Me and my Nikon D40 were out to capture the beautiful wild flowers of Prenzlauerberg. Here are a few samples from the excursion.
Sunday, May 25, 2008
Wildflowers in the Prenzlauerberg spring
Me and my Nikon D40 were out to capture the beautiful wild flowers of Prenzlauerberg. Here are a few samples from the excursion.
Wednesday, May 21, 2008
Finally, the "Net" in Netflix; plus, the bandwidth question
Netflix has released a set-top box that users can use to receive movies directly over their broadband Internet connections. The box, developed by the silicon valley company Roku, has received good reviews on CNET and PC Magazine for its nice interface and more-or-less good performance over most home-broadband connections.
Advantages for users
The Netflix system delivers video streams at 2.2 Mbps, 1Mbps, and an even lower bit-rate depending on the connection between the server and the receiving box. The quality naturally degrades according to the lessening bitrate, but let us assume that a user has a great Internet connection and that no bandwidth bottleneck exists between the serving CDN and this user and so s/he can watch the best 2.2Mbps quality for the entire 120 minutes of a movie.
Size of the movie:
2.2 Mbps x 7200 seconds (i.e. 120 minutes) = 15840 Mb = 15840/8 MB = 1980MB = 1980/1000 GB
= 1.98 GB.
So downloading a movie at the best quality means the CDN serves about 2GB of data to the end-user's Netflix- Roku box.
To arrive on the bandwidth costs, lets go with the figures presented in this PBS article about CDN pricing. Disclaimer: This article is more than a year old, and I have been reading about CDN price wars all along. So the current cost of bandwidth may actually be lower than stated.
From the PBS article the costs for streaming a 2GB stream to a user (assuming volume wholesale pricing):
Ok first off, I like the P2P number the most but lets ignore that because P2P may not be able to compete in quality with CDNs (See my paper on this). Even if Netflix uses the most expensive Akamai CDN, they are getting away with just $32 cents per movie instead of the dollar-plus cost in the DVD-mailing model. Even if we assume a few more cents of overhead per movie due to the technology costs, I think Netflix is well in the green with this.
The beauty of Netflix's strategy is that they will be able to gradually wean people from the DVD mailing model to the this online content delivery model because of the convenience of the latter. And this without jeopardizing the DVD mailing model because there is no cannibalization here - its perfect migration with one less DVD mailing customer corresponding to one more streaming customer. Every DVD streamed will add up and lead to a drastic reduction in Netflix's operating costs.
Meanwhile, Roku will probably make some money out of their $99 box.
Last question: And the ISP?
Thats for later. Enjoy your movies.
Update: Netflix bandwidth costs come to about $5cents as of June 2009, according to this article.
Advantages for users
- No propagation delay from snail-mail shipping DVDs - no more waiting for 2 days.
- No need to mail back DVDs.
- Ability to switch to another movie or show - you are not stuck with that wrong movie you placed in your Netflix queue.
- No extra cost except the broadband connection and the $99 cost of the box.
- Savings in storage, handling, and shipping costs (to-and-fro) of the DVDs. Theoretically, if all Netflix subscribers switch to this technology then Netflix can close its nation-wide distribution centers and also save on postage costs: assuming that Netflix pays the standard first-class mail rate of $0.42 to USPS, thats a $0.84 saving per mailed DVD. I think that the present overall cost of circulating a DVD to a user may be well above a dollar for Netflix.
- Centralized content control and the ability to speedily deploy new movies, shows etc.
- Ability to expand beyond the US in a relatively painless way - no distribution centers to set up, no additional staffing costs (analogous to how iTunes operates in Europe).
The Netflix system delivers video streams at 2.2 Mbps, 1Mbps, and an even lower bit-rate depending on the connection between the server and the receiving box. The quality naturally degrades according to the lessening bitrate, but let us assume that a user has a great Internet connection and that no bandwidth bottleneck exists between the serving CDN and this user and so s/he can watch the best 2.2Mbps quality for the entire 120 minutes of a movie.
Size of the movie:
2.2 Mbps x 7200 seconds (i.e. 120 minutes) = 15840 Mb = 15840/8 MB = 1980MB = 1980/1000 GB
= 1.98 GB.
So downloading a movie at the best quality means the CDN serves about 2GB of data to the end-user's Netflix- Roku box.
To arrive on the bandwidth costs, lets go with the figures presented in this PBS article about CDN pricing. Disclaimer: This article is more than a year old, and I have been reading about CDN price wars all along. So the current cost of bandwidth may actually be lower than stated.
From the PBS article the costs for streaming a 2GB stream to a user (assuming volume wholesale pricing):
Single server: $0.26
Akamai : $0.32
P2P: $0.0024
P2P: $0.0024
Ok first off, I like the P2P number the most but lets ignore that because P2P may not be able to compete in quality with CDNs (See my paper on this). Even if Netflix uses the most expensive Akamai CDN, they are getting away with just $32 cents per movie instead of the dollar-plus cost in the DVD-mailing model. Even if we assume a few more cents of overhead per movie due to the technology costs, I think Netflix is well in the green with this.
The beauty of Netflix's strategy is that they will be able to gradually wean people from the DVD mailing model to the this online content delivery model because of the convenience of the latter. And this without jeopardizing the DVD mailing model because there is no cannibalization here - its perfect migration with one less DVD mailing customer corresponding to one more streaming customer. Every DVD streamed will add up and lead to a drastic reduction in Netflix's operating costs.
Meanwhile, Roku will probably make some money out of their $99 box.
Last question: And the ISP?
Thats for later. Enjoy your movies.
Update: Netflix bandwidth costs come to about $5cents as of June 2009, according to this article.
