What’s Wrong With this Chart?

25 January 2014

Introduction

Shown in the chart are the DOW’s Transportation Index (^DJT) and DOW’s Commodity Index (^DJC) superimposed over the past 20 years.  There are obvious divergences and convergences between the two index.  Divergences usually happened just before any crisis and the index will converge soon after that.  Recently,  we see divergence with  ^DJT taking off mid 2011 and ^DJC going the other direction.   Lets examine closely what are the causes and  implications

Relationships Between

DJC and DJT

DJC is an index that tracks all the commodity futures that are traded in US.  DJT much Like DJI, the DOW JONES Industrial Index, consisted of about 20 US companies such as FedEx that deal with airline and rail transportation. 

As more produce like iron core, corns etc come on-stream,  more transportation will be needed.  Rightfully speaking,  the better the performance in DJC,  the better will be the performance of DJT and vice versa.  However,  there are rare occasions that over production causes  commodity prices to slump and affects only the commodity price index;  similarly,  a rise in fuel cost will cut transportation companies’ profit.

DJT and DJI

Some argued that DJT was more related to DJI than DJC.  This is because companies in DJI rely on transportation shipments to stock and sell their goods.  When DJI companies anticipate a positive performance, they will increase production of goods that will be needed to be transported between different outlets.  The two indexes inter-twine each other most of the time.

Actually,  DJI,  DJT and DJC are in a value chain except DJC is based on commodity futures indexes whereas DJI and DJT are based on stock prices of the companies.  If the external factors such as QEs are removed,  these 3 indexes should go hand in hand.

Present Development

As can be seen from the chart,   DJT took off mid of 2011 whereas DJC went the other way.  It is obvious that DJT is tracking along with DJI  whose prices have been affected by Bernanke’s QE programs.   

Why?

One reason could be because US are still heavily depended on import of commodities and the production of commodities overseas are more affected by supply and demand rather than the US’s QEs.

Where would the Prices go?

The chart shows that ^DJT and ^DJC wondered around sometimes but they always  converged and move in tandem afterwards.  It can also be seen that whenever there is appreciable divergence between the two indexes,  a recession soon follows;  they will  converge again by the time the recession is over. This happened in around year 2000,  2008 and mid 2011.  Year 2011 was an exception where an intended recession was saved by Bernanke's Operation Twist and QE3.

We are now in year 2014 where one can see the great divergence again between DJT and DJC.  It is therefore likely that these 2 indexes will again converge in the future.   But before the  convergence,  would we not see another recession?

Sealing of Openings for Window Unit Air Conditioner

22 November 2013

Introduction 

Some high rise apartments in Singapore, especially those older types, are in-built with openings for installation of window type air conditioning unit.   With the advent of inverter split air conditioning unit that can save energy,  many apartment owners have converted from the windows unit  to split air conditioner unit.  The AC installer will simply seal up the window unit openings and walk away,  leaving the owners having to face all sort of maintenance problems.  This article will describe how best to seal these openings.

What’re the maintenance problems?

The AC installer will usually seal the opening with a nice painted 3 mm plywood board,  nailed on the timber frames from inside the apartment.  This board will rot in time and allow rain water to sip onto the carpets or parquet floorings during heavy rains.  A small ledge left outside will attract not only birds to nest but also small plants to grow;  also,  the thin plywood board offers no security as they can be easily kicked open. 

What're needed? 

1. A piece of 20 mm thick plywood to cover up the hole;
2. One lots of about 30 numbers of 30 - 35 mm self-taping screws;
3. 4 number of 100 mm self taping screws
4. Few  lengths of 25x25 timber strips
5. Weather sealing strips
6. Necessary tools such as power drills,  drills,  screw drivers etc..

What precautionary measures?

Assuming that one would have to fix the heavy 20 mm board from inside the apartment to cover the opening from outside the apartment,  one necessary measure is to ensure that the board would not accidentally drop and hit some passerby beneath the openings.   This can be done by fixing ring hooks onto the board and tie strings to hold the board throughout the installation.

