Dilum Bandara

In queuing theory-based analysis, we always assume arrivals to be according to a Poisson process. "Why we do so, why not it's uniform or some other distribution?" This was a question raised by my supervisor & a colleague while I was preparing for my Qualifying Exam. As I was not able to answer well, my supervisor gave some hints. I was worried that the same question may come up during the exam so searched for an answer on web. Unfortunately, no specific answer was found. So I'm trying to lay down an answer by adding bits & pieces from here & there & my supervisor's answer. It can be answered by looking at the properties of a Poisson Process. Recall that Poisson Processes are used to model statistically rare events. A counting process { N t , t ≥ 0} is a Poisson process if: N 0 = 0 N t has stationary independent increments N t 1 - N s 1 is independent from N t 2 - N s 2 Memoryless Inter arrival times are independently & identically distri...

We fail in many endeavors... But never quit trying... You may succeed either in the same or different area... Even if you succeed in a different area, it because of the previous failure.... Here are some well-known failures that could inspire you...

An interesting presentation by Bryan Lunduke that talks about some of the realities behind Linux & it's future. I do agree that Linux needs a sustainable economic model. All the smart/nerdy developers can contribute while they are teens or while in college. But when you step into real life, you need some serious income. If there is a model that has some economic motives for those developers, we'll have tremendously better software & an OS while enabling those developers to do what they love to do... Slides are available at Bryan's web page.

Finally, the Sri Lankan war is over & everyone is in a single country... I remember the impact of war as far as I remember anything in my childhood... I still remember how windows got scattered & fall down while I was in school due to the JOB bomb (1991). Finally, being able to hear that war is over is a dream come true... Now it's our responsibility to the rebuild the country & make sure people in those areas are taken well care of. Salute to the solders for all forms of sacrifices & president for the leadership...!

I believed that proliferation of Linux affected Sun servers & Solaris lot more than Microsoft Windows... I guess it’s true now... according to the resent news that says “ Oracle to Buy Sun ” Linux enabled the opportunity for low to mid size businesses to run a stable OS on low cost hardware platforms such as x86. So most Sun users eventually migrated to Linux on HP & Dell servers. Though Sun focused more on data centers there may not be successful as IBM or SGI. Anyway, it would be much more interesting when Cisco comes to the server market very soon... Anyway I love Solaris, C/C++ NetBeans, & JXTA though I hate Java... Hope Oracle continues to maintain those...

I had the pleasure of serving as one of the special awards judge during the Colorado Science and Engineering Fair 2009, representing the IEEE Centennial Subsection. I was held at CSU on 9th April. It was amazing to see the type of research projects those junior & senior students had undertaken. Most of the ideas were new, interesting, & had gone through rigorous research methodology. Students had put tremendous effort & spent significant amount of time on those projects. It seems their teachers & parents have given them good guidance & support. It was an honor to meet such a dedicated set of students & talk to them. I’m sure that some of them can even compete with the projects that we do as graduate students… We should try to build the next generation of Sri Lankan students at least like this, that are more open minded, practical, & productive. Wish they have more time to do something that they like, rather than going to after school tuition classes. At leas...

Finally, it seems that Microsoft has decided to do some changes to Vista (I guess the most commercially unsuccessful Microsoft OS release in spite of so much advertising). " Over the past few years, you've asked us to make some changes to Windows. We listened closely, " by Microsoft . Windows 7 is supposed to be faster, more reliable, & easier to do what you want. I would love to have a new OS that combine some of the few cool features in Vista & Plenty of good ones in XP. I hope that they remove the sudden black screen that appears when we try to install a new software, configure a driver or need to allow firewall access. Getting a sudden black screen is scary…. However, other than few minor improvements I didn't see any major improvements. It seems that new interface is becoming more like Mac. Anyway, Beta version is already available for techies to try. Unfortunately, I don't have a machine with 1GB of memory to install. Please share your experience if ...

