2008-10-30
Post Pushed Back to Saturday
I have a final tomorrow morning so I'm pushing back my regularly scheduled post to Saturday. Until then you can rest easy knowing that the Dutch word for glove is "Handschoen".
2008-10-29
Taxes Across Countries
The Organization for Economic Co-operation & Development (OECD) has released their annual report of taxes across countries. This year's data comes from 2006. Quick hits of average tax rates:
Mexico - 21%
US - 28%
Switzerland - 30%
Netherlands - 39%
Denmark - 49%
The brief is mostly European countries, ostensibly due to information availability.
I'm not looking forward to taxes next year, though supposedly I can apply to be tax-free in Holland the first three years I'm here.
Mexico - 21%
US - 28%
Switzerland - 30%
Netherlands - 39%
Denmark - 49%
The brief is mostly European countries, ostensibly due to information availability.
I'm not looking forward to taxes next year, though supposedly I can apply to be tax-free in Holland the first three years I'm here.
2008-10-27
(Roughly) Half of a Plane Ticket's Cost is Fuel
(there is an edit at the bottom of this post)
Due to some commentary on my last post, I decided to calculate how much you pay for fuel when you fly.
While kilos lifted and moved might be a small fraction of the total cost, it is still a fraction of the total cost. But what fraction?
Wikipedia says that *new* aircraft consume about 3 L / 100 km for only the passenger, not the luggage. Thus, per passenger, we're looking at 30 cc per km. Let's assume an average weight of 72 kg per passenger. Now we've got .42 cc / (km * kg). Gas prices are tough, because they're over $6 in Europe but only $2.50 in the states (airplane fuel costs nearly the same amount as car fuel, I don't have a great source on this). We'll assume gas is $3.78 a gallon, or 1$ for 10^-3 cc. So fuel is .42 cc / (km * kg) * 1 $ / (10^3 cc), so the conversion between dollars and km * kg is:
4.2 * 10^-4 dollars / (km * kg).
NYC is about 6,000 km from Amsterdam. 20 kg * 6,000 km * 4.2 * 10^-4 $ / (km * kg) comes to (drum roll):
50$ (EDIT: This is overstated by a factor of 10 - see below)
I looked at ticket prices for a flight from NYC to Amsterdam in February. With tax, a round trip ticket is about $800. For 80 kg of load, that is $200 each way, or $400. Fuel is about *half* the price of your ticket. This meshes with what was presented in our 6.UAT lecture on estimation...wow, that class actually came in handy for something.
One further assumption is required for the above to be valid: burned fuel must scale linearly with weight. We'll leave that one to the reader.
If fuel is indeed half the cost of a plane ticket, why does a 60 kg person with 5 kg of luggage pay the same $800 as an 80 kg person with 20 kg of luggage? The 65 kg of weight should pay less than $700.
And why does going to a XXX2 matinee cost the same amount as going to see The Dark Knight?
EDIT: loyal reader asc has pointed out that the fuel efficiency should include the plane's weight. If we look at the weight of an A380, we see the plane is about 275,000 kg when empty. 555 passengers at 90 kg apiece (72 kg weight plus 18 kg luggage) weigh 50,000 kg. Including other weight (seats, fuel, etc.), it seems reasonable that the passengers account for at least 10% of the total weight. If we assume 50% of ticket price is fuel, we're looking at more than 5% of a ticket's price being fuel to move you and your stuff. Thus we're down to the Hamilton range:
Though this is hazy economics range, I maintain airlines could still turn a profit here. We know that $15 changes in ticket price have large effects on consumer behavior. Smaller customers would be more likely to fly an airline that charged by gross weight, meaning a charge-per-weight airline would be taking the smaller customers from its competitors, and leaving them with the larger (more expensive) ones. Furthermore, I haven't even mentioned non-financial incentives. Wouldn't you be happy flying an airline that charged people based on the amount of fuel they burn?
Due to some commentary on my last post, I decided to calculate how much you pay for fuel when you fly.
While kilos lifted and moved might be a small fraction of the total cost, it is still a fraction of the total cost. But what fraction?
Wikipedia says that *new* aircraft consume about 3 L / 100 km for only the passenger, not the luggage. Thus, per passenger, we're looking at 30 cc per km. Let's assume an average weight of 72 kg per passenger. Now we've got .42 cc / (km * kg). Gas prices are tough, because they're over $6 in Europe but only $2.50 in the states (airplane fuel costs nearly the same amount as car fuel, I don't have a great source on this). We'll assume gas is $3.78 a gallon, or 1$ for 10^-3 cc. So fuel is .42 cc / (km * kg) * 1 $ / (10^3 cc), so the conversion between dollars and km * kg is:
4.2 * 10^-4 dollars / (km * kg).
NYC is about 6,000 km from Amsterdam. 20 kg * 6,000 km * 4.2 * 10^-4 $ / (km * kg) comes to (drum roll):
50$ (EDIT: This is overstated by a factor of 10 - see below)
I looked at ticket prices for a flight from NYC to Amsterdam in February. With tax, a round trip ticket is about $800. For 80 kg of load, that is $200 each way, or $400. Fuel is about *half* the price of your ticket. This meshes with what was presented in our 6.UAT lecture on estimation...wow, that class actually came in handy for something.
One further assumption is required for the above to be valid: burned fuel must scale linearly with weight. We'll leave that one to the reader.
If fuel is indeed half the cost of a plane ticket, why does a 60 kg person with 5 kg of luggage pay the same $800 as an 80 kg person with 20 kg of luggage? The 65 kg of weight should pay less than $700.
