Problem: Determine the dimensions of the cylindrical can with volume v0 and minimum surface (so that we can minimise material cost).
Solution:
So, here comes the interesting question: is a real can really made up of those dimensions?
And the answer is no. This is probably due to the existence of other constraints, such as the strength of can, manufacturing considerations and aesthetics factors.
Let's watch something, kid.
On your radar, be alert!
Look, a missile!
And that is the F-111!
Don't forget about the propeller too!
Aircrafts have heads,
shoulder,
and tails.
The can fly together...
and flip around.
But they need to land eventually.
When the aircraft is on land, someone has to control the traffic.
"Good stuff," said the man.
在一个风和日丽，阳光明媚的早晨，我把研究报告交上。然后就抱着轻松愉快的心情到百货公司去。我是一个对硬体工具感兴趣的人，所以很直然地，我就到了一间号称货廉价宜的硬体专卖店。
当我选好所要买的物品，准备到结账处的时候，我面对着一部机器，一部自动结账系统的机器。首先，机器要求我把物品划过条形码扫描器，然后选择付账方式，再付钱。通常结帐员所说的，所做的都由这部机器代劳。
付账完， 离开百货公司后，我心里有一种莫名的担心。以个人经验来说，自动结账系统是很可行的。它使用步骤简单，估计常人用了两三次后就会得心应手。一来,此系统可减少公司对员工的依赖，减少人为的疏忽；而且长期来看可减少公司开销。所以自动结账系统的普及是指日可待的。当此系统普及的时候，我们不难想象零售业的工作机会会降低。而且结账处也会缺少人性化。然而，系统会不会普及不是我们说了就算的。一般来说，这还得依序“吴竞天择”的原理来进行。
On a bright and sunny day, after finishing the major research report, I went out for shopping. Naturally, like most men, I tend to like shopping for hardwares. Therefore, I went to a store which claimed to sell hardwares cheaply.
After picking up the stuffs that interested me, I go to the checkout and prepare to be served. Guess what? I was faced with an automated check-out system. I was served by a machine.
The automated check-out system was made by NCR, which is a reknown brand for making transaction machines. I was asked by the machine to scan the barcode of the item that I bought (like the check-out staffs usually do), and then put them into a bag (like the check-out staffs always do), and then choose the payment method (exactly what the check-out staffs always ask). Everything that the check-out staffs usually ask or do are asked by the machine.
Although the experience of using this automated system is pleasant, I am a little worry about its implications. For my own experience, I think that the machine is easily operated. Most shopper can cope with it easily and get used to it after a few shopping experiences. If the retailers are keen on using this system, then there would be a reduction in job opportunity in the retailing sector. Some low income earners, including some university students might faced with the loss of job. Automated system is also lack of the kind of personal engagement that you want when you shop. It is inhuman.
In summary, although there are some fallback for implicating the automated system, I believe that the system would be implicated in the near future. As most things, the 'natural selection' always implies. Most product that help reducing operational cost usually wins.
My beloved bicycle elegently lean on a post in Melbourne Central
Some time ago, I was unfortunate to lose a 2.5 year old friend -- my purple mountain bike. The rear wheel axle was found broken.
As an enthused mechanical engineering student, I naturally had some though of the causes of the failure. After the dissection of the rear hub, and carefully examined the broken edge of the axle, I hypothesized that the axle was failed by fatigue due to cyclic bending load.
shiny or grainy broken surface of the axle suggested that the failure was due to fatigue.
Fatigue is a kind of failing mode which happens when cyclic tensile load is applied to the material. Unlike yielding, it can occur below the yielding stress of a material. Also, unlike human, fatigue of an engineering material cannot be recovered by resting.
Side view of the broken axle
Since the an axle was not subjected to torsion, it was unlikely that the axle was failed under torsion load. This hypothesis is also confirmed by the broken surface. If one examined carefully, it can be noticed that the broken surface is flat. Normally, in fatigue under torsion load, the broken surface would be in cone.
Since the bicycle is no longer performing its function due to broken rear axle (in other words, it fails to meet its objective), I cannot sell it. In fact, I would like to sell it, but no one will buy it (at least I had tried the Cash Converters).
So, lets give an honour to my beloved bicycle for its contribution during its life time.
In an attempt to practice my jotting skills, the delivery of this document was expedited. A description of the adventure to Dights Fall would be expected in this document.
The first spot of interest during this trip was Ceres Environment Park. There was a market in the park. Many things were sold there, which includes lots of vegetables.
Some living chickens can be found in the market.
And also some pumpkins.
And also some carrots.
And also some soaps.
During the this trip, many different kinds of track were used. This is track is a track that situated besides the Merri Creek.
We also crossed some bridges.
And climbed some hills.
Belief it or not, we even took a train.
Along the track, some interesting machineries were noticed. This is a wind mill.
This is a crane.
And this is the Merri Creek.
Naturally, when there is a river, there would be some bridges. And this arc bridge is one of them.
This is another bridge. Take note of the interesting structure of this bridge.
At some point, we stopped in the middle of somewhere to take some pictures. (This is why I had so many pictures posted here.)
To prove that I had taken many pictures, I posted this one. Can you see the city from here?
Lastly, we reached our destination -- Dights Falls.
And then, I took some more pictures at Dights Falls.
Before ending the journey, the crew had a lunch at Dights Falls.
The crew members consist of ...
Crew member 1, and
Crew member 2, and
Crew member 3.
[Due to the nature of thing goes, some details of location were deliberately left out.]