Tuesday, May 20, 2008
If there is a Microsoft Yahoo deal then startups will feel the pinch
A Microsoft takeover of all or some of Yahoo will be a good thing for Microsoft in it's battle to unseat Google from the Internet's helm. Perhaps a later Microsoft-Facebook arrangement will finally present a credible challenge to Google. I doubt if the Yahoo board will now agree to anything less than the 72% premium over the original share price Microsoft had offered earlier, so Yahoo shareholders will also come out wealthier from the deal. End users are likely to benefit from a stronger alternative to Google as well.
But one quarter will suffer quietly in the short to medium term: startup companies. Yahoo and Microsoft are some of the most prolific startup acquirers (see Figure 1, from this blog). Yahoo merging with Microsoft removes a big buyer for many startup companies. Moreover, Microsoft will have that much less cash (approximately $44B less based on the first MS offer) to throw at startup acquisitions. With the credit supply tightening up and the economy slowing down, you can be sure of a capital drought ahead for many Internet and software startups.
Friday, May 16, 2008
Crude oil demand: India, China, and the USA
Figure 1: Crude oil imports of India, China, and the USACrude oil prices have never been higher (Brent sweet crude is trading at about $125 a barrel on the NYMEX as of this post). Part of the reason is attributed to the growing demand from emerging economies like India and China that is putting upward pressure on the price of oil. Alan Greenspan writes in his book that the annual world demand for for crude oil has grown by 1.6% since the late 80s while the production has only grown by 0.8% or so annually. The gap has lead investors to bid up crude oil futures in anticipation of the tightening supply, further driving up prices as the buffer between supply and demand has narrowed significantly.
I downloaded crude oil import data from the UN data website for India, China, and the USA and plotted it (Figure 1). Unsurprisingly, the USA imports far more crude oil than India or China. It is more interesting to note is that the growth in US crude oil imports has been of the same order or steeper than that of India and China. Therefore, demand is being driven higher more by the USA than by India or China.
In his book, Alan Greenspan speaks about the "crude oil intensity" of a nation, defined as its crude oil consumption normalized by its GDP. He states that this number is far higher for China and India than it is for the USA because the latter has shifted to a less oil-intensive service economy in the past few decades. From my perspective, I think that the real crude oil intensity of the USA may be much more than Greenspan computes it to be because of USA's large number of imports from China. For example, a plastic toy imported from China counts the crude oil used to manufacture it and transport it to the USA as crude oil used by China.
It seems clear that the biggest lever to reduce crude oil demand lies in the hands of the USA. India and China are emerging economies eager to lift 100s of millions of people out of poverty. As such, they may not have the political capital to cut back on their increasing (but still small) usage of crude oil. On the other hand, even a small percentage cutback in the USA will reduce demand significantly. Lets hope that the USA moves towards more efficient cars, better public transport systems and away from its suburban driving culture in order to keep crude oil within reach of poorer nations of the World.
I downloaded crude oil import data from the UN data website for India, China, and the USA and plotted it (Figure 1). Unsurprisingly, the USA imports far more crude oil than India or China. It is more interesting to note is that the growth in US crude oil imports has been of the same order or steeper than that of India and China. Therefore, demand is being driven higher more by the USA than by India or China.
In his book, Alan Greenspan speaks about the "crude oil intensity" of a nation, defined as its crude oil consumption normalized by its GDP. He states that this number is far higher for China and India than it is for the USA because the latter has shifted to a less oil-intensive service economy in the past few decades. From my perspective, I think that the real crude oil intensity of the USA may be much more than Greenspan computes it to be because of USA's large number of imports from China. For example, a plastic toy imported from China counts the crude oil used to manufacture it and transport it to the USA as crude oil used by China.
It seems clear that the biggest lever to reduce crude oil demand lies in the hands of the USA. India and China are emerging economies eager to lift 100s of millions of people out of poverty. As such, they may not have the political capital to cut back on their increasing (but still small) usage of crude oil. On the other hand, even a small percentage cutback in the USA will reduce demand significantly. Lets hope that the USA moves towards more efficient cars, better public transport systems and away from its suburban driving culture in order to keep crude oil within reach of poorer nations of the World.
Wednesday, May 14, 2008
On dear peer-to-peer
I will be presenting a paper* at the IEEE IwQoS early next month containing the analysis of a large scale peer-to-peer live video multicast streaming session on the Internet. Think of the P2P video multicast system as the Bittorrent for video streaming (instead of file-sharing). The system was sending a video stream of a baseball match to 10s of thousands of viewers on the Internet using P2P technology.
The presentation and paper are available online. Here are two results from the paper that in my opinion warrant particular notice.
Figure 1 shows the aggregate download and upload bandwidth consumed by the P2P system. Note the scale on the Y axis - Gbps! I am wondering, this is only 1 video stream. What happens to the Internet when 1000s of such streams become available online? Were networks designed for such usage?
An interesting artifact in this figure is that the aggregate download rate of all peers exceeds the aggregate upload rate of all peers. The difference was made up through "bandwidth injecting super-servers" of the content provider. Still, it is absolutely remarkable that the amount of additional bandwidth required is almost constant even as the number of peers increase (Figure 2).
*Joint work with Jatinder Pal Singh (T-Labs) and Aditya Mavlankar, Pierpaolo Baccichet, and Bernd Girod (Stanford University)
The presentation and paper are available online. Here are two results from the paper that in my opinion warrant particular notice.
Figure 1 shows the aggregate download and upload bandwidth consumed by the P2P system. Note the scale on the Y axis - Gbps! I am wondering, this is only 1 video stream. What happens to the Internet when 1000s of such streams become available online? Were networks designed for such usage?