And why does going to a XXX2 matinee cost the same amount as going to see The Dark Knight?
EDIT: loyal reader asc has pointed out that the fuel efficiency should include the plane's weight. If we look at the weight of an A380, we see the plane is about 275,000 kg when empty. 555 passengers at 90 kg apiece (72 kg weight plus 18 kg luggage) weigh 50,000 kg. Including other weight (seats, fuel, etc.), it seems reasonable that the passengers account for at least 10% of the total weight. If we assume 50% of ticket price is fuel, we're looking at more than 5% of a ticket's price being fuel to move you and your stuff. Thus we're down to the Hamilton range:
Though this is hazy economics range, I maintain airlines could still turn a profit here. We know that $15 changes in ticket price have large effects on consumer behavior. Smaller customers would be more likely to fly an airline that charged by gross weight, meaning a charge-per-weight airline would be taking the smaller customers from its competitors, and leaving them with the larger (more expensive) ones. Furthermore, I haven't even mentioned non-financial incentives. Wouldn't you be happy flying an airline that charged people based on the amount of fuel they burn?
Airlines and Movie Theaters
A few days ago Continental Airlines announced it would be shrinking its luggage allowance. While perusing this article, I thought of pricing at movie theaters.
Movie theaters price matinee tickets uniformly - if you go to a movie on a Friday night, you'll shell out $10 whether you're seeing The Dark Knight or XXX2. I'd consider seeing XXX2 if it cost less than The Dark Knight.
For airlines, you pay the same amount no matter your weight. I can think of a few girls that pay the same for a plane ticket as I do, even though they are at least 20 kilograms lighter than I am (with luggage, though, we probably cost the same to fly).
Why do you think movie theaters and airlines have flat pricing? A "pay per kilo" model would probably insult airline's overweight customers, though $15 must make a big difference when we're booking plane fare. I'm waiting for the "pay per kilo" airline. You'd buy a ticket with a weight allowance, and pay extra if you and your luggage (together) are over this weight.
Movie theaters price matinee tickets uniformly - if you go to a movie on a Friday night, you'll shell out $10 whether you're seeing The Dark Knight or XXX2. I'd consider seeing XXX2 if it cost less than The Dark Knight.
For airlines, you pay the same amount no matter your weight. I can think of a few girls that pay the same for a plane ticket as I do, even though they are at least 20 kilograms lighter than I am (with luggage, though, we probably cost the same to fly).
Why do you think movie theaters and airlines have flat pricing? A "pay per kilo" model would probably insult airline's overweight customers, though $15 must make a big difference when we're booking plane fare. I'm waiting for the "pay per kilo" airline. You'd buy a ticket with a weight allowance, and pay extra if you and your luggage (together) are over this weight.
Daylight Savings Time
Clocks moved an hour back today for everyone in the Netherlands. In the states this happens next week. WTF?
2008-10-25
Border Issues
If you think the U.S. has border issues, imagine what the Netherlands and Belgium have to go through in Baarle-Nassau (google maps link).
In other news, southern towns in the Netherlands are having trouble with the tourist influx caused by the cannabis shops. The Dutch have a very tolerant view of drugs, but no tolerance for violence. An excerpt from Cop in the Hood:
In other news, southern towns in the Netherlands are having trouble with the tourist influx caused by the cannabis shops. The Dutch have a very tolerant view of drugs, but no tolerance for violence. An excerpt from Cop in the Hood:
I saw a police officer give an addict back his heroin when the addict was released after a night in jail for some petty crime. I expressed my amazement to the officer that he could give illegal drugs back to a criminal. He explained to me that as soon as the man ran out of heroin, he would break into a car to get money to buy his next hit. It made no sense to the police officer to hasten the addict’s next criminal act by taking away his drugs. I asked about sending the wrong message. The police officer said his message was stop breaking into cars.
2008-10-24
More Bicycles
This is going to be a photo-centered post about bicycles. I'd read about Holland and Denmark having a lot of bicycles, but I had not seen images that convinced me this was the case. I'm going to show some infrastructure and pictures to convince you about the pervasiveness of bicycles in Holland. But first I'm going to go over a standard Dutch bicycle.
I bought a bicycle last weekend:
My bicycle is a standard Dutch bicycle. There are a few things you'll notice are different than an American bicycle. First of all, there is the luggage rack over the rear tire. All standard bicycles in Holland have these racks. When I say standard, I mean bicycles which aren't racing or folding bicycles. Second, the handlebars are curved. Very few bicycles have straight handlebars. I'd guess it is a style thing, though I'm saying this simply because I understand neither style nor curved handlebars so I'm lumping the two together. The lock is also a bit different, as the next three photos show. The first photo is a picture of the left side - there is a key that cannot be removed unless you turn the metal bar on the right side. The bar goes into the back wheel. You can see the bar in second and third photos below.
Next to my bicycle this morning was another type of Dutch bicycle:
While buying my bike, I asked the store clerk about why some bikes have the curved metal like this one. He said it is a girl's model (I swear I've seen guys riding bikes like these). He didn't have a good reason was it is a girl's model, but it does look more stylish than a standard bicycle.
As I wrote in my post on my apartment, the building has bicycle sheds. Here is a photo of one floor's bicycle shed:
There is also a general area for parking bicycles in the apartment building:
My workplace actually has an underground bicycle parking lot! Rijwielingang, the sign over the entrace, literally means "row wheel entrance". Rijwiel, or "row wheel", is one of the three common Dutch words for a bicycle - the other two are fiets and tweewieler. "Ingang" means entrance. Google Translate only bats about .750 with Dutch.
