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Scott Roepnack :: Blog

August 16, 2009

Dr. Huang Arrival

Dr. Huang, my advisor from Florida arrived in Beijing a few days ago.  She is originally from China an came back for about a month to see family, attend a conference, and of course she squeezed in a little time Adriana, Jake and myself.  We spent a few days in various meetings, updating her on our progress and showing her where we wanted to go from that point. 

For my project in-particular, Dr. Zhang, Dennis and myself felt that we did not have enough time to complete our proposed research.  The three of us and Dr. Huang together found a way to narrow the problem space of the project.

The narrowed down problem space would focus on the similarity function, the first step in the recommender process, and on hybrid recommenders that utilized tag information.

After the project work was scheduled out for the next few weeks, Dr. Huang took us to BeiHang University.  We met with some of her friends who are professor at BeiHang University.  The main goal of the meeting was to get “the ball rolling” so that next year students in the PIRE program could also perform research at BeiHang University and Tsinghua University.


Tian Jin

On August 2nd, Liu a student that Jake has been working with took us to Tian Jin.  The city is about 150 kilometers from Beijing, we took a bullet train to get there, traveling at 330 km/hr.

Many of the chinese that we have been working with at Tsinghua University told us that we had to try a special type of dumpling in Tian Jin, called Go Bu Li (Dog’s Don’t Care).  Don’t worry the dumplings were not filled with dog, its just a name.  The dumplings were wonderful, the second best we had our whole trip, second only to the dumplings in Xi’an.

We only spent a few hours in Tian Jin, but it was a great experience, it was defiantly the place to go and try a type of Chinese food.  The food in Tian Jin was sweeter than the food in Beijing, which was a nice difference.  I definitely recommend spending a day in Tian Jin to the students who go to Tsinghua University next year.


Words of Wisdom/Suggestions

Buy a bike ~¥120-200

Get a multipass/multiuse public transportation card at any subway station

Be ready for spicy food

Be ready of cold food being almost nonexistent

lots of bargaining

Helpful Websites

Laundry in building 18

Take some Mandarin lessons, it really helps

Bus 731 is right outside the foreign dorms at Tsinghua University, one stop will take you to Wu Dao Kou

Things I loved about China

The Food - its nothing like the Chinese food we have in America

The Summer Palace

The Great Wall - Mu Tan Yu

Public Transportation - Cheap/Get Anywhere

Things I didn’t expect about China

Lack of paper towels/napkins

The pollution wasn’t as bad as I thought it was going to be

Kindness/Giving nature of the chinese people

Diversity of food/people/languages

Everything is huge and colorful

Things to pack (that are hard to come by in China)

Peanut butter

Oat meal

Gatorade powered 


Sites To See in Beijing and Xi’an


The Summer Palace

The Great Wall - Recommend Mu Tan Yu area

The Temple of Heaven

The Forbidden City

Hou Hai

Beijing Zoo

Beijing Aquarium

Beijing Planetarium

SIlk Street

Beijing Acrobat Show

Food Market - anything on a stick

Tian’amen Square

Mao’s Tomb

National Museum of the People

Computer Market

Olympic Green/Birds Nest/Water Cube


Xi’an (By Over Night Train Z19/Z20)

Terra-cotta Soldiers

Bell/Drum Towers

Da Fu Chang Dumplings (Third Floor, not the dumpling restaurant on the first/second floor)

City Wall

Tang Dynasty Show


Project Current Status

Enhancing Similarity Measurement by Utilizing Tags in Item-Based Collaborative Filtering


In Item-Based collaborative filtering, there are many steps employed to predict the user's interests on various items. Similarity measurement is the first step of the process and influences the accuracy and precision of the final recommendation.  The existing similarity measurement methods rarely utilize user defined tags to assist in analyzing how homogenous items are in the eyes of users.  This paper aims to enhance the similarity measurement by combining traditional item-based collaborative filtering with tags.  The process will follow three steps to calculate the similarity measurement. The first step is to calculate the similarity measurement only using weighted tags. The second step is to calculate the similarity measurements by using item-based collaborative filtering techniques, such as, Pearson Correlation, Cosine similarity, and Spearman ranking. The final step is to combine the results from the previous two calculations and continue from there with traditional item-based collaborative filtering, for example, nearest N neighbor and prediction techniques.  We will then compare the prediction results using only traditional similarity measurement and our redefined similarity measurement.

Keywords: Huang, Suggestions, Tian Jin, Tsinghua, Words of Wisdom

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July 12, 2009

Last friday Jake and I traveled from Beijing, China to Xi’an, China.  Xi’an was the original capital of China.  The city of Xi’an has a history that goes as far back as the pyramids of Egypt.  When we disembarked and exited out of the train station we were directly outside the north gate of the city wall.  The City Wall surrounds what used to be the entire city of Xi’an, now of course the city has expanded. 