An interesting artifact in this figure is that the aggregate download rate of all peers exceeds the aggregate upload rate of all peers. The difference was made up through "bandwidth injecting super-servers" of the content provider. Still, it is absolutely remarkable that the amount of additional bandwidth required is almost constant even as the number of peers increase (Figure 2).
Figure 1: Total bandwidth. Click to enlarge.
In Figure 2, you can see the number of concurrent peers in the P2P system over the time-period of the streamed game (hour 4 to hour 8). Look at the rate of change of peers in (peers joining, peers leaving) the P2P system. Keeping in mind that most of the bandwidth comes from these very peers, it is remarkable that this highly dynamic pool of peers is able to sustain the P2P system. Things get very exciting at the end of the baseball game (Hour 8): Everybody wants to leave. Now that is a big challenge for any P2P system. 
Figure 2: Peer Dynamics. Click to Enlarge.
*Joint work with Jatinder Pal Singh (T-Labs) and Aditya Mavlankar, Pierpaolo Baccichet, and Bernd Girod (Stanford University)
Saturday, May 10, 2008
Spinning a jetliner...in a loom!
There was an incredible article in Fortune about the manufacturing process of the Boeing 787. The first plane is slated to fly before the end of the year and Boeing is already reporting that the 787 is the fastest selling jetliner of all times. In fact, Boeing is taking flak from customers for delaying the delivery of the aircraft for want of parts. Apparently, a handful of suppliers just cannot keep up with the demand!
But what fascinated me was that the aircraft's shell will not be made out of aluminum alloys. Instead, it is made of carbon composites. This material is created from carbon fibers that are spun in a way reminiscent of spinning thread (See picture below). Epoxy raisins and subsequent heat treatment creates the carbon composite material for the plane's body. The material is lighter, stronger, and amenable to better aerodynamic design. For example, the entire toilet of the 787 weighs just 170 lb!
Spinning the carbon fibers for the Boeing 787 (courtesy, Fortune). The complete slide-show is available here.
Needless to say, the light aircraft means it is significantly more fuel efficient. At the same time, the greater strength means that the cabin can be pressurized to about 6000ft, making flying more comfortable. The material also allows more comfortable humidity levels in the cabin because unlike metals, carbon does not corrode.
Kudos to the Boeing engineers for designing this marvel!
But what fascinated me was that the aircraft's shell will not be made out of aluminum alloys. Instead, it is made of carbon composites. This material is created from carbon fibers that are spun in a way reminiscent of spinning thread (See picture below). Epoxy raisins and subsequent heat treatment creates the carbon composite material for the plane's body. The material is lighter, stronger, and amenable to better aerodynamic design. For example, the entire toilet of the 787 weighs just 170 lb!
Spinning the carbon fibers for the Boeing 787 (courtesy, Fortune). The complete slide-show is available here.Needless to say, the light aircraft means it is significantly more fuel efficient. At the same time, the greater strength means that the cabin can be pressurized to about 6000ft, making flying more comfortable. The material also allows more comfortable humidity levels in the cabin because unlike metals, carbon does not corrode.
Kudos to the Boeing engineers for designing this marvel!
Friday, May 9, 2008
The recession and US housing prices early in the decade
Figure 1:Median and Average Sales Prices of New Homes Sold in United States. Up, up, and then recently, down.Click to Enlarge
"In the United States, homes had increased in value so much that households, feeling flush, seemed more willing to spend"
It is widely acknowledged now (2008) that housing prices were inflated artificially due to the easy credit available in the first half of the decade. For example, Figure 1 shows the average and median US home prices between 1980 and 2007 (source: US census). Notice the very rapid increase in new home prices between 2000 and 2006. And the most recent slowdown.
Greenspan has touched on the fundamental force responsible for the 2001 recession being so mild - the economy's white knight in shining armor was the US consumer with pockets full from the soaring house prices. All those refinancing dollars kept up the consumer spending. The 2000-01 dot com debacle was perhaps larger than it seemed; but the cushioning effect of housing prices made the pain a lot less, back then.
Does this mean that it is payback time now? Did we end up borrowing from the future in 2001? With housing prices plateauing and actually decreasing in some markets, I very much doubt of housing will bail out the economy this time.
Wanted: New knight in shining armor, preferably resilient to speculative forces.
Well I've read that the weak dollar is good for US exports and also makes foreign imports dearer (e.g. $120+ oil). Perhaps these two factors will buttress the US economy this time. Wait and watch.
Thursday, May 8, 2008
Alan Greenspan's book
The Guru's book (click to visit Amazon site). Picture courtesy Penguin.
I have been reading Alan Greenspan's "The Age of Turbulence: Adventures in a New World" (ISBN 1594201315) over the past couple of days. This book is part autobiography, but given the stature of the man, the book gives an unique insight into how the Global economy has progressed since the War from the perspective of the most well known central banker of all times.
In the book, Alan declares his unflinching faith in Adam Smith's capitalist ideas. Interestingly he admits being deeply influenced by Ayn Rand's (sometimes extreme) beliefs in laissez-faire capitalism. Perhaps the fall of the Soviet system prior to his writing the book stoked the ferocity of Alan's pro-market capitalism beliefs in the book. Whatever the reasons, the fact that market capitalism remains the only time-tested successful economic system makes me comfortable with much of what he says on this topic.
But the book has a lot more to it. One of the interesting features is the interplay of monetary policy and politics in Washington described in the book. It is absolutely remarkable that Alan Greenspan successfully navigated a continuous 18-year term as Fed Chairman with presidents from either side of the political spectrum. Although Alan is a republican, he plainly states his poor opinion of George Bush and extols Bill Clinton"s economic policies. I believe that his ability to work with multiple administrations may also explain his ability to successfully tackle situations like the 87' stock market crash and the post 9/11 economic landscape.