Installation steps 

1. Cut the 20 mm plywood to a size slightly larger than the hole;
2. Fix the ring hooks and strings,  then put board to the hole and mark up the size of the hole on the board;  alternatively, one can measure the hole and mark the board;

1. Remove the board and cut 4 number of the 25x25 timber strip to  place them exactly in the inner dimension of the opening and screw the timber strip to the board;
2. Protect the board by painting water proofing paints or seal it up with weather board or otherwise to prevent water coming into contact with the plywood;
3. Place weather sealing strip around the 4 sides of the board;
4. Prepare 4 numbers tensioner and install them onto the timber frame as shown,  making sure that the 100 mm screw is free to move and can be screw onto the 25x25 timber strips;
5. Fix the board in place and screw the 100 mm until the board is pulled in and sit tightly fitted to the timber frame with the weather sealing strip fully compressed to form the water seal;
6. Fix the 25x25 timber strip to the timber frame and remove the tensioners if necessary.

The Completed Work 

Makita Cordless Power Drill DC7100

20 November 2013

The Makita Cordless Power Drill is a handy tool.  Its power unit consists of a 7.2 volt battery pack and a fast battery charger.   This article describes how to replace the battery and repair the battery charger.

 What’s Needed

1)     For replacement of battery 

a)     Soldering iron,  solders and some connecting wires

b)     4 Nos  of 18650 Li-ion batteries.  Can also use some of the good batteries in Laptop for this purpose

 

c)     Remove the end cap of the battery pack and withdraw the batteries

d)     Solder the 18650 batteries,  2 in parallel then put them in series to make up a total voltage of 7.4 volts.  Pay particular attention to positive and negative battery terminal and make sure there are correctly wired;  also pay attention to how the resistor is connected. 

e)     Once soldering is completed, wrap the batteries with shrinkable plastic and re-assembled the batteries to the battery pack casing.

2)     For repair of the power charger 

In addition to the soldering iron,   one will need a multimeter that can measure the workings of the A1015 transistor and the 2P4M SCR thyristor.  These 2 components are likely to be at fault.  .  One would need knowledge of electronic repairs for this task.  Use the attached circuit diagram to troubleshoot.

2P4M Thyristor

Watch the US Banking Index $BKX

13 September 2013

DOW has since improved its position.  It made a 3 white soldier pattern on Tuesday as shown in the attached.  This was mainly because Obama had deferred his decision to use military force in Syria. 

DOW suffered a small pull back as expected after having formed the 3 white soldier pattern.  DOW should regain its position when the prevailing conditions remain.  However,  no jump in DOW will be seen until the banking index,  $BKX, can improve the position.

As shown,  the $BKX has recovered slightly since end August but not as strong as DOW.  It has tested the 50% of RSI on Tuesday but failed to cross over it last night.  Although its stochastic and MACD shows bullish formation,  it is getting weaker.  The consolation is that the 50-day MA is still trending up which means that there is still a chance that  $BKX will improve and continue to play  the leading role. 

10 August 2013

Introduction

In May,  it was pointed out that the US Banking Index will lead the falls of US stock market.  That index has since broken the 4 year high as well as the upper channel line that bounced the price from mid 2012.  It is heading to test the 5 year high.

Why the Banking Index?

The rise and fall of US stock market are always credit related.   The relationship is even stronger this time with the rampage of QEs. The May article has indicated that the banking index,  $BKX, will lead the market fall.  It is therefore important to pay attention to this Index.

What's the Performance?

As shown in the chart above,  $BKX has broken the 4 year high and is going to break the 5 year high.

The following chart that compares the indexes of DOW and $BKX will show that $BKX is leading the DOW,  jumping up since Mid June and showing little sign of fatigue. But the fall of  $BKX have just been confirmed last Friday.  DOW's fall was confirmed mid last week.

What is the Macro Picture?

After having formed the bearish Harami on 2 August,  $BKX has 3 subsequent downfall days confirming the Harami candlestick.  It has created also a candlestick gap on the 3rd day which was quickly covered on the 4th day by a doji,  on 8 August.  The fifth candlestick last Friday confirmed the down trend.  Because the confirmation was weak,  there might be a possibility that $BKX will want to retest this support turned resistance line.  Should that fail,  $BKX will head to break the 50MA and cover up the candlestick gap created on 5 July 2013.

Going Forward 

It may be good to pay attention to the development in $BKX and check regularly if $BKX will lead this great fall in the US stock market.

The Hang Man Candlestick; is it dangerous?

5 August 2013

Introduction 

A hangman candle stick appeared last Friday in DOW.  It has long lower shadow and a small head,  resembling a hammer.  

 

What is a HangMan ? 

It is called a hangman and not a hammer because it is a bearish sign.  If it is confirmed,  it can often bring stock market to its knees before it could recover again.