As we walked past the very long corridor, the walls made of people, all holding signs with people names.  A man named Peter approached as and asked if we needed some help.  It was apparent obvious that he was going to try and sell us something, we stood out like sore thumbs.  Not knowing our way around I thought I would use this as an opportunity to find out as much information as I could about the area, Peter spoke well enough english, and as kind.  He was quick to mention the company he works for, a tour service, and offer us a ride to out hotel, of course for a nominal fee.

We hadn’t purchased our return tickets, so thats where we went first, the ticket office was on the other side of the train station and Peter showed us the way.  After buying our tickets Peter took us to our hotel for 20 yuan, a little more than three dollars.  This was the first time we used what is known as a “black taxi,” which just means an unregistered taxi.  They are very abundant here in China, and for the individuals coming next year, a good tip on the procedure using the black taxi is to agree on the price before you get in, have the exact amount of cash with you, show the driver the money, get him to nod in agreement, and keep the money in your hand during the drive, if the driver attempts to give you a hard time, you won’t have to go back into your wallet or bag.  Since Peter was trying to sell us tour tickets I knew we would be okay on the drive to the hotel.

When we arrived, we were warmly greeted by the hotel bell-boys.  The check-in procedure was simple enough, and the room was wonderful.  The concierge helped us get tickets to a Tang Dynasty dinner and show, as well as, a tour of the Terra-Cotta Warriors tombs.  

It was only about noon, so we sent out to explore Xi’an.  We got a taxi and went to the city center.  Two of the main attractions of Xi’an are the Bell and Drum Towers.  These towers are now filled with many artifacts, and are small museums, but they were used for more practical purposes in ancient China.

We walked south along one of the main roads in Xi’an towards the city wall.  We went up the wall and rented a two person bicycle.  Neither of us had ever ridden a two person bike and it was a lot of fun, we biked around the entire city wall, which was a great experience.  

After biking around the wall we headed further south, for the Tang Dynasty dinner and show.  The Tang Dynasty was the pinnacle of music and art here in China.  The dinner and show was a wonderful experience.  The food was probably one of the best meals I’ve had.  The show was good except for one instrument, which sounded like a high pitched bird sound.  Luckily, that instrument was only in one act.

On Sunday, we took a tour to the Terra-cotta Soldiers tomb, which was another awesome experience.  Our tour guide took us to the location where they are recreating the terra-cotta soldiers in the same way that they were originally made.  After which we went to see the actual museum.  Most of the soldiers were destroyed many years ago, however, they have reconstructed the soldiers from the broken pieces.  Kind of like the hardest jigsaw puzzle imaginable.

Our next stop on the tour was the hot springs.  Which I do not recommend to the people who visit Xi’an.  It was really boring.  For some reason I had imagined a gizer, like in yosemite national park.  However, it was nothing like that.  Basically just small puddles of water...  Maybe it was the time of year we went, but it really wasn’t anything worth seeing in my opinion. 

All in all our trip to Xi’an was great!



Keywords: China Trip, Xi'an

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June 29, 2009


Here at Tsinghua, and in the surrounding areas the best way to get around of course is a Bicycle.  Everyone has at least one.  Anytime we leave our dorms the trip usually starts with a bicycle ride, and of course there may then be transfers through buses or the subway.

I’ve been involved in a “Bike-Jam.”  This is kind of like a traffic jam everyone knows with cars, but with bikes.  It didn’t last long but it was quiet a funny experience looking back on it (wish I had my camera with me).

Theft!  So far we have been lucky our bikes haven’t been stolen, even though they only have one lock each.  Yep you read that right.  When we first got here all our chinese colleagues asked “how many locks do you have on your bike?”  Many people here put more than one lock on their bike, because a thief will be less likely to pick the bike with more than one lock.

Some things we’ve been told about bikes here at Tsinghua:

“You may have received your student registration papers but, you are not a Tsinghua University student until your bicycle is stolen.”


A new student came to Tsinghua University, bought a bike and one lock.  His bike was stolen during the first week of classes.  So the student went and bought another bike, this time with two locks.  Sadly, that bike was also stolen.  Realizing it was impossible to get around Tsinghua without a  bicycle, the student went and bought a third bike, this time with three locks!  One day after classes the student returned to his bike, and saw that another person had put their lock on his bike!


A friend of Michael’s said, she had 6 bikes stolen from her during her undergrad.


How to park your bike, oh yes their is some thought that goes into this as well.  Do not park your bike by itself.  Do not park your bike on the end of a row.  Try to find a spot that will leave the least amount of room between your bike and the bikes next to yours.  If you don’t think that’s enough, try and park your bike next to a bike that looks new/nicer than yours.