The book explains the basic workings of the Fed in an easy-to-comprehend manner. You learn of technicalities like the Fed Fund rate and the Discount rate, the organizational structure of the Federal Reserve and its relation to the US Treasury, its mandate, etc. While this information is also available elsewhere, Alan brings facts to life by introducing the workings of the Fed through anecdotes and examples from his experience.
I am still on page 200. This is one of those rare books about which I hesitate to comment more before better understanding what the Guru wants us to hear. Stay tuned for more commentary on this superb book.
Saturday, April 19, 2008
TATA's acquisition spree. Answer to the "why" question
I have known Tata since I was a child. I rode Tata buses to school, soaped myself with Tata soaps, stayed in Tata hotels and probably lived in houses supported by Tata steel. More recently both my brother and my wife worked for a Tata company. But the Tata I knew then was different than today's Tata. The global, competitive, aggressive, and ambitious Tata.
India's Tata group has become very well known in Europe recently after taking over UK's Corus and Ford's Land Rover and Jaguar businesses. It is also in talks to buy T-Systems from Deutsche Telekom in Germany. If you add to all this the excitement of the €1800 Nano car designed by Tata, you have got a credible Asian multi-national company in the world's eyes.
Many question the business sense of taking over Landrover and Jaguar given that the premium attached to these brands has a minuscule market in India, where a Hyundai Sonata is considered a luxury salon car! Others question the ability of the Tatas to control unionized European operations.
But I am bullish about their recent acquisitions and their ability to turn these into strategic wins. The foremost reason for my belief is the relative professionalism in the way Tatas conduct their business. For example, top Tata managers of the holding company, Tata Sons, are selected and groomed through the Tata Administrative Service (TAS), admission to which is based on a merit-based, competitive and through screening process. So we can be certain that folks running the acquisition show from the Tata side will be competent and highly trained.
The second reason for my bullish assessment is the value of the technology transfer from Jaguar and Landrover to Tata. About 8 years ago Tata motors rode a huge success in the "Tata SUMO", a rugged diesel-powered 4x4 that looked like a SUV but cost a lot less. The SUMO was an instant hit because it rode well on India's broken roads and because the government of India subsidizes diesel, it was highly cost effective. I still remember seeing caravans of hired SUMOs on highways during weekends and vacations.
Then Toyota came and stole the show with the Toyota "Qualis". This gem had more to offer: Toyota quality, quieter engine, superior interiors, and better fuel efficiency. Although the Qualis was priced slightly higher than the SUMO, it quickly overtook the latter. Tata had lost out because Toyota had superior technology. Lesson learn t for Tata: India had stepped out of its socialist past and now quality and technology mattered to Indian customers.
Jaguar and Landrover will fill this important gap for Tata. Another example where Tata can benefit from better technology is Tata's subcompact "Indica". I have ridden this car and can confidently state that it is noisier and bumpier than its Suzuki counterpart on Indian roads. Jaguar and Landrover technology will perfectly compliment Tata technology. A company that produces some of the cheapest steel in the world (because Tata owns iron and coal mines in India) combined with an established brand and distribution network in India will be unbeatable with the infusion of the latest technical know how from the acquisitions.
India's Tata group has become very well known in Europe recently after taking over UK's Corus and Ford's Land Rover and Jaguar businesses. It is also in talks to buy T-Systems from Deutsche Telekom in Germany. If you add to all this the excitement of the €1800 Nano car designed by Tata, you have got a credible Asian multi-national company in the world's eyes.
Many question the business sense of taking over Landrover and Jaguar given that the premium attached to these brands has a minuscule market in India, where a Hyundai Sonata is considered a luxury salon car! Others question the ability of the Tatas to control unionized European operations.
But I am bullish about their recent acquisitions and their ability to turn these into strategic wins. The foremost reason for my belief is the relative professionalism in the way Tatas conduct their business. For example, top Tata managers of the holding company, Tata Sons, are selected and groomed through the Tata Administrative Service (TAS), admission to which is based on a merit-based, competitive and through screening process. So we can be certain that folks running the acquisition show from the Tata side will be competent and highly trained.
The second reason for my bullish assessment is the value of the technology transfer from Jaguar and Landrover to Tata. About 8 years ago Tata motors rode a huge success in the "Tata SUMO", a rugged diesel-powered 4x4 that looked like a SUV but cost a lot less. The SUMO was an instant hit because it rode well on India's broken roads and because the government of India subsidizes diesel, it was highly cost effective. I still remember seeing caravans of hired SUMOs on highways during weekends and vacations.
Then Toyota came and stole the show with the Toyota "Qualis". This gem had more to offer: Toyota quality, quieter engine, superior interiors, and better fuel efficiency. Although the Qualis was priced slightly higher than the SUMO, it quickly overtook the latter. Tata had lost out because Toyota had superior technology. Lesson learn t for Tata: India had stepped out of its socialist past and now quality and technology mattered to Indian customers.
Jaguar and Landrover will fill this important gap for Tata. Another example where Tata can benefit from better technology is Tata's subcompact "Indica". I have ridden this car and can confidently state that it is noisier and bumpier than its Suzuki counterpart on Indian roads. Jaguar and Landrover technology will perfectly compliment Tata technology. A company that produces some of the cheapest steel in the world (because Tata owns iron and coal mines in India) combined with an established brand and distribution network in India will be unbeatable with the infusion of the latest technical know how from the acquisitions.
Sunday, April 6, 2008
Beyond desktop search...can we make user-PC data more valuable?