To give you an idea of how common bicycle commuting is, here are some other "parking lots". The first picture was taken outside my building at about 5 pm. Parking underground is a bit of a hassle, as you have to pedal up the tunnel - a lot of people park outside and risk the rain. The second shot was taken at the library (bibliotheek). The third shot shows one of five or six parking lots near the train station.
Finally, to give you an idea of the infrastructure I've been talking about, I took a picture of the bicycle "light" at an intersection. You can see that bicycles, like cars, have to wait at a stoplight when crossing an intersection. There is a push button for requesting a crossing. The bicycle request button has a feedback light, but the pedestrian button does not.
As for roads, you can see above that bicycles have separate roads from the cars. Most bicycle paths are next to the street, as you can see in the first two photos below. There are lots of bicycle-only paths, like the third photo.
The next photo is a bit difficult to describe. Due to the train traffic, few streets cross the train tracks, most go under or over. There is a big tunnel that goes under the train tracks near the town center. There are two separate tunnels for bicyclists and moped riders on the outside, and two tunnels of two lanes for cars and motorcyclists in the middle of the bridge. The sign with a red circle on the border of a car and a motorcycle signifies that cars and motorcycles are not to use the outside path.
If you are wondering about scooters, my experience is that scooters are considered a type of moped. I believe there are six classes of traffic on the road: trucks, cars, motorcycles, scooters/mopeds, bicycle, and pedestrians. I've seen a motorcycle or two take a path valid for scooters/mopeds, but I'm pretty sure this is illegal.
While I was "driving" home from work yesterday, Abtswoudsebrug had to let a boat through. The bridge is only for pedestrians and bicyclists, and it was a bit of a traffic jam.
The second photo above shows a common type of bag placed across the luggage rack of a bicycle.
If you want to see more about the types of bicycles, I suggest this post. The author has a lot of pictures of types of bicycles, and talks about the things that surprise foreigners (buitenlanders). First, helmets are the exception, rather than the rule. Policemen and children wear helmets, but no one else. Second, formally dressed individuals ride bicycles, even women in skirts. A girl will sometimes wear a skirt over tight black pants, I'm assuming the pants protect against the cold and make riding a bicycle less awkward. Third, it is common for a second person to ride on the luggage rack. Guys will "ride luggage" (I made that up) with other guys, too, though this is less common.
The only type of bicycle the other post missed mentioning is the folding bicycle. I didn't get a good shot of one, as these bicycles are less common. You see a folded bicycle every now and then on the train. One can bring a non-folding bicycle onto roughly half of the trains, though this requires a special ticket. Folding bicycles are allowed onto all the trains at no extra charge.
I hope you enjoyed the set of photos discussing bicycles in Delft. I'll post updates if I ever find a folding bicycle.
I bought a bicycle last weekend:
My bicycle is a standard Dutch bicycle. There are a few things you'll notice are different than an American bicycle. First of all, there is the luggage rack over the rear tire. All standard bicycles in Holland have these racks. When I say standard, I mean bicycles which aren't racing or folding bicycles. Second, the handlebars are curved. Very few bicycles have straight handlebars. I'd guess it is a style thing, though I'm saying this simply because I understand neither style nor curved handlebars so I'm lumping the two together. The lock is also a bit different, as the next three photos show. The first photo is a picture of the left side - there is a key that cannot be removed unless you turn the metal bar on the right side. The bar goes into the back wheel. You can see the bar in second and third photos below.
Next to my bicycle this morning was another type of Dutch bicycle:
While buying my bike, I asked the store clerk about why some bikes have the curved metal like this one. He said it is a girl's model (I swear I've seen guys riding bikes like these). He didn't have a good reason was it is a girl's model, but it does look more stylish than a standard bicycle.
As I wrote in my post on my apartment, the building has bicycle sheds. Here is a photo of one floor's bicycle shed:
There is also a general area for parking bicycles in the apartment building:
My workplace actually has an underground bicycle parking lot! Rijwielingang, the sign over the entrace, literally means "row wheel entrance". Rijwiel, or "row wheel", is one of the three common Dutch words for a bicycle - the other two are fiets and tweewieler. "Ingang" means entrance. Google Translate only bats about .750 with Dutch.
To give you an idea of how common bicycle commuting is, here are some other "parking lots". The first picture was taken outside my building at about 5 pm. Parking underground is a bit of a hassle, as you have to pedal up the tunnel - a lot of people park outside and risk the rain. The second shot was taken at the library (bibliotheek). The third shot shows one of five or six parking lots near the train station.
Finally, to give you an idea of the infrastructure I've been talking about, I took a picture of the bicycle "light" at an intersection. You can see that bicycles, like cars, have to wait at a stoplight when crossing an intersection. There is a push button for requesting a crossing. The bicycle request button has a feedback light, but the pedestrian button does not.
As for roads, you can see above that bicycles have separate roads from the cars. Most bicycle paths are next to the street, as you can see in the first two photos below. There are lots of bicycle-only paths, like the third photo.
The next photo is a bit difficult to describe. Due to the train traffic, few streets cross the train tracks, most go under or over. There is a big tunnel that goes under the train tracks near the town center. There are two separate tunnels for bicyclists and moped riders on the outside, and two tunnels of two lanes for cars and motorcyclists in the middle of the bridge. The sign with a red circle on the border of a car and a motorcycle signifies that cars and motorcycles are not to use the outside path.