Keywords: Bicycles, Bike, Public Transportation

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The Beijing Zoo was a wonderful experience.  The zoo has been here for over 100 years.  The vast amount of animals was amazing.  Everything from Pandas to Elephants and even *drum roll* The Common American Raccoon.

We spent a whole day at the Zoo the highlights included in no specific order:

  • Pandas (we counted 10)
  • Nocturnal Animals 
  • Elephants
  • Hippopotamus
  • Lions
  • Tigers
  • Giraffes
  • Penguins
  • Lots of Snakes and other Reptiles
  • Golden Monkeys
  • Apes
  • Kangaroos 
  • Lots of fish in the new Aquarium which is huge
  • Dolphins
  • Sea Loin
  • Octopus
  • Jellyfish

These are just a few of the awesome sites to see.  The tour guide booklet we had said this was doable in just a few hours, but we can’t see how that is possible, if you actually want to see a good portion of the animals.

While at the Beijing Zoo we ran into a very unique door, I bet a few of you might get the reference, see the picture below.




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June 23, 2009


What: A system that will predict items that human users will prefer over other items, based on  previous ratings by both that specific user and other users that have similar tastes.  These groups of human users form neighborhoods, and it is expected that users in the same neighborhood will react similar to the same stimulus1.  

Rather than doing this from the user perspective, we are going to look into doing this from the item perspective because, in general, you will have a larger number of users than items, or at least a more variable amount of users than items.  In addition, rather than just using a Collaborative Filtering scheme we will combine this methodology with other forms of filtering to create a hybrid system.  The other schemes we are considering at this point are: Content, Knowledge, Utility, and Demographic Based.

By  combining Collaborative Filtering with another scheme we intend to eliminate the problems associated with it.  Such as the, Ramp-Up, Grey-Sheep, and Stability vs. Plasticity problems4.

Why: Over the past several years the amount of data on the internet has increased dramatically2.  Searching through the enormous amounts of online databases can be time consuming.  We believe that utilizing past information from users will allow our algorithm to predict what items a user needs or wants, thus we will be able to recommend items so that the user will not have to search online databases.

Example: John may watch movies online.  Over time he rates a few movies, which will put John into several neighborhoods.  One of the neighborhoods maybe a niche of drama movies.  So the system may predict that John would like the movie Titanic, because many people who like drama movies enjoyed this movie.  One thing to consider here is if John likes the movie and rates it highly then the system actually has not learned a lot of information about John, because it already knew he like a niche of drama movies.  However, if John rates Titanic poorly, then the system can narrow down his likes and dislikes even more, because he has shown he is not in the main “drama” neighborhood3,4.

  1. A User can be in several Neighborhoods simultaneously  
  2. World Internet Users and Population Stats - http://www.internetworldstats.com/stats.htm
  3. In actuality neighborhoods will not be broken down based so heavily on genre, but for the example it is used to convey the idea of a neighborhood.  Neighborhoods will form over time based on users input of items, meaning Neighborhoods form dynamically at and during run time.
  4. Hybrid Recommender Systems: Survey and Experiments http://www-mmt.inf.tu-dresden.de/Lehre/Archiv/Sommersemester_04/Hauptseminar/papers/burke2002.pdf

Keywords: Recommender Systems, Taste Framework

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June 21, 2009

Last weekend after seeing the Olympic Park we continued on our subway trip to UIBE (University of International Business and Economy).  Jane, a student at UIBE met us at the subway station near the University.  

The University was not as big as Tsinghua, but it was very beautiful.  With a nice grassy park right in the center of the campus.  UIBE has the biggest dorm in all of Beijing (we were told) the building held 500 students per floor... and there were 10 (maybe 12 can’t remember which at this point).  So either 5000 or 6000 student in one building.

It took about 20 or 30 minutes to walk around the campus, then we went to dinner.  We walked about 5 minutes from campus and we entered a small alley with a few red lights.    At this point I realized that all the best restaurants in Beijing are down an alleyway and up 3 flights of stairs, the kind of ‘hole in the wall’ places most foreigners probably would think of going into.  Yes the food was great!

After, dinner Jane showed us around a park near her school, it was dark and peaceful.  A nice break from the hustle of day-to-day.


Keywords: UIBE, University of International Business and Economy, Weekend Trip

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June 19, 2009


Sorry I haven't posted in a bit, I’ve been rather busy this week, but that means I've got some blog post ideas piled up, so please put your tray tables and seats in there up right and locked positions!

Last Sunday, Adriana, Jake and I, used the subway by ourselves for the first time.  We were able to buy a multi-use passes.  Waiting in line to buy a ticket every time we wanted/needed to ride the subway would of been a pain.  And there is a bonus!  The card also works on the buses here in Beijing, woohoo!