I ordered an 8GB flash disk last week (turns out there is a 16GB one around, but I am modest ;-) ). Since I don't have a whole lot of media content to put on this fat-stick, I will instead end up putting all my work over the past few years on it. If I factor in the emails, I should easily fill up 8GB with a couple of years' worth of data. Wow. I remember having a hard time filling a DSDD 5.25 inch 576 kB diskette back in the early 90s.
The low down is that we have *lots* of data. 7MP pictures, podcasts, email archives, documents and web-downloads, not to mention audio/visual media - all this can quickly add up. Fortunately storage has kept up, or perhaps the pace of storage encourages more data generation in the first place? Whatever the truth, we have a situation where we have a whole lot of data sitting in our computers.
There have been many instances of large volumes of data in non-PC computer scenarios. For example, real databases have routinely run into terabytes. The key difference between user-PC data and these databases is the heterogeneity and the lack of structure in the former. User-PC data comes in various formats and is generated by completely different applications. Even when the same application generates the data (e.g. an email mailbox file) the goal has never been to store the data in a way extract global information later.
Desktop search software is the first step in mining information from User-PC data. But search is really a very preliminary tool because it only flags the existence of the information sought via the specified key-words. There is very little cognizance of the bigger picture. Data mining - that power tool which works so beautifully for databases and other highly structured data - does not exist yet for User-PC data.
Isn't it time we started building algorithms beyond just search to help users extract useful information from their gigabytes of data?
The low down is that we have *lots* of data. 7MP pictures, podcasts, email archives, documents and web-downloads, not to mention audio/visual media - all this can quickly add up. Fortunately storage has kept up, or perhaps the pace of storage encourages more data generation in the first place? Whatever the truth, we have a situation where we have a whole lot of data sitting in our computers.
There have been many instances of large volumes of data in non-PC computer scenarios. For example, real databases have routinely run into terabytes. The key difference between user-PC data and these databases is the heterogeneity and the lack of structure in the former. User-PC data comes in various formats and is generated by completely different applications. Even when the same application generates the data (e.g. an email mailbox file) the goal has never been to store the data in a way extract global information later.
Desktop search software is the first step in mining information from User-PC data. But search is really a very preliminary tool because it only flags the existence of the information sought via the specified key-words. There is very little cognizance of the bigger picture. Data mining - that power tool which works so beautifully for databases and other highly structured data - does not exist yet for User-PC data.
Isn't it time we started building algorithms beyond just search to help users extract useful information from their gigabytes of data?
Friday, March 28, 2008
ASUS EEPC horror story
Last week I was at the Tridentcom conference in Innsbruck. There, while attending a talk, I saw first-hand the horror of a presentation gone completely wrong, the discomfort of the audience, and the pain of an embarrassed speaker as his ASUS EEPC failed miserably. The presenters beautiful slides were cut horizontally (about 30% of the lower part of each slide was missing) because the ASUS EEPC could not drive the overhead projector properly. Every other laptop, including old clunky student-budget ones, running Windows , Linux, and Mac OS, were successful in beaming presentations. But not the ASUS EEPC.
There are many objective reviews of laptops on the Internet based on specifications, design, speed, etc. They try to compare products side by side so that potential buyers can choose the product that is best for them. Still, somethings are considered standard and not even mentioned - like the assurance that the power adaptor will charge the laptop's battery, the battery won't burst, the USB ports will work, and the VGA output will work. Seasoned customers are smart enough to get a mix of online and off-line opinions about a product before buying it. But sometimes when products are just released, it is hard to ascertain whether a product will serve its purpose down the road. I hope this EEPC horror story gives folks some additional information before they buy it.
Its all nice to tout the small, cheap ASUS EEPC. But seriously, didn't VGA-out technology mature like 15 years ago? And ASUS cannot even get this right in 2008? My 2 cents - get a second or third hand Pentium 3 laptop or something instead.
There are many objective reviews of laptops on the Internet based on specifications, design, speed, etc. They try to compare products side by side so that potential buyers can choose the product that is best for them. Still, somethings are considered standard and not even mentioned - like the assurance that the power adaptor will charge the laptop's battery, the battery won't burst, the USB ports will work, and the VGA output will work. Seasoned customers are smart enough to get a mix of online and off-line opinions about a product before buying it. But sometimes when products are just released, it is hard to ascertain whether a product will serve its purpose down the road. I hope this EEPC horror story gives folks some additional information before they buy it.
Its all nice to tout the small, cheap ASUS EEPC. But seriously, didn't VGA-out technology mature like 15 years ago? And ASUS cannot even get this right in 2008? My 2 cents - get a second or third hand Pentium 3 laptop or something instead.
Monday, March 24, 2008
Recursion and "Towers of Hanoi"
Figure 1: rules of the Hanoi puzzle. Click to enlarge
I was thinking of my first algorithms class and remembered the "Towers of Hanoi" problem. This problem is used to introduce the concept of recursion. It can also use the stack data structure (LIFO) quite naturally, making it a universal favorite in assignments. An Internet search yields 1000's of websites discussing the problem. Heres adding yet another discussion to this timeless classic!
Problem Setup
Here is the setup and the rules of the Hanoi puzzle
- There are 3 towers labeled 0,1, and 2.
- There are N circular discs, each of different radius, that are initially placed around tower 0.
- Any circular disc can only be placed above a disc of larger radius, or as the first disc of the tower.
Figure 1 explains the problem graphically and shows the rules of the Hanoi puzzle.
Solution
In order to solve the puzzle recursively, look at Figure 2. The first requirement on moving the largest (red) disc from tower 0 (source tower) to tower 2 (destination tower) is that there should be no discs over this red disc. This means that the other 2 discs (green and yellow) should be moved to tower 1 (auxiliary tower) and the setup should be in state 1. Then, the red disc can be moved to tower 2 (state 2).