If you are wondering about scooters, my experience is that scooters are considered a type of moped. I believe there are six classes of traffic on the road: trucks, cars, motorcycles, scooters/mopeds, bicycle, and pedestrians. I've seen a motorcycle or two take a path valid for scooters/mopeds, but I'm pretty sure this is illegal.
While I was "driving" home from work yesterday, Abtswoudsebrug had to let a boat through. The bridge is only for pedestrians and bicyclists, and it was a bit of a traffic jam.
The second photo above shows a common type of bag placed across the luggage rack of a bicycle.
If you want to see more about the types of bicycles, I suggest this post. The author has a lot of pictures of types of bicycles, and talks about the things that surprise foreigners (buitenlanders). First, helmets are the exception, rather than the rule. Policemen and children wear helmets, but no one else. Second, formally dressed individuals ride bicycles, even women in skirts. A girl will sometimes wear a skirt over tight black pants, I'm assuming the pants protect against the cold and make riding a bicycle less awkward. Third, it is common for a second person to ride on the luggage rack. Guys will "ride luggage" (I made that up) with other guys, too, though this is less common.
The only type of bicycle the other post missed mentioning is the folding bicycle. I didn't get a good shot of one, as these bicycles are less common. You see a folded bicycle every now and then on the train. One can bring a non-folding bicycle onto roughly half of the trains, though this requires a special ticket. Folding bicycles are allowed onto all the trains at no extra charge.
I hope you enjoyed the set of photos discussing bicycles in Delft. I'll post updates if I ever find a folding bicycle.
2008-10-22
When Will They Learn?
You don't put MIT in an online poll. Or even better, you don't run online polls with tech schools as choices.
The latest victim is here. Looks like Drexel and Texas Tech beat the MIT script kiddies to the punch, though - it'll be interesting to see who wins first. Either way, the web-site is running really, *really* slow. Poor call, Victoria's Secret.
The latest victim is here. Looks like Drexel and Texas Tech beat the MIT script kiddies to the punch, though - it'll be interesting to see who wins first. Either way, the web-site is running really, *really* slow. Poor call, Victoria's Secret.
Just One of Those Days
Today is going to be one of Those Days.
I think I'm going to get a wiki with graphviz up and running. It won't be the most productive thing to do, but documenting is always useful.
I think I'm going to get a wiki with graphviz up and running. It won't be the most productive thing to do, but documenting is always useful.
2008-10-20
Mapic
While browsing the BBC's How Will You Die? map, I came up with the bright idea to start a web-comic based on maps. I do like the maps.
Wacko Political Views
I know this is all over the 'net, but I have deep respect for Colin Powell and his stance on the Republican party's current insinuations:
During this interview, Powell also mentioned one of the most poignant photographs I've seen. The photo is from a high-quality, New Yorker slideshow.
(props to the New Yorker for being a classy magazine)
I'm also troubled by, not what Sen. McCain says, but what members of the party say, and it is permitted to be said such things as: "Well, you know that Mr. Obama is a Muslim." Well, the correct answer is: he is not a Muslim. He's a Christian. He's always been a Christian.
But the really right answer is: What if he is? Is there something wrong with being a Muslim in this country? The answer is: No, that's not America. Is there something wrong with some 7-year-old, Muslim-American kid believing he or she can be President?
Yet I have heard senior members of my own party drop the suggestion: he's a Muslim, and he might be associated with terrorists. This is not the way we should be doing it in America.
During this interview, Powell also mentioned one of the most poignant photographs I've seen. The photo is from a high-quality, New Yorker slideshow.
(props to the New Yorker for being a classy magazine)
2008-10-17
Job: Kindergarten Teacher
During my first two weeks in Zuid-Holland, I didn't have regular internet and wrote a lot of posts on my laptop. I have now run out of posts. I've been a bit busy with VHDL the past few days (yesterday I checked roughly 15,000 lines of VHDL into our repository! 14,900 of these lines were code-generated test vectors, however, so I'm not really that productive). Anyways, I don't really have a great post ready, so I'm going to give a high level overview of VHSIC hardware description language (VHDL), a language I've had to use at work recently. This post is geared towards non-technical readers - most of my university friends have taken a processor architecture class which requires the use of a custom hardware description language similar to VHDL.
Nearly all software languages are serial, meaning they completely execute one instruction before starting on the next. Statements have a linear structure, such as:
get out of bed
eat breakfast
clean dishes
check RSS reader for Oog Robot posts
take shower
brush teeth
The correct output of the program relies on the statements being executed *in order*. A reason that computer programs were originally built like this is that sharing is hard. Even in the example above, someone wouldn't want to take a shower while another person was washing dishes. Well, at least in my apartment there would be little reason to sing in the shower.
In contrast is a completely parallel model of execution. In a parallel model, everything occurs at the same time. A simple analogy is a woodworking assembly line and a carpenter. Serial programs are like carpenters - only a few things can occur at a time. I say a few because a good carpenter might cut one piece of wood while she waits for the varnish to dry on another. At the end of the day, however, there is a limit to how many things one carpenter can do.
Parallel programs are like assembly lines, as work can scale with size. While assembly lines can do a lot more work, they are not as easy to set up. The amount of coordination must also scale with the number of workers. The output and input of subsequent stages must match in attributes like volume and timing, or else mishaps such as pile-ups start to occur.
