Next

Next

Next is one of the most useful ideas that mathematics ever invented.  We often start a list without thinking about how large it might become. Often we will implicitly make a choice,  three digits mean no more than 1000 members, 4 digits mean 10,000.  The nine digit social security number runs out of space at only 1,000,000,000
people, and with a population of 350,000,000 we are starting to get close.

If you are naming things using sequence numbers, next is simple. Just add 1 to the last number you used.  If you are at 5392 then the next one is 5393.  Simple.  You never run out. They are all different.

But what if you want more information.  Suppose that the number is stamped on the object you are numbering.  When you see the object at some future time, you want to know when it was numbered without looking it up in your records.  Well, if you want to more information in the number, it will have to be longer.  for example,  2014-07-23-5393.  5393 was numbered on July 23, 2014.
So our simple sequence number has expanded by 8 digits, and you can now tell when it was made.  The dashes make it easier to read, 201407235393 is hard to read.  And next year 2015110127281 will
be harder to read.  (2015-11-01-27281)

How can we make this numbering system better?  Let us look at several options with two things in mind.  1:  It should be easy for the user to understand the numbers.  2:  Fewer characters is better.

If we leave the dashes out, the string of numbers becomes shorter, easier to write, BUT harder to understand.  In this case, the punctuation wins.  The dashes are important to understanding.   what about the year?  Will you be numbering these things in the year 3247?  Well, you will not, but will someone be doing it? What about 2147, will someone be doing this in a hundred years?   So can we drop the first two characters?
         2014-07-23-5393 => 14-07-23-5393 ?

A casual user seeing this for the first time might identify 2014 as a year.  And from that, decode the whole sequence number.  Is that a good thing.  Do you want just anybody to identify the date?  That takes the whole matter up a level.  A question for management.

Similarly, the month identifier, 07.  If we use O for October, N for November and D for December, we can drop the zero. 1 for January,  6 for June, 7 for July.  Two characters become one character.  We add two characters to the character set.
           2014-07-23-5393 => 14-7-23-5393.

For the day, we could do a similar thing, but adding 22 characters
would be very confusing.  Hard to use.

The 5393 is next.  If you know the final number, 5393, you can look up all the other information. It uniquely identifies the object it is assigned to.  Suppose that instead of using 5393 we use the number since the day started, and further suppose that we never have as many as 100 new things in a day.  so if 5393 is the sixth thing numbered on July 23, 2014 we can assign 14-7-23-06 to the object.

So we have assigned an unique identifier to objects that arise somehow no more than 99 on one day between 1/1/2000 and 12/31/2099.  And the date the identifier was assigned is easy to read.  And 7 characters are used.

Unfortunately,  a normal sorting program will put 15-D-07-22 before 15-N-07-22; November comes before December.  Bummer!

Tilapia

Tilapia is the genus of a bunch of fish from Africa.
In the US,  Lepomis is the genus that has the same ecological niche.  Lepomis is the genus of the bluegill and all the many similar fishes
in North America.  Tilapia has one feature that seems strange in America.  All of the Tilapia species can use air to breathe.  None of the American fishes can use air directly,  but most of the fishes in central Africa can use air to support their life.  Why??

Much of Africa is a high altitude.  I taught at the Haile Sellasie College of Agriculture so many years ago that I met Haile Sellasie.
The College of Agriculture is at an altitude of 7000 feet.  The weather is what men were designed for.  The lake at the College had oxygen concentration  the same as lake Erie at its worst.  Not because of pollution, it was clean, but because of altitude and temperature.  In the US, High altitude lakes are very cold.  In Africa, 7000 foot altitude means 70 degrees.  Not cold at all.  But this means very low oxygen concentrations.  So fish from Africa, the Tilapias and the Clarius (Walking Catfish) generas have learned to breath air directly.  And this means that fish farmers can raise a lot of Tilapia in a pond that is too small.

VW

VW.

VW builds nice machines.  When I was in Germany on the way to Ethiopia in 1969, I got a used VW mit zwishengasse.  Translation "No Syncromesh" (double clutch).  A fun machine that got us around Europe till the clutch cable broke (easy fix).

Today:  Engines are most efficient at HIGH teperatures. (Diesel Engines are engines). They get the best mileage when the combustion temperature is high. If the combustion temperature is high, and you are using air, nitrogen oxides are formed.  This applies to big power plants also. And truck engines. And stationary engines. And ...

You are building diesel cars. They compete on mileage.  To get the best mileage, you want to run HOT.  The government wants low nitrogen oxides (NOX).  So when the government is watching you should run cool.  When the government is watching, the steering wheel is not moving. Hmm...

So you take out the big brother detecting software.  A third party company quietly  re-installs the high mileage software.  (It is an easy task, should be very cheap).  Everyone is happy again, except the asthmatics who have NOX problems in their lungs.          

Does this flap kill diesels??
Global warming does not see NOX.
We can use airplanes to inject the NOX into the stratosphere.
Maybe wind power is a good idea.