The Tokyo Tunnel - G-Cans

24 August 2010

Introduction
The Tokyo flood tunnels – G-Cans project started construction in 1992 and completed in 2004, about 12 years later. It was just in time to be tested in tyhoon 22 in 2004 when 14 families were reported to be affected instead of 236 families before the completion of the project. The tunnel collects water from Tokyo downtown district and discharge it into the Edogawa river.

The Tunnel
The tunnel is 10m in diameter and about 6.3 kilometers (four miles) long. It is buried 50 metre under the ground in the Tokyo suburbs.

It has 5 concrete silos, each having a diameter of about 32 metres and is about 70 metres tall.

The tunnel is connected to a gigantic water tank measuring about 78m width, 177m long and 25m tall (or 350,000 m3). The tank is propped by 59 numbers of gigantic pillar, each weighing about 500 tons. As the pillars look like those in ancient temples, some named this water tank “the underground temple of Tokyo”.

Connected to this water tank are series of water pump that have a total output of 14,000 hp or 10 MW. They can discharge flood water up to 200 m3 per second or one Olympic pool water in 10 seconds.

The Cost
Estimated to be about US 2.0 billion

The Volume
The tunnel can hold approximately 640,000 m3 of flood water.

Web Query Hangs

23 August 2010

Introduction
Users of Microsoft Excel and other web query software, like IMACROS, often query websites to get the web information for stocks or other purposes. These users will write scripts to automate the process. Sometimes, the process will hang causing lost of data. This article will describe methods to overcome this problem.

Why it Hangs?The process will hang either because the website is down or because the web traffic is high. A webpage usually takes 5 to 6 seconds to download may take up to 10 minutes or even hours.

How to Over come?
The following methods have been tried without much success.

a) Introduce timeout events in scripts or VBAThe script is waiting for a webpage to download and will not activate the timeout under such events.

b) Ping the website before proceeding to download
This will only help if the website is down but it will not help when there is a delay due to heavy traffic.

The better method is to modify the window registry’s internet setting with a timeout of appropriate delay. This is because most browsers use this delay in the internet setting.

http://support.microsoft.com/kb/181050

How to Modify the Registry?
The timeout is not native in the registry’s internet setting. It will have to be created under
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings]. The keyword is "ReceiveTimeout”. Its value will depend on normal delay in webpage download.

The Window default is

Internet Explorer 4.0 and Internet Explorer 4.01 --- 5 minutes
Internet Explorer 5.x and Internet Explorer 6.x---- 60 minutes
Internet Explorer 7 and Internet Explorer 8 ------- 60 minutes

In VBA, add the following code before downloading the data

Set myWS = CreateObject("WScript.Shell")'write registry keymyWS.RegWrite
"HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet " &
_"Settings\ReceiveTimeout", "15000", "REG_DWORD"

The value of “15000” means a delay of 15 seconds. Insert the same code just after the download script and change the value to suit normal surfing.

Error Message for Dynamic Link Library mscvp90.dll

21 August 2010

Introduction
When installing Ad-aware program, one will get the following error message for some PCs:

"procedure entry point?_xfunc@tr1@std@@YAXXZ cannot be located in the dynamic link library MSVCP90.dll "

Why?
This error is due to a wrong version of msvcp90.dll being installed by some programs for some reasons.
The dll is one of the C Run-Time Libraries for Visual C++ and programs such as Ad-aware use them.
According to some descriptions, there are 2 versions of such dll having the same name, msvcp90.dll, one for 64 bits and the other for 32 bits machine. XP operating system is a 32 bit machine.

What Next?If one is using a XP operating system and has encountered the problem.

Step 1: Download the correct version of Microsoft Visual C++ 2008 Redistributable Package (x86) from the following website for XP machines

http://www.microsoft.com/downloads/en/confirmation.aspx?familyId=9b2da534-3e03-4391-8a4d-074b9f2bc1bf&displayLang=en

Step 2 : Locate the directory C:\WINDOWS\WinSxS\x86_Microsoft.VC90.CRTxxxxx. In the directory, one should find 3 Nos of 90.dll files. Rename these files with an extension of .tmp. If one has 2 directories of similar name, do the same.

Step 3: Run the downloaded installation program called “credist_x86.exe”. The installation program will automatically uninstall and reinstall the correct version of 90.dll programs.

Step 4: Locate the directory C:\WINDOWS\WinSxS\x86_Microsoft.VC90.CRTxxxxx again. One will find the new 90.dll programs. Copy all the 3 programs to “c:\windows\system32”

Marina Barrage - Fighting With Nature

Introduction
There was recent spate of flooding in Singapore. The famous Orchard Road was under 300 mm of water. Some blamed the Marina Barrage that was completed 3 years ago. This article will examine how the barrage works and if it can alleviate flooding in low-lying areas.

The Marina Barrage
The Marina Barrage (Chinese:滨海堤坝) is a 350 metres low level dam in Singapore built across the mouth of the bay, between Marina East and Marina South. It was officially opened on 1 November 2008.

The barrage serves 3 purposes:-
a) Provide Water Supply
b) Perform Flood Control
c) Lifestyle Attraction

The video about the barrage can be found here

How the Barrage Works?

During heavy rain, the series of 9 crest gates at the dam will be opened to release flood water into the open sea when the tide is low. The 7 Nos of 40 m3/s (about 2.5 MW @ 3.5 m head) pumps, capable of pumping an Olympics-size swimming pool per minute will work when the tide is high. This mechanism is supposed to alleviate flooding in the low-lying areas in the city such as Chinatown, Boat Quay, Jalan Besar and Geylang.

The video of the crest gate and the pumps can be found here and here.


The Marina Basin



The Marina Basin has a surface area of about 240 ha (240,000 m2). It is linked to a 100-km2 rain catchment area shown green in the attached model. During raining days, the drains and canals will channel the flood water into the Marina Basin.


The flood
A series of flood occurring after the Barrage was completed



Can the Marina Barrage Cope?
The Barrage and the basin will not eliminate flooding totally if there is a very heavy downpour and the tide is high. This is because the rain fall from the water catchment, if more than those on 17 July, may raise the water level Marina Basin by more than 4.0 metres (discounting the retained water on the surface of the catchment and the buffer in drains/canals/river) during a heavy downpour as shown in table 1.

2o August 2010
What Can We Do?
a) Reduce the Water Catchment Area
If we were to reduce the catchment area by 40%, this will reduce the water level rise in the basin by about the same proportion to 4.5 metres per hour without pumps and 4.0 metres per hour with pumps in full operation. The alternative is to regulate the flood water flow from higher areas.

b) Allow More Buffer Capacity In Basin
With the present barrage, there is a limit on how much a buffer can be created in the basin because the gates are not totally water tight. There will be seawater leeching into the basin if there is large difference in the level of water in the basin and the open sea; also, the pumping electricity cost would be high if we keep the water level in the basin low.

Reducing the water catchment area appears to be a better of the 2 solutions for the present setup at the Marina Barrage.