For a concrete example, say we want to make a peanut butter and jelly sandwich. Here are the steps at a certain level of detail:
Take out plate
Take out bread
Take out PB
Take out J
Take out PB knife
Take out J knife
Spread PB on bread with PB knife
Spread J on bread with J knife
Put away bread
Put away PB
Put away J
Put away PB knife
Put away J knife
Put bread together
In a serial program we have to make sure all the instructions are in the right order, and place these instructions in order. In a parallel program, however, we can leverage the fact that some things can occur at the same time. We could have a "bread factory", a "PB spreading factory", a "J spreading factory", and a "sandwich from pre-spread bread factory".
Bread factory:
Take out bread
Give out bread on request
Put away bread
PB spreading factory:
Take out PB
Take out PB knife
Get bread from "bread factory"
Spread PB on bread
Pass bread w/ PB downstream
Put away PB
Put away knife
J spreading factory:
Take out J
Take out J knife
Get bread from "bread factory"
Spread J on bread
Pass bread w/ J downstream
Put away J
Put away knife
Sandwich factory:
Take out plate
Take PB-bread from PB factory
Take J-bread from J factory
Put slices of bread together
Thus the factories can work at the same time. The sandwich factory and J-bread factory can be taking out plates and J, respectively. Note that while we have more instructions overall due to coordination (and I've even skipped some coordination instructions), each of the specific units is much simpler than the entire program. Understanding a complex system requires breaking down functionality into smaller chunks. Serial programs also aggregate functionality for understandability in a similar way.
As computers evolve it will be interesting to watch the two types of programs evolve. The speed of computer processors has not increased much over the past few years. Processor manufacturers have started to put multiple sets of older, single processors (called cores) into their fancy new processors. Small modifications to serial programs can easily take advantage of a few of these cores, but major modifications or complex procedures are required for serial programs to take advantage of a lot of cores (more than, say, 16).
Anyways, I work with field-programmable gate arrays (FPGAs), which require parallel programs. I'm writing software and coordination routines which allow a light sensor (like your eye) to talk to a display. One can implement serial programs, but one must write a parallel program with complex signaling to do this (or take a freely available one). Thus a good statement of my job is that right now I'm coordinating interactions between a bunch of components. Except the components are like my red-headed stepchildren, and they really don't want to talk to one another. Especially that ones that aren't supposed to be talking to one another.
Nearly all software languages are serial, meaning they completely execute one instruction before starting on the next. Statements have a linear structure, such as:
get out of bed
eat breakfast
clean dishes
check RSS reader for Oog Robot posts
take shower
brush teeth
The correct output of the program relies on the statements being executed *in order*. A reason that computer programs were originally built like this is that sharing is hard. Even in the example above, someone wouldn't want to take a shower while another person was washing dishes. Well, at least in my apartment there would be little reason to sing in the shower.
In contrast is a completely parallel model of execution. In a parallel model, everything occurs at the same time. A simple analogy is a woodworking assembly line and a carpenter. Serial programs are like carpenters - only a few things can occur at a time. I say a few because a good carpenter might cut one piece of wood while she waits for the varnish to dry on another. At the end of the day, however, there is a limit to how many things one carpenter can do.
Parallel programs are like assembly lines, as work can scale with size. While assembly lines can do a lot more work, they are not as easy to set up. The amount of coordination must also scale with the number of workers. The output and input of subsequent stages must match in attributes like volume and timing, or else mishaps such as pile-ups start to occur.
For a concrete example, say we want to make a peanut butter and jelly sandwich. Here are the steps at a certain level of detail:
Take out plate
Take out bread
Take out PB
Take out J
Take out PB knife
Take out J knife
Spread PB on bread with PB knife
Spread J on bread with J knife
Put away bread
Put away PB
Put away J
Put away PB knife
Put away J knife
Put bread together
In a serial program we have to make sure all the instructions are in the right order, and place these instructions in order. In a parallel program, however, we can leverage the fact that some things can occur at the same time. We could have a "bread factory", a "PB spreading factory", a "J spreading factory", and a "sandwich from pre-spread bread factory".
Bread factory:
Take out bread
Give out bread on request
Put away bread
PB spreading factory:
Take out PB
Take out PB knife
Get bread from "bread factory"
Spread PB on bread
Pass bread w/ PB downstream
Put away PB
Put away knife
J spreading factory:
Take out J
Take out J knife
Get bread from "bread factory"
Spread J on bread
Pass bread w/ J downstream
Put away J
Put away knife
Sandwich factory:
Take out plate
Take PB-bread from PB factory
Take J-bread from J factory
Put slices of bread together
Thus the factories can work at the same time. The sandwich factory and J-bread factory can be taking out plates and J, respectively. Note that while we have more instructions overall due to coordination (and I've even skipped some coordination instructions), each of the specific units is much simpler than the entire program. Understanding a complex system requires breaking down functionality into smaller chunks. Serial programs also aggregate functionality for understandability in a similar way.
As computers evolve it will be interesting to watch the two types of programs evolve. The speed of computer processors has not increased much over the past few years. Processor manufacturers have started to put multiple sets of older, single processors (called cores) into their fancy new processors. Small modifications to serial programs can easily take advantage of a few of these cores, but major modifications or complex procedures are required for serial programs to take advantage of a lot of cores (more than, say, 16).
Anyways, I work with field-programmable gate arrays (FPGAs), which require parallel programs. I'm writing software and coordination routines which allow a light sensor (like your eye) to talk to a display. One can implement serial programs, but one must write a parallel program with complex signaling to do this (or take a freely available one). Thus a good statement of my job is that right now I'm coordinating interactions between a bunch of components. Except the components are like my red-headed stepchildren, and they really don't want to talk to one another. Especially that ones that aren't supposed to be talking to one another.
