Saurav R. Tuladhar

My own musings

Provincetown visit

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Provincetown harbor from the High Pole Hill

After living in the Bay State for the last eight years, I finally visited the famed Provincetown during the Memorial day weekend. Provincetown (also locally called the P-town) is located at the tip of the Cape Cod region in Massachusetts. One can get to the P-town either by driving via US Route 6 which goes all the way to the town. But during a busy weekend, you are highly likely to get stuck in heavy traffic before you can even enter the Cape Cod region. So in order to avoid the ‘cape traffic’, we decided to take a ferry ride from Boston to Provincetown.

The Boston Harbor Cruises ferry ride was $88/person (roundtrip) and took about 90 minutes each way.  The ferry leaves from Long Wharf in Boston. If you are planning to do a weekend one day trip to the P-town (as we did) and looking for a parking, I strongly recommend the Post Office Square parking garage. It is only about 10-15 minutes walk from the garage to Long Wharf and the weekend fare is only $9, which is significantly cheaper compared to other parking lots nearby. Our morning ferry was at 9 AM, so we arrived at the parking garage around 7:30 AM and had plenty of parking spots.

Provincetown engraving

The ferry left the Long Wharf sharp at 9 AM and arrived at the Macmillan Wharf in Provincetown at litter after 10:30 AM. A warning, during the first 30 minutes of the ferry ride out of Boston, the sea was rough enough to cause sea-sickness to several passengers including us. The ferry crew were giving out paper bags incase somebody threw up.

From the Macmillan Wharf, it is a short walk to the Commercial Street which is the main thoroughfare of the town. There are lots of shops along the street and tourists like us walking about. I was surprised by how narrow the street was, but it makes sense give the time when the town was established. We arrived early enough that there weren’t too many people on the street (yet!), so walking around Commercial St was fun enough.

As you get of the ferry and walk towards the town, it is hard to miss the Pilgrim Monument  tower, which is the tallest structure in the town. We decided to visit the monument/museum where the entrance fee was $12/person. You can climb up the tower on foot. The climb is a combination of stairs and inclined flights. It must have taken us about 20 minutes to get to the top. But the views of the harbor and the town from the top are well worth the climb.

I also learnt that the monument was erected to mark the arrival of the Pilgrims, the early European settlers, in the Provincetown in 1620. The common belief around is that the Pilgrims first make landfall in Plymouth, Massachusetts. But it turns out that the Pilgrims actually landed in Provincetown and docked their ship, the Mayflower, in the harbor for a week before departing for Plymouth.

Pilgrims Monument

By the time we returned from the monument, and  wen to the Commercial St for lunch, the street was full of people. So after grabbing lunch, we ventured out of the town towards the shores. Crowd filled Commercial St can feel a bit suffocating, but as you move away from downtown and approach the shores the cape surrenders its most intimate natural beauty to its visitors. The Cape Code region has a distinct outlook due to it geography. I have noticed this ‘capey feeling’ every I visited the this region. The Provincetown shores were no different. Its rustic mixed with the constant sound of waves hitting the shores. All this is very relaxing.

Quintessential cape

Quintessential cape

We reached the Herring Cove beach, which is about 1.5 miles west of downtown. The beach crowd was not there and the water was still freezing cold. But still the Sun was warm enough to enjoy the late afternoon basking. After spending about and hour in the Sun and walking along the shoreline we headed back to the hustle and bustle of the Commercial St.

Herring Cove Beach

Our return ferry was scheduled for 8:30 PM and this time of the year the days are long and the Sun sets around that time. Just before our ferry departed, P-town treated us with this glorious sunset view leaving a lasting memory of the trip.

Pilgrims Monument

Written by Saurav

June 3, 2017 at 10:14 AM

We choose to go to the moon

We choose to go to the moon in this decade and do other thing not because they are easy, because they are hard, because that challenge is one that we are willing to accept, one we are unwilling to postpone and one we intend to win. -JFK

Written by Saurav

August 23, 2016 at 7:18 AM

Posted in thoughts

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Resources on Kalman filters for tracking applications

For the last couple of months, I have been working with Kalman filter and its variations for aircraft tracking applications. I have found following resources helpful in the course of learning about Kalman filters.

Estimation with Applications to Tracking and Navigation: Theory Algorithms and Software , Y. Bar-Shalom; T. Kirubarajan; X. Li

Prof. Y. Bar-Shalom is well known in the area of tracking applications. This book by Bar-Shalom and co-authors is the standard text book for anyone interested in learning about applying Kalman filters. The authors aim to “make things simple, but not too simple; clear but not too clear“. The book not only presents theoretical derivation of filters, but also discusses implementation details. I have found the discussion on practical issues extremely helpful in the course of implementing the filters myself.

Kalman and Bayesian Filters in Python

This is a book by Roger Labbe. This book covers a wide range of topics related to Kalman filters and its applications with focus on practical applications. What I liked about this book is that the entire book is composed as a Jupyter notebook. As a result, Roger not only presents the mathematical background but also presents code implementation of the filters. FilterPy is the accompanying python package which provides implementation of all the filters discussed in the book. If you are interested, it is straight forward to change the sample code in the chapter notebooks and see changes for yourself. This book is a fine example of literate programming.