The three of us were going to meet a friend of a friend, whose english name is Jane.  She studies at UIBE (University of International Business and Economy).  The subway was very easy to figure out, everything is in both Chinese and English.  The cost of the subway is 2 RMB for each ride, and you can change subways as many times as you want, without paying again.  So that's about 30 cents, for each subway trip.

We left ourselves a lot of extra time, over 2 hours, because we just had time to kill, and figured we could check out the area around UIBE.  On the subway however, Jake noticed that we could go the "Olympic Park," if we changed trains.

So we did, we came out of the subway about 3/4 a mile from The Bird’s Nest and The Water Cube.  Both we extremely big, just like everything here in Beijing.  After going through 2 security checks, and probably one of the widest bridges I’ve ever been on, we got up close to the Bird’s Nest.  We didn’t go inside of either of the buildings, we wanted to save that for when Michael arrived.  However, the courtyard between the two buildings was amazing too, there was lots of art, and people.  Looking at the courtyard I could imagine it filled during the 2008 Olympic Games.  

It was an amazing site to see!


Keywords: Bird's Nest, Olympic Park, Subway, Water Cube, Weekend Trip

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June 16, 2009

On Friday one of the students in Adriana's lab asked us to go Hiking with a hiking group that he is apart of.  We took the subway as far north as we could, then we took a bus ride even more north for about 40 minutes.  At the base of the mountains is a man-made dam, it was built by one of the emperor's of China, it was very beautiful.

We took the "local way" up the mountain.  The path was very steep in some places, the three of us (Adriana, Jake and I) realized just how out of shape we are.  Maybe its the fact that we are used to sea-level air, but anyway, we took several breaks on the way up.  About half way we stopped for lunch.


When we finally got to the top the view was wonderful!

On the way down we took the "tourist way" which involved some areas with man made steps.

By chance we ended up passing a Garden with zodiac animals.

When we got to the bottom of the mountain we found a section of the mountain that had been craved out with some Olympic Symbols. 


All in all the the mountain was a wonderful day trip, even though it was extremely exhausting, who would of thought I would get to climb a mountain in China, with such wonderful people!

Keywords: Day Trip, Mang Mountain

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June 11, 2009

Everyone we have met so far has been extremely kind, helpful, and patient.  The other morning Adriana, Jake and I were riding our bikes to the lab, we decided to take a different route because it had more tree and shade.  About half way down the ride i wanted to check the map to make sure we were going in the right direction.  We stopped and I pulled out my map, as I did this I noticed a man running down the street towards us, he pasted us, and kept running.  This is not an uncommon thing to see.  I started looking around and at the map to figure out where we were.  The person who had run by about 20 second before came walking back to us, and in very good english asked if we needed help.  I said we were trying to figure out where we were and he looked at the map for a second and pointed to a location.  We thanked him.  Immediately after he took off running full speed in the direction he was originally going.  

Before coming to China friends of mine (Mary and Evi) introduced me to a friend of theirs (Yinghui).  She was in the USA for a year from China.  They had become good friends, and taken Yinghui around Florida, and to other places during her stay in the US.  So they thought they she would be willing to return the favor, kind of a cultural exchange.  Sadly she wasn’t returning till after my time here is over, but she was able to contact some of her student and put me in touch with them.

Adrian, Jake and I met with Jane (one of Yinghui’s students) and her boyfriend Thursday night.  Jane is of course her english name.  She attends the University of International Business and Economy, majoring in Finance.  The five of walked a little bit outside of Tsinghua University, and had a wonderful dinner.  After dinner they showed us the bus stop near the University, and which bus to use to get to the Summer Palace.  They also showed us where the nearest subway station is, and a movie theater.  We picked up a very nice map of beijing and spent about 20 minutes marking it with places to go, and how to get to each one.

People have gone out of their way to help us, these are people who don’t know us at all or have very little connection to us.  I hope that most people experience China from this perspective.

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It’s amazing some of the difference between the USA and China.  Personal space is one thing that is just different over here, I wouldn’t say better or worse, just a cultural difference.  People tend to be closer together here.  The other day there was a class on the basketball court, and they were literally shoulder to shoulder with each other.  Now you might say, “well basketball courts aren’t the biggest things... I could see people like that here in America too.”  There are about 15 full sized basketball courts right next to each other, and at the time this happened they were the only group of people out there.  The story doesn’t end there, at the time we were on our way to go shopping, it took maybe 20-30 minutes.  On our way back, they were in the same spot, in the same order, still listening to the coach.

I can see why its like this though.  Beijing and China a like are very heavily populated places, so the Chinese people grow up constantly surrounded by a large number of people.

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