2008-10-16
Cartoon Off
I don't like to post about links I see from reddit.com, but the cartoon-off between XKCD and the New Yorker is the classiest thing to happen this year.
2008-10-14
I'm Horrible at First Person Shooters...
...but unfortunately my experience with other computer games implies I have quick reflexes. Supposedly quick reflexes are not good in a lover.
Hmmmm, would I rather have poor reflexes or be a good lover? Tough call.
Hmmmm, would I rather have poor reflexes or be a good lover? Tough call.
Small-town Iowa in the News
It is pretty rare when I come across an article about a small town in Iowa, but within the last day I've seen three. Probably just coincidence.
A Class Divided - with the increasing focus on race in the current presidential campaign, PBS hopes to teach people with the anecdotal evidence of a 1970 discrimination experiment in Riceville, IA.
Immigration Problems - Still angry at the recent raids on a meat packer in Postville, IA, politicians blame the gov't for the increase in crime and drop in business. Meanwhile in the US, there still is no immigration path for unskilled workers.
The Oxford Project - 20 years later, a new book focuses on the residents of Oxford, IA. Probably just a PR article.
A Class Divided - with the increasing focus on race in the current presidential campaign, PBS hopes to teach people with the anecdotal evidence of a 1970 discrimination experiment in Riceville, IA.
Immigration Problems - Still angry at the recent raids on a meat packer in Postville, IA, politicians blame the gov't for the increase in crime and drop in business. Meanwhile in the US, there still is no immigration path for unskilled workers.
The Oxford Project - 20 years later, a new book focuses on the residents of Oxford, IA. Probably just a PR article.
2008-10-11
Exposure Troubles
I couldn't get the levels quite right. Even in the original, high-res version the middle clouds look a little blocky, and the trees below the cloud line are too dark.
2008-10-10
Vacation in Iceland?
With Iceland's financial collapse, your dollars (or euros) will buy a lot more in the small country. Assuming you can find food to buy.
A Trip to the Bank
Despite what google tells you, "to pull" in Dutch is "trekken". Trekken also means "draw", in both the "draw on" and "horse-drawn carriage" sense of the word draw. "To push" is "buwen".
Dutch fire code does not require doors to open outward like American fire code requires, meaning you shouldn't assume that a door opens outwards when outside a building. These sorts of assumptions will screw you when you're attempting to enter the bank. There will be a bunch of giggling teenage girls are behind you, and you'll never forget that "buwen" means push. And they said degrees from MIT would help open doors. Lies.
I wonder why the Dutch don't take fire code so seriously. Doors in America always open outwards so no one gets trapped behind the door. And there aren't embarrassing moments like these. Well, at least not outside of buildings.
Anyways, on to the main point of this post, a short discussion about differences in banking. In order to open a bank account at ABN-AMRO, a bank in the Netherlands, one must schedule an appointment several days to a week in advance. I don't know if it is ABN-AMRO specifically, but an email I received from HR implies that all banks are this way. I've opened three checking accounts in America with three different banks, and every time I just walked in and 15 minutes later I walked out with a checking account.
Two weeks after said embarrassing encounter and several days after my appointment, I received my debit card in the mail. Instead of a 16 digit credit card number, my account number is on the debit card! Putting a different, 16-digit number onto a debit card serves two purposes to my knowledge. The first reason is that a debit card can have the same interface as a credit card - sellers don't need two different mechanisms for payment. It would be a big hassle to parse two sets of information, go to a different interface based on the info, etc. The second reason is that your debit card doesn't contain your account number, so your account number is not suspect if you lose your debit card. Every American check contains one's account number, however, so I suppose it isn't so bad if the account number is compromised.
The debit card also has a formatted version of my name, an expiration date, and a "card number" which contains roughly the same amount of information as the CVV number of the back of my American credit cards (short aside: did you know that Canadians hate it when US citizens call themselves American? They're North American, and hence American, too). The card is called a "Wereldpas", meaning (you guessed it) "world pass". The card also contains a ChipKnip contact.
ChipKnip, from my limited understanding, is a standardized interface to vending machines and small payment devices. You have to go to a special ATM-like machine to take money from your main account and place this money onto/into the ChipKnip portion of your card. At my appointment the teller described ChipKnip as a coin-purse on your debit card, but quickly moved on, probably not wishing to stretch her English nor explain such a "basic" concept. I'm very interested in the security of the device. How do you prevent people from taking advantage of ChipKnip? Expect a post sometime in the future as I learn more about how the ChipKnip device works.
Roughly a day after the mailman delivered my debit card, I received an authentication device for internet banking, and a letter thanking me for asking not to receive paper statements. I'll be writing more about the security of this device in a later post.
For all the trouble I went through to setup a bank account, there won't be much money in it until next month. I need a SoFi number (social fiscal, Dutch equivalent of SSN) before the Universiteit can pay me. Until then I'll be eating pasta.
(This post was written on my laptop, before I had regular internet access. No animals were harmed, though some red tape did suffer damage.)
Dutch fire code does not require doors to open outward like American fire code requires, meaning you shouldn't assume that a door opens outwards when outside a building. These sorts of assumptions will screw you when you're attempting to enter the bank. There will be a bunch of giggling teenage girls are behind you, and you'll never forget that "buwen" means push. And they said degrees from MIT would help open doors. Lies.
I wonder why the Dutch don't take fire code so seriously. Doors in America always open outwards so no one gets trapped behind the door. And there aren't embarrassing moments like these. Well, at least not outside of buildings.