 

Written by Saurav

August 14, 2016 at 7:35 PM

Posted in Uncategorized

Unit circle MVDR beamformer for ICASSP 2015

I recently traveled Brisbane, Australia to attend the 41st ICASSP 2015 where I presented the poster on the unit circle MVDR beamformer. The accompanying paper should be available on IEEExplore soon. For now, I have made the pre-print available.

My submission for the upcoming ICASSP 2015 has accepted for presentation (Yay!). Following is the abstract of the accepted paper

The array polynomial is the z-transform of the array weights for a narrowband planewave beamformer using a uniform linear array (ULA). Evaluating the array polynomial on the unit circle in the complex plane yields the beampattern. The locations of the polynomial zeros on the unit circle indicate the nulls of the beampattern. For planewave signals measured with a ULA, the locations of the ensemble MVDR polynomial zeros are constrained on the unit circle. However, sample matrix inversion (SMI) MVDR polynomial zeros generally do not fall on the unit circle. The proposed unit circle MVDR (UC MVDR) projects the zeros of the SMI MVDR polynomial radially on the unit circle. This satisfies the constraint on the zeros of ensemble MVDR polynomial. Numerical simulations show that the UC MVDR beamformer suppresses interferers better than the SMI MVDR and the diagonal loaded MVDR beamformer and also improves the white noise gain (WNG).

 

Written by Saurav

March 14, 2015 at 9:53 PM

Phase of product of complex-circular Gaussian random variables

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What is the distribution of the phase of the product of two independent zero-mean complex-circular Gaussian random variables? I try to answer the question in this IPython notebook.

Written by Saurav

March 14, 2015 at 9:49 PM

Data Science from Nepal

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Data Science from Nepal

Its hard to miss “Data Science” or “Big Data” as the two hot topics at present. Wikipedia defines data science in the simplest terms as the science of extracting knowledge from data. The vast potential of data science applications is driving the job market and proportional investment from big companies. Consequently startups working in the area of data science ahave been mushrooming around the world.

Nepal hasn’t remaind untouched by the growing interest in data science. I have been following a string of startups from Nepal working in data science. These are exciting times for startup scenario in Nepal, and it is encouraging to see people experimenting with data science in their startup venture. Here I am listing some startups that I have been following:

  • Oval Analytics – Your Data Science Partner

    Oval Analytics is the brainchild of Hemanta Shrestha and Saurav Dhungana. Oval is perhaps the first technology company in Nepal with aim to provide data analytics services to local clients in addition to external clients. This is a challenging task given the limited market within the country. Oval Analytics wants to become an important part of the data science community in the country.

  • Data Nepal – Nepal Unleashed

    DataNepal was a startup with an aim to become the goto repository for “socio-economic, demographic, environmental, developmental and geospatial data “ related to Nepal. The data was mainly collected from public domain and made available in more friendly formats (JSON, CSV, XML).

  • Graph Nepal

    Graph Nepal is perhaps the first startup with focus on data visualization and infographics focused on local issues. Visualization is a powerful part of conveying the story based on big data analytics.

  • Kathmandu Living Labs
  • Cloud Factory

Let me know @sauravrt, about other startups from Nepal who are working in the area of data science, analytics and visualization. I’d be happy to know more of them and add to my list here.

Written with StackEdit.

Written by Saurav

February 8, 2015 at 3:41 PM

Posted in Blog

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DC Visit

View of the Lincoln memorial

I recently visited Washington DC, the country’s capital, with my wife and some friends. It was a three day visit over the Memorial day weekend. This was my second time in the capital. A combination of perfect weather and good company made this a memorable trip for us.

Preparation
Travel: Our plan was to drive all the way to DC. On a normal traffic it should take us around 8 hrs to reach DC from Boston. We rented a car big enough to fit six people. We had three of us who could share the drive. Also we planned to use Waze app and Garmin GPS with live traffic to keep our eye on traffic condition ahead.

Rented car

Lodging: We decided to try out Airbnb for our stay in DC. After couple of days of collaborative search we were able to find a host who would take in six guests. The host had good reviews from previous guests and place was located behind the US Naval Observatory . So we felt pretty confident about the host and neighborhood.

Day 0 ( May 23, 2014)

The reservation for the rented car had a pick up time of 12 pm, but a call to customer service early in the morning confirmed that we could pick up the car earlier. So three of us who would be driving set off towards the Logan airport where the rental car was located. After quick negotiation we were able to get a slightly bigger car (Chevy Suburban instead of Tahoe). On the hindsight we are glad we made that choice. The Suburban was plenty spacious of six people and had enough luggage space too.

We drove back to our apartment where we loaded our luggage onto the car and by 12 pm we were on the road. Our plan was to head out by 12 pm so that we would reach DC by 9 pm in the evening. So we were pretty pleased with our organization. We took I-90 W all the way to Sturbridge and split off to I-84 to head down south. We were worried that we would hit New York City evening rush hour traffic.

 

Written by Saurav

June 1, 2014 at 9:04 AM

Posted in Travel

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