Now the problem is reduced to one with just 2 discs (yellow and green). These need to be moved from tower 1 (the source) to tower 3 (the destination) using tower 0 as a temporary go-between (auxiliary tower).
Figure 2: Top level steps. Click to enlarge
But wait, how do we accomplish the transition from state 0 to state 1?
Figure 3 shows the intermediate steps to accomplish this. The aim is to move the green and yellow discs from tower 0 (source) to tower 1 (destination) using tower 2 as the auxiliary tower.
Figure 3: Mini-steps from state 0 to state 1. Click to Enlarge#include <stack>
#include <vector>
#include <iostream>
using namespace std;
//Each Tower is a Stack (LIFO)
vector <stack <int>*> towers; //Vector of pointers to stacks
//Printing the tower contents. This is only for eye-candy.
void PrintTowers()
{
stack <int> tempStack;
for (int ii=0;ii<towers.size();ii++) {
cout << std::endl<< "Tower " << ii <<": ";
while (!towers[ii]->empty()) {
tempStack.push(towers[ii]->top());
towers[ii]->pop();
}
while (!tempStack.empty()) {
towers[ii]->push(tempStack.top());
cout <<tempStack.top()<<" ";
tempStack.pop();
}
cout << " <-- TOP";
}
}
//Move from Tower "from" to Tower "to"
void MoveDisc(int from, int to)
{
towers[to]->push(towers[from]->top());
towers[from]->pop();
}
//Recursive function Hanoi - the most interesting function
//When this function exits, it has moved the lowest
//Tower (as specified by numDiscs) from the sourceTower to the
//destTower using the auxTower as a temporary holder
void Hanoi(int sourceTower, int destTower, int auxTower, int numDiscs)
{
if (numDiscs==0)
return;
Hanoi(sourceTower, auxTower, destTower, numDiscs-1);
MoveDisc(sourceTower,destTower);
Hanoi(auxTower,destTower,sourceTower,numDiscs-1);
}
int main()
{
int numDiscs;
cout << "Please enter the number of discs: ";
cin >> numDiscs;
//Initialize the Towers by allocating 3 stacks
for (int ii=0;ii < 3;ii++)
towers.push_back(new stack<int>);
//Initial condition: all the discs are on Tower 0
for (int jj=numDiscs-1;jj >=0 ;jj--)
towers[0]->push(jj);
//Print setup of towers
cout <<std::endl<<"Initially";
PrintTowers();
//Enter recursive function here
Hanoi(0, 2, 1, numDiscs);
//Print setup of towers
cout <<std::endl<<"Finally";
PrintTowers();
//Don't forget to delete the vector of stacks.
for (int ii=0;ii < 3; ii++)
delete towers[ii];
cout << std::endl << "Done.";
return 0;
}
Saturday, March 22, 2008
Our world needs electricity, lots of it.
(Click to enlarge)
I visited the UN data website and downloaded data about the total electricity production of countries and matched it with their populations in order to obtain the electricity produced per 1000 inhabitants (for each country). I have plotted a histogram of this in the figure above.
This histogram is disturbing.
The smaller issue is that inhabitants of most countries have lesser electricity than the world average. This means that a few energy-rich countries are producing (and probably consuming) most of the world's electricity. I have marked some of the representative countries on the histogram. There is a table at the end of this post containing the parsed data in case you want to look up your own country and/or use the data (After citing the UN data source, off course).
The bigger issue is that countries with low electricity per capita (bars toward the left of the figure) are striving to move the per capita electricity production higher to improve quality of life. For example, both India and China are lower than the world average. And I have the impression that these countries are really looking to improve their citizen's living conditions. And remember, populations are increasing too (see one of my previous posts), making it necessary to pump up electricity production even faster.
Producing more electricity is a positive development. But the problems associated with increasing production are the issue here. Here are some questions:
- Where are we going to get the energy to increase electricity production so rapidly?
- What will be the environmental cost of creating so much additional capacity? I hope it is renewable energy. Hope. Hope. Hope.
- Or, does this analysis indicate that even in the next decades electricity will be a premium, for-the-well-off, limited quantity luxury given the lack of such a massive energy source?
Tough cookies.
We really need a breakthrough with some new technology here.
Here is the table containing data used in the analysis.