Microsoft recently introduced Small Basic, a programming language for beginners. It's a strip down version of BASIC with only 15 key words. It seems to be a fun programming environment & definitely worth while trying. You can write both console & graphical interface enabled programs & even develop your own version of Logo. Some of the features include: Its free 15 key words that support basic programming concepts including conditions & iterations Intellisense & context sensitive help Define variables on the fly, no need to explicitly define them Graphic programming Subroutines Third-party libraries can be plugged, API is given It even comes with a simple but comprehensive user guide that introduce basic programming concepts & Small Basic. Though it's intended for beginners, even advanced develops can use it to write scripts that perform simple day to day tasks.

We had a wonderful gathering yesterday. It was the first formal gathering of students & faculty working at CNRL (Computer Networking Research Laboratory). We had food & desserts from around the world. For 7 graduate students, it was a really good gathering which included Prof. Jayasumana, friends & wife's. Visit to my web album for some pictures of the event. Thanks a lot for everyone's help in making the potluck such a great success....

Last week, I attended my first conference in USA. It was in New Orleans, LA. I also presented a paper on VSN formation in one of the workshops (WMSN 2008). It was amazing to see such a large number of participants & parallel sessions on many aspects related to communication. I also met several Sri Lankans from around the world. New Orleans is a nice & interesting city. It is a historic city & has the oldest operational tramcar system. Of course, I went in a tramcar for the first time in my life. It reminded me the old CTB buses that we have in Sri Lanka. My hotel was in French Quarter so had direct access to most of interesting places in town. I went along the Mississippi riverbanks & saw several steam boats. Bourban street is definitely a worthwhile place to experience modern New Orlean's culture. Anyway, it was a nice experience & could have been even better if I didn't had an exam just after I return. See my album .

How to waste time trying to solve a problem that even a child can prove you it can't be done... At least now I want to continue writing on this blog.... I have messed up in the past trying to solve the wrong problem, solve the problem in a wrong way, or trying to solve a problem that can't be solved. So this time I simplify the problem and made sure that there is a answer. But again I failed after 1 week because..... This is what happened...... We were trying to see whether forming a circular link in a sensor network can reduce the overall energy consumption. I did the calculation for a simplified case & figured out it can be done, if two nodes that wants to talk to each other is within a certain angle. Then I tried to solve the big problem by integrating over the whole sensor region. However I got stuck. I then went and talk to my supervisor and discussed about the problem. He said "we don't know whether nodes will follow the shorter or longer path along the circ...

Workshop on Porting Applications on the Computational Grid The workshop was conducted as a collaborative effort from ICTP , SPIDER, & UCSC . Although we got highly competent resource personnel it is so disheartening to see such a bad response from the local research community. I am really not sure the reason for lack of interest. However it may be the feeling among most local scientists that computers can't support there conventional research, "it's not for us...", or "it's for the new generation...". The whole objective of the workshop was to get researchers together & discuss about the possibility (or benefits) of porting their applications (if they already have such applications) to a Grid environment or development of new applications. The infrastructure is already in place & what we need is applications to run on top of those machines. All these are there for the benefit of the country & to the rest of the world. If they don't kn...

IT Day 2006 - Mathara Rahula College Me & Samantha (another lecturer) was invited to deliver a speech at the 'IT Day' of the school. Samantha talked on 'New Trends in ICT' and my one was on 'Technology for a Better Tomorrow'. Samantha was talking about high-tec consumer electronic items, Sensor Networks, Grid Computing, Mobile Robots, new network technologies (WiMAX, CDMA, etc). I presented a case study on HorizonLanka foundation and explained how Mahavilachchiya become the most IT savvy village in the country while enhancing the villages' life through use of ICT. The important aspect about the event was the approach that we used while addressing students. Previous speaker talked on e-Commerce but it was too theoretical & hardly none of the student could understand content, including me. It was a good presentation but suites a more mature audience. The concept of knowing your audience was no there, it was totally outside the expectations of the st...