Anyways, on to the main point of this post, a short discussion about differences in banking. In order to open a bank account at ABN-AMRO, a bank in the Netherlands, one must schedule an appointment several days to a week in advance. I don't know if it is ABN-AMRO specifically, but an email I received from HR implies that all banks are this way. I've opened three checking accounts in America with three different banks, and every time I just walked in and 15 minutes later I walked out with a checking account.
Two weeks after said embarrassing encounter and several days after my appointment, I received my debit card in the mail. Instead of a 16 digit credit card number, my account number is on the debit card! Putting a different, 16-digit number onto a debit card serves two purposes to my knowledge. The first reason is that a debit card can have the same interface as a credit card - sellers don't need two different mechanisms for payment. It would be a big hassle to parse two sets of information, go to a different interface based on the info, etc. The second reason is that your debit card doesn't contain your account number, so your account number is not suspect if you lose your debit card. Every American check contains one's account number, however, so I suppose it isn't so bad if the account number is compromised.
The debit card also has a formatted version of my name, an expiration date, and a "card number" which contains roughly the same amount of information as the CVV number of the back of my American credit cards (short aside: did you know that Canadians hate it when US citizens call themselves American? They're North American, and hence American, too). The card is called a "Wereldpas", meaning (you guessed it) "world pass". The card also contains a ChipKnip contact.
ChipKnip, from my limited understanding, is a standardized interface to vending machines and small payment devices. You have to go to a special ATM-like machine to take money from your main account and place this money onto/into the ChipKnip portion of your card. At my appointment the teller described ChipKnip as a coin-purse on your debit card, but quickly moved on, probably not wishing to stretch her English nor explain such a "basic" concept. I'm very interested in the security of the device. How do you prevent people from taking advantage of ChipKnip? Expect a post sometime in the future as I learn more about how the ChipKnip device works.
Roughly a day after the mailman delivered my debit card, I received an authentication device for internet banking, and a letter thanking me for asking not to receive paper statements. I'll be writing more about the security of this device in a later post.
For all the trouble I went through to setup a bank account, there won't be much money in it until next month. I need a SoFi number (social fiscal, Dutch equivalent of SSN) before the Universiteit can pay me. Until then I'll be eating pasta.
(This post was written on my laptop, before I had regular internet access. No animals were harmed, though some red tape did suffer damage.)
2008-10-08
2008-10-06
SPADs mentioned at Ars Technica
Ars Technica mentioned single photon avalanche detectors (SPADs) in an article on quantum crypto today. I'm working with these avalanche detectors - I'll be giving an overview on SPADs pretty soon on my blog. Stay tuned!
Inches overseas
Computer/laptop monitor sizes in Europe are *not* reported in centimeters, as one expects, but in inches. A 19" monitor is a 19" where ever you go. I don't think I've run across anything else in inches.
TV screen sizes are reported in cm, though.
2008-10-03
I Knew It!
When speed dating, women are nearly as shallow as men.
Strong evidence that women base a first impression on the same characteristics as men.
Strong evidence that women base a first impression on the same characteristics as men.
Apartment
This post contains a description of reserving my apartment, and a breakdown of my apartment. Note that when I talk about floors (1st floor, 2nd floor, etc.), I mean European floors, which are 0-indexed.
Reserving my apartment was simple. An HR rep forwarded me a DUWO (short stay housing company) form which needed to be filled out at least three months in advance. Seriously, everything takes three months in Holland. After completing and returning the form, I received a confirmation letter via email. I showed up at the housing agency, paid my deposit and rent (they take cash), and received my keys. There is an indoor bike shed I can use when I buy my bicycle. The floor hallways are outside.
Security is physical key based. Everyone has a mailbox key. The second key is used to open the ground-level doors, your bike shed's door, your floor's door, and your room's door. There is also an emergency exit. While your key only opens your particular floor's door, the emergency exit doors aren't locked. I made the 13 floor journey to get photos from the 17th floor.
My apartment is a pretty standard studio apartment. The apartment came furnished...well, European furnished, as the coffee mug is a bit small. The heating is pretty bad, temperature stays at 20 Celsius (68 Fahrenheit) during the day, at night it drops to 15 Celsius (59 Fahrenheit). According to the rental agreement my room can be searched at any point in time. I am not allowed to:
- have guests stay overnight (doubles aren't allowed to have more than two people stay overnight)
- add appliances (microwave, rice cooker are used as examples, no rigorous definition of appliance is given)
- drives nails anywhere
- paint
I wonder if you can get kicked out of the country for breaking your rental agreement?
The apartment consists of three rooms and an entrance. The entrance is pretty non-chalant, so I'll go over the rooms from worst to best.
The bathroom is horrible, and the German shelf-toilet will give me nightmares for years to come. With an American toilet, one's business goes into water, but no water covering means that the bathroom smells compared to an American one. There are other shortcomings, but there is something called "Too Much Information". Google information about German toilets if you are interested.
The shower gives out hot water, but the water pressure is awful (I played around with the values, but don't think I can adjust this from my apartment). There is no good de-humidifying method, so the mirror stays fogged up after a shower. The shower lip keeps the water near the shower, but the floor is curved away from the shower lip and the toilet sits in a depression - accidently spraying water over the shower lip means a pool forms near the toilet. This is easily the worst bathroom I've had. Possibly even worse than the shallow Goodale bathroom when it turned sketchy my sophomore year.