Country, million kWh per 1000 inhabitants (German notation: "," is the decimal point)
| Afghanistan | 0,019507403 |
| Albania | 0,529214445 |
| Algeria | 0,219150336 |
| American Samoa | 0,936753525 |
| Angola | 0,032618392 |
| Anguilla | 1,036227154 |
| Antigua and Barbuda | 0,325148424 |
| Argentina | 0,727408376 |
| Armenia | 1,07765584 |
| Aruba | 1,457768448 |
| Australia | 2,492244294 |
| Austria | 2,280999506 |
| Azerbaijan | 0,617455344 |
| Bahamas | 1,40738335 |
| Bahrain | 2,551090802 |
| Bangladesh | 0,027811644 |
| Barbados | 0,739895798 |
| Belarus | 0,819169464 |
| Belgium | 1,54779036 |
| Belize | 0,174199589 |
| Benin | 0,006949106 |
| Bermuda | 2,726961075 |
| Bhutan | 0,549439336 |
| Bolivia | 0,149749265 |
| Bosnia and Herzegovina | 0,69957433 |
| Botswana | 0,118195712 |
| Brazil | 0,49861704 |
| British Virgin Islands | 0,454215116 |
| Brunei Darussalam | 2,030329213 |
| Bulgaria | 1,545853099 |
| Burkina Faso | 0,005598074 |
| Burundi | 0,004199119 |
| Cambodia | 0,013614697 |
| Cameroon | 0,049170704 |
| Canada | 3,765512578 |
| Cape Verde | 0,157851016 |
| Cayman Islands | 2,346954443 |
| Central African Republic | 0,010259031 |
| Chad | 0,002858379 |
| Chile | 0,798215316 |
| China | 0,386906459 |
| Colombia | 0,296546128 |
| Comoros | 0,006266434 |
| Congo | 0,025762836 |
| Cook Islands | 0,57208238 |
| Costa Rica | 0,44965969 |
| Croatia | 0,849392177 |
| Cuba | 0,379683488 |
| Cyprus | 1,34517727 |
| Czech Republic | 1,708438639 |
| Democratic People's Republic of Korea | 0,402276274 |
| Democratic Republic of the Congo | 0,043802793 |
| Denmark | 2,471503772 |
| Djibouti | 0,146728575 |
| Dominica | 0,353841391 |
| Dominican Republic | 0,582812306 |
| Ecuador | 0,273103278 |
| Egypt | 0,280151791 |
| El Salvador | 0,184723191 |
| Equatorial Guinea | 0,026854067 |
| Eritrea | 0,036892038 |
| Estonia | 1,702729723 |
| Faeroe Islands | 1,804792034 |
| Falkland Islands (Malvinas) | 3,025210084 |
| Fiji | 0,199264292 |
| Finland | 3,139151247 |
| French Guiana | 0,728790884 |
| French Polynesia | 0,442041685 |
| Gabon | 0,325406584 |
| Gambia | 0,018552543 |
| Georgia | 0,977777798 |
| Germany | 1,51273341 |
| Ghana | 0,065320583 |
| Gibraltar | 1,202749141 |
| Greece | 1,20759618 |
| Greenland | 1,844280122 |
| Grenada | 0,304075563 |
| Guadeloupe | 0,937493585 |
| Guam | 3,274604022 |
| Guatemala | 0,162208554 |
| Guinea | 0,022771058 |
| Guinea-Bissau | 0,01315024 |
| Guyana | 0,415837246 |
| Haiti | 0,023772922 |
| Honduras | 0,212566084 |
| Hungary | 0,856203515 |
| Iceland | 5,200654647 |
| India | 0,126738013 |
| Indonesia | 0,116874477 |
| Iran (Islamic Republic of) | 0,639435492 |
| Iraq | 0,300043035 |
| Ireland | 1,518598487 |
| Israel | 1,541832479 |
| Jamaica | 0,425354403 |
| Japan | 2,168335174 |
| Jordan | 0,389966498 |
| Kazakhstan | 1,231640364 |
| Kenya | 0,034242581 |
| Kiribati | 0,032607632 |
| Kuwait | 4,02037037 |
| Kyrgyzstan | 0,710476911 |
| Lao People's Democratic Republic | 0,08121598 |
| Latvia | 0,940571111 |
| Lebanon | 0,601385281 |
| Liberia | 0,054622645 |
| Libyan Arab Jamahiriya | 0,865970274 |
| Lithuania | 1,330189073 |
| Luxembourg | 3,631083653 |
| Madagascar | 0,012230063 |
| Malawi | 0,01376068 |
| Malaysia | 0,829451232 |
| Maldives | 0,165934635 |
| Mali | 0,0098182 |
| Malta | 2,28753381 |
| Marshall Islands | 0,303244006 |
| Martinique | 1,000262695 |
| Mauritania | 0,058047217 |
| Mauritius | 0,554314346 |
| Mexico | 0,490100396 |
| Mongolia | 0,322392649 |
| Montserrat | 1,776830135 |
| Morocco | 0,172225006 |
| Mozambique | 0,115377076 |
| Myanmar | 0,024954518 |
| Namibia | 0,034659007 |
| Nauru | 0,989021857 |
| Nepal | 0,022551405 |
| Netherlands | 1,3307455 |
| Netherlands Antilles | 1,126657796 |
| New Caledonia | 1,528705938 |
| New Zealand | 2,168356638 |
| Nicaragua | 0,099770455 |
| Niger | 0,007916051 |
| Nigeria | 0,041604152 |
| Niue | 0,612745098 |
| Oman | 1,189848435 |
| Pakistan | 0,123101766 |
| Palau | 2,583594177 |
| Panama | 0,508432302 |
| Papua New Guinea | 0,117468448 |
| Paraguay | 1,25604174 |
| Peru | 0,228699463 |
| Philippines | 0,185003073 |
| Poland | 0,844522287 |
| Portugal | 1,269159686 |
| Puerto Rico | 1,370991383 |
| Qatar | 3,553189833 |
| Republic of Korea | 1,389956686 |
| Romania | 0,876196974 |
| Russian Federation | 1,619416414 |
| Rwanda | 0,004223616 |
| Saint Helena | 0,625097672 |
| Saint Kitts and Nevis | 0,407016973 |
| Saint Lucia | 0,40932771 |
| Saint Pierre and Miquelon | 4,254648598 |
| Saint Vincent and the Grenadines | 0,29377943 |
| Samoa | 0,157741576 |
| Sao Tome and Principe | 0,032760677 |
| Saudi Arabia | 1,420230761 |
| Senegal | 0,048341849 |
| Seychelles | 1,110695412 |
| Sierra Leone | 0,008771297 |
| Singapore | 2,347562131 |
| Slovakia | 1,624096551 |
| Slovenia | 1,496430224 |
| Solomon Islands | 0,02963471 |
| South Africa | 0,835171394 |
| Spain | 1,888334973 |
| Sri Lanka | 0,126093294 |
| Sudan | 0,030204543 |
| Suriname | 0,859729307 |
| Swaziland | 0,122718045 |
| Sweden | 3,694381387 |
| Syrian Arab Republic | 0,398277093 |
| Tajikistan | 0,678298553 |
| Thailand | 0,52931205 |
| The former Yugoslav Republic of Macedonia | 0,767583489 |
| Timor-Leste | 0,042163059 |
| Togo | 0,007694068 |
| Tonga | 0,080514488 |
| Trinidad and Tobago | 1,118059532 |
| Tunisia | 0,326482221 |
| Turkey | 0,532316671 |
| Turkmenistan | 0,811252681 |
| Turks and Caicos Islands | 0,163538984 |
| Uganda | 0,010743706 |
| Ukraine | 1,119794335 |
| United Arab Emirates | 3,827701301 |
| United Kingdom | 1,358755508 |
| United Republic of Tanzania | 0,01426794 |
| United States of America | 3,558514712 |
| Uruguay | 0,629035396 |
| Uzbekistan | 0,440301803 |
| Vanuatu | 0,055719101 |
| Viet Nam | 0,140517355 |
| Western Sahara | 0,131690083 |
| Zambia | 0,196892977 |
| Zimbabwe | 0,178739129 |
Wednesday, March 19, 2008
GENI and Networking Research: Inside out, or outside in?
