enjoy great sound like before in Windows XP. Searching in the Internet and found out there are a lot of people out there got the same problem like have no sound, there is crazy noise, … and there are also a lot of solutions. But the easiest way is use the default drivers provided by the manufacturer.

Step 1

Uninstall the old driver from Drive manager by typing those words in the search box, find sound and uninstall it.

Device manager

Step 2

Use the driver disc and find audio folder under audio and install it. After that, restart the system again. The audio driver in here is Realtek High Definition Audio Codec R2.04 (09/12/2008).

You can download that driver from here or simply search that version driver from Google.

Note: not the latest version because I have tried it and the same problem had occurred, so be careful.


This post, I would like to introduce about the HapticMaster just like a summary about the paper I have read: The HapticMaster, a new high-performance haptic interface

What is the HapticMASTER ?

As you can see from the above picture, the HapticMASTER is a 3 DOF device designed by FCS company and there are 2 dedicated industrial computers for a inner controller and a outer controller. Both of them use VxWorks real-time operating system.

haptics master 1

The end effector plate workspace of the HapticMaster spans a 3-dimensional space with a volume of approximately 80 liters. The end plate of the robot arm allows the mounting of difference end effectors.

haptic master actuators

Controller of HapticMASTER

The HapticMASTER is a force controlled haptic interface:

  • Input: force from the human
  • Output: the proper displacement

It means when a human pushes the hand, by using the force sensor the device can measure an exact force, therefore give the proper displacement. So simply called: force in and displacement out. It is a Admittance control.

haptic controllerThere are 2 controller which are inner servo loop and outer control loop. I just take an explanation from the paper:

The HapticMaster measures the force exerted by the user, preferably measured close to the human hand with a sensitive force sensor. An internal model then calculates the Position, Velocity, and Acceleration (PVA), which a (virtual) object touched in space would get as a result of this force. The PVA-vector is commanded to the robot, which then makes the movement by means of a conventional control law. The general control algorithm is illustrated in Fig. 2. The internal model will typically contain a certain mass, to avoid commanding infinite accelerations. The inner servo loop will cancel the real mass and friction of the mechanical device.

An other interesting thing is two loops of the controllers run at a fixed update rate of 2500 Hz, which is approximately ten times higher than the maximal human discrepance value [Burdea, 1996].

There are some examples people in some laboratories did with HapticMaster:

YouTube Preview Image

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Qt 4.6 and Creator 1.3 have been released

2 days ago, I received the newsletter from QT that QT 4.6 and Creator 1.3 has been released, please check it out to see the new features.

Before, I have used QT Creator 1.3 beta, but I feel it had been improved so much compared to the previous version.

Qt 4.6 & Qt Creator 1.3 Out Now!

Nokia has released Qt 4.6, the latest version of the cross-platform application and UI framework. Featuring new platform support, powerful new graphical capabilities and support for multi-touch and gestures, Qt 4.6 makes developing advanced applications and devices easier and more enjoyable.

More Platforms

Qt 4.6 includes support for the Symbian platform for the first time, and also adds Windows 7, Apple Mac OS 10.6 (Snow Leopard) and the upcoming Maemo 6 to the list of Qt supported platforms. Also available is community support for real-time operating systems QNX and VxWorks. Support for Maemo 5 is also currently in development, with the second technology preview being released today.

Get informed and find out what’s new in Qt 4.6:



Follow Qt 4.6The Qt Blog

YouTube Qt Studios Channel

Check out our Qt 4.6 demos on multitouch and gestures, Qt on mobile platforms, Symbian, Maemo and find out how Qt 4.6 defeats the master of poor application development in our feature presentation of Qt-Feratu! Qt Studios Channel

Spotlight on Qt in Use MIDs & Netbooks
Qt allows for cross-platform development making it attractive for MID and netbooks manufacturers who need to offer unrivaled features and applications. In addition to offering a toolkit which eases application development , Qt SDK allows OEMs to develop their own SDKs for 3rd party development.
Find out more.


Tutorials how to work with Drupal

I took those tutorials for Drupal website since I am studying how to use Drupal and how to customize it to my Group website. I think that will be useful for everyone who are using Drupal as beginner, even for the professional Drupal person.

Part 1: Introduction and overview

July 2006
This first article introduces the business scenario and describes the factors that drove the Internet Technology Group team to choose open source tools and Drupal over other content management systems available today.

Part 2: Design for an effective user experience

July 2006
Follow along as the Internet Technology Group team redesigns an existing Web site, analyzing business goals and users’ goals, evaluating the existing site, and iteratively refining alternative solutions based on user feedback.

Part 3: Building your development environment in Windows

August 2006
Install and configure in this tutorial all the software necessary to develop a Drupal-based Web site in Windows, including Eclipse, PHP, and more. When you’re done, you will have a blank development canvas that you can use for any development project.

Part 4: Building your development environment in Linux

August 2006
Install and configure in this tutorial all the software necessary to develop a Drupal-based Web site in Linux, including Eclipse, PHP, and more. When you’re done, you will have a blank development canvas that you can use for any development project.

Part 5: Getting started with Drupal

August 2006
Learn about the Drupal programming model used in developing Web sites, and explore different types of content, developing new features using modules, implementing hooks to enable those modules, and site URL design.

Part 6: Building a custom module in Drupal

September 2006
Create a custom Drupal module for announcements. Learn about implementation and use code samples to create your own custom module.

Part 7: Structuring content for theming using XHTML

October 2006
Explore methods to structure content delivered by Drupal during the development of a new extranet Web site.

Part 8: Styling content for theming using CSS

October 2006
Learn methods for structuring the content of a new extranet Web site, including how to change the presentation and styling of the content delivered by Drupal.

Part 9: Understanding the database layer

October 2006
Discover best practices for module developers. Get details about using the Drupal database functions. And implement the necessary code to support a new database — IBM DB2® Express-C.

Part 10: Adding features for an extranet Web site

November 2006
Define an extranet to meet client requirements and explore implementation techniques to create an extranet Web site.

Part 11: Using taxonomies in Drupal

December 2006
Use the taxonomy system in Drupal to provide structure to your Web site, which in turn helps support navigation and organization of your content.

Part 12: Hosting and deployment

December 2006
Investigate the issues surrounding deployment of a Drupal site using virtualization technologies. Find out why the team opted to go with virtualization in this scenario and which hosting options you should consider for your own Web site.

Part 13: PHP development within Eclipse

January 2007

Use the Eclipse integrated development environment to create your Web site, with a focus on Eclipse’s support for PHP and using Concurrent Versions System (CVS) for version control.

Part 14: The announcement module source code

March 2007
Get the complete announcement module that is used as an example throughout this series. All the functions from this module are included and can be downloaded in a single file.

Part 15: Lessons learned and what’s new in Drupal

April 2007
You’ve completed the process of developing a Web site using open source Drupal driven by Apache, PHP, and MySQL. Find out which decisions and approaches worked or didn’t work for the team, and the latest in Drupal 5.0.

Source: http://groups.drupal.org/node/10683