The bathroom is so awful I hope no one wants to come and visit me until I find a better apartment. (Everyone I've told still has a standing invitation, but I'll sweat bullets worrying about my bathroom)
The kitchen is a mixed bag. I don't have a microwave nor oven, and since I'm a rule-follower to the letter there will never be one in my apartment. The kitchen came with hot plates and a pot, so I'm pretty set on pasta. The fridge is okay, there isn't a freezer (no ice cream!) but it is bigger than a standard cube fridge.
The main room is huge. Seriously, I could host a party in here (not going to happen). There are two massive West facing windows, both keep my apartment hot at the end of a sunny day. The windows are semi-opaque from one meter off the ground to two meters off the ground so people walking by can only see your floor and ceiling. The bed is a bit too springy. This surprised me, as Dutch people are tall (average adult male height is 6') and taller people usually sleep on firm mattresses. Otherwise one's spine gets tangled up and you wake up with a sore lower back.
My room number is actually my street address. Rooms are odd-numbered from 3 to 749 over 17 floors. Roughly 400 people live in my building (more on Dutch apartment buildings later). The first number of a room doesn't correspond to the floor, my room is in the 100s but I live on the fourth floor. There are five washers and three dryers. For 400 people, 5 washers! The laundry machines are small, too: 1 American load == 1.5 European loads. Laundry is expensive at 2 euros per wash or dry, and will run about 6 euros (10 dollars) a week for me. The laundry machines suffer concurrency issues like nobody's business on the weekends. Poor engineering, not enough redundancy.
All and all, I'm pretty happy with my place. Large windows can compensate for a lot. Watching the sun set, I remind myself how important it is to take it all in. One day the sun will be gone (preferably at my hand), and it will no longer set in the west. Muahaha.
Reserving my apartment was simple. An HR rep forwarded me a DUWO (short stay housing company) form which needed to be filled out at least three months in advance. Seriously, everything takes three months in Holland. After completing and returning the form, I received a confirmation letter via email. I showed up at the housing agency, paid my deposit and rent (they take cash), and received my keys. There is an indoor bike shed I can use when I buy my bicycle. The floor hallways are outside.
Security is physical key based. Everyone has a mailbox key. The second key is used to open the ground-level doors, your bike shed's door, your floor's door, and your room's door. There is also an emergency exit. While your key only opens your particular floor's door, the emergency exit doors aren't locked. I made the 13 floor journey to get photos from the 17th floor.
My apartment is a pretty standard studio apartment. The apartment came furnished...well, European furnished, as the coffee mug is a bit small. The heating is pretty bad, temperature stays at 20 Celsius (68 Fahrenheit) during the day, at night it drops to 15 Celsius (59 Fahrenheit). According to the rental agreement my room can be searched at any point in time. I am not allowed to:
- have guests stay overnight (doubles aren't allowed to have more than two people stay overnight)
- add appliances (microwave, rice cooker are used as examples, no rigorous definition of appliance is given)
- drives nails anywhere
- paint
I wonder if you can get kicked out of the country for breaking your rental agreement?
The apartment consists of three rooms and an entrance. The entrance is pretty non-chalant, so I'll go over the rooms from worst to best.
The bathroom is horrible, and the German shelf-toilet will give me nightmares for years to come. With an American toilet, one's business goes into water, but no water covering means that the bathroom smells compared to an American one. There are other shortcomings, but there is something called "Too Much Information". Google information about German toilets if you are interested.
The shower gives out hot water, but the water pressure is awful (I played around with the values, but don't think I can adjust this from my apartment). There is no good de-humidifying method, so the mirror stays fogged up after a shower. The shower lip keeps the water near the shower, but the floor is curved away from the shower lip and the toilet sits in a depression - accidently spraying water over the shower lip means a pool forms near the toilet. This is easily the worst bathroom I've had. Possibly even worse than the shallow Goodale bathroom when it turned sketchy my sophomore year.
The bathroom is so awful I hope no one wants to come and visit me until I find a better apartment. (Everyone I've told still has a standing invitation, but I'll sweat bullets worrying about my bathroom)
The kitchen is a mixed bag. I don't have a microwave nor oven, and since I'm a rule-follower to the letter there will never be one in my apartment. The kitchen came with hot plates and a pot, so I'm pretty set on pasta. The fridge is okay, there isn't a freezer (no ice cream!) but it is bigger than a standard cube fridge.
The main room is huge. Seriously, I could host a party in here (not going to happen). There are two massive West facing windows, both keep my apartment hot at the end of a sunny day. The windows are semi-opaque from one meter off the ground to two meters off the ground so people walking by can only see your floor and ceiling. The bed is a bit too springy. This surprised me, as Dutch people are tall (average adult male height is 6') and taller people usually sleep on firm mattresses. Otherwise one's spine gets tangled up and you wake up with a sore lower back.
My room number is actually my street address. Rooms are odd-numbered from 3 to 749 over 17 floors. Roughly 400 people live in my building (more on Dutch apartment buildings later). The first number of a room doesn't correspond to the floor, my room is in the 100s but I live on the fourth floor. There are five washers and three dryers. For 400 people, 5 washers! The laundry machines are small, too: 1 American load == 1.5 European loads. Laundry is expensive at 2 euros per wash or dry, and will run about 6 euros (10 dollars) a week for me. The laundry machines suffer concurrency issues like nobody's business on the weekends. Poor engineering, not enough redundancy.
All and all, I'm pretty happy with my place. Large windows can compensate for a lot. Watching the sun set, I remind myself how important it is to take it all in. One day the sun will be gone (preferably at my hand), and it will no longer set in the west. Muahaha.
2008-10-01
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