The Global Environment for Network Innovations (GENI) idea is to build an experimental facility that researchers can use to experiment with new communications and networking technology, distributed systems, cyber-security aspects, and applications. A couple of weeks ago I attended a talk given by Craig Patridge, chief scientist at BBN technologies. Craig is heading the GENI project office tasked with implementing GENI. He is an engaging speaker and got me thinking about the merits of building GENI.
GENI is a sort of first for the National Science Foundation (NSF) and the network research community. NSF occasionally funds large infrastructure projects like building astronomy telescopes and particle accelerators but this is the first time that a networking infrastructure is being funded. The interesting thing is that the infrastructure comes first and then protocols or services follow. Moreover, the infrastructure will be built based on requirements specified by the research community. Is this the future of network research?
The current Internet is an engineering marvel. It scaling property is absolutely remarkable - 100s of millions of hosts in a federated environment with completely different underlying access technologies just work. Then the creative engineers and innovators come in to shape the Internet APIs (e.g. IP communication stack) into myriad applications - email, VOIP, P2P, Web 2.0, digital libraries, and whatever else they can think of.
The Internet was first built by engineers, and later scientists highlighted several flaws in its design. This has sometimes served as a good feedback loop for refining the Internet over time. For example, security researchers have continually unearthed security holes in the IP socket stack. Scientists, coming from the outside, study the insides of the Internet and contribute to refining the already-built Internet.
But can researchers with limited engineering experience design a new communication infrastructure such as the GENI infrastructure? I very much doubt this. Researchers are seldom successful in building viable commercial technologies. They are very smart but usually focused on one or few problems. It is not at all clear if GENI could deliver the next Internet.
But lets back-pedal a little. Is GENI supposed to be building the next Internet? Answer: perhaps not. But what I find troubling about the GENI (or FIRE - the European counterpart) is that there is that almost the whole OSI stack - network, transport, session and applications - is supposed to come from the research community. I really really wonder who is going to write all this up? Off course there can be a module-based approach to plugging in pre-existing pieces into GENI, but then how is this Internet design revolutionary, and does this justify building GENI in the first place? Why not stick with something more real like PlanetLab?
I don't believe scientists can build another Internet from the inside out. Shouldn't building a new network, from the inside, be left to the engineers?
GENI is a sort of first for the National Science Foundation (NSF) and the network research community. NSF occasionally funds large infrastructure projects like building astronomy telescopes and particle accelerators but this is the first time that a networking infrastructure is being funded. The interesting thing is that the infrastructure comes first and then protocols or services follow. Moreover, the infrastructure will be built based on requirements specified by the research community. Is this the future of network research?
The current Internet is an engineering marvel. It scaling property is absolutely remarkable - 100s of millions of hosts in a federated environment with completely different underlying access technologies just work. Then the creative engineers and innovators come in to shape the Internet APIs (e.g. IP communication stack) into myriad applications - email, VOIP, P2P, Web 2.0, digital libraries, and whatever else they can think of.
The Internet was first built by engineers, and later scientists highlighted several flaws in its design. This has sometimes served as a good feedback loop for refining the Internet over time. For example, security researchers have continually unearthed security holes in the IP socket stack. Scientists, coming from the outside, study the insides of the Internet and contribute to refining the already-built Internet.
But can researchers with limited engineering experience design a new communication infrastructure such as the GENI infrastructure? I very much doubt this. Researchers are seldom successful in building viable commercial technologies. They are very smart but usually focused on one or few problems. It is not at all clear if GENI could deliver the next Internet.
But lets back-pedal a little. Is GENI supposed to be building the next Internet? Answer: perhaps not. But what I find troubling about the GENI (or FIRE - the European counterpart) is that there is that almost the whole OSI stack - network, transport, session and applications - is supposed to come from the research community. I really really wonder who is going to write all this up? Off course there can be a module-based approach to plugging in pre-existing pieces into GENI, but then how is this Internet design revolutionary, and does this justify building GENI in the first place? Why not stick with something more real like PlanetLab?
I don't believe scientists can build another Internet from the inside out. Shouldn't building a new network, from the inside, be left to the engineers?
Sunday, March 16, 2008
Bullish about mobile/cellular networks
We all know that cellular mobile networks are rapidly expanding all over the world - in fact the rate of adoption of cellular mobile technology has been faster than that of the Internet. I am bullish about this technology's role in human development. The bar-graph says it all. Amen!
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