Hangman reversal patterns are often seen on the very top of the uptrend.  There are many reasons why hangman is so bearish.  Many explain that it is because the uptrend is almost exhausted and the bulls are losing control for various reasons.

What has happened?

This present uptrend is driven all along by QEs.  When Bernanke announced the thinking of QE tapering in May,  the market responded with an immediate sell down.  The 10 year treasury yield jumped more than 10% in a single day.    

Although Bernanke and other FED members talked up the market in July,  many Wall Street analysts and bankers still hold the view that FED would  start QE tapering in September this year and would end QE next year because:- 

a)  Bernanke's tapering was based on US economy to turn better in September and also unemployment rate to be  lowered to 6.5% next year.  No one in a clear mind would believe him because of the slowing growth in China and all over the World;

b)  On the contrary,  most analysts believe in what Mr. Mohamed El-Erian, the CEO of PIMCO,  had said about "less positive reason" for tapering which is the side effect of QEs.  Mr.  El-Erain thinks that FED is tapering because it has started "to get more and more worried about what Mr. Bernanke has called the costs and risks of prolonged unconventional and experimental policy".

As money are easily available for tradings,  Funds and Bankers often use derivatives for hedging purposes to protect their trading investments or as part of their investment strategy.  These derivative tradings involve risks and the portfolios investing in derivatives could lose more than the principal amount invested.

For example,  after Bernanke announced its intend to taper QE,  USbond yield jumped. This has caused many Hedge Funds and Bankers to lose $billions over night.  Pimco Bond Guru Bill Gross admitted the Fund has lost about 4% of its $265billions PIMCO Fund requiring the need to withdraw about $10 billions to make up the losses.

Treasury bond derivative is only one of the larger ones played by the Hedge Funds and the Bankers. It was estimated that the bet on interest rate derivatives had reached about $400 Trillions and the total sum of the derivative trading has exceeded $700 Trillions Worldwide and expanding at a rate of about 30% per year.

Is this DOW's Hangman Candlestick Dangerous?

This  occurrence of  Hangman is considered dangerous because it happened right after the FED's tapering announcement where the jump in Treasury yield had caused a lot big Funds and Bankers to lose money.  They would have to find money to make up the losses.  Although DOW has managed not only to regain its losses but also making another new high,  it would not help to cover up the loss bets in the Treasury bonds.  DOW has gone flat since 22 July with many trading days having sold off at the start and recovered only at the end of the trading sessions.  This trading pattern was a common sight during the 2007/2008 market when market was topping and bulls are running out of "bullets".

Will We Need  a Confirmation Signal?

Hangman candlestick pattern is often considered less reliable reversal signal in a way that the bulls are still actively engaged in the trade;  therefore,  there is a need to see a strong down day in the following trading days for confirmation.   Should this pattern be confirmed,  it can often bring the stock market to its knee before it can recover again.  The confirmation should be either a gapped down or a long red candlestick or a combination of small down days.

Update 1:  8 August 2013  Hangman is Confirmed

 

After having formed the hangman,  DOW was been slow in confirming the bearish pattern.  It took a total of 3 down days and finally,  confirmed reluctantly with a weak down candlestick as it broke the supporting line.   May be many investors are still hopeful that QE tapering will not come.  Because of the weak confirmation,  these hopeful investors may retry to re-capture loss ground if there is an opportunity.  The real downward movement will come only when the retries failed to go above the supporting line as shown.

In the weekly chart,  DOW has also formed a breakaway bearish pattern yet to be confirmed as the week is not over. It will aim at covering up the 2 small candlestick gaps as shown.   Similarly,  a bearish engulfing is beginning to take shape in the monthly chart.

Q&A

Why not check S&P, Nasdaq and other Charts

Traders should not just refer to one chart alone for trading.  As this blog is for learning and not for trading purposes, it would leave it to the traders to do their homework.  Since there is this question,  it would be good to examine the other charts;  for example,  S&P and Nasdaq.  It would appear that both S&P and Nasdaq have been affected by the hangman in DOW.  Both S&P and Nasdaq's fall have not been confirmed

S&P

Nasdaq

Update2:  20 August 2013

After having formed the hangman candlestick,  DOW went ahead to break the 50 MA last Thursday and broke the 100 MA yesterday as shown in the following chart.

DOW has also broken 2 necklines;  1st,  last Thursday when DOW broke the 50MA and yesterday, when DOW broke the 100MA.    When DOW broke the 1st neckline last Thursday,  the volume was not high and therefore,  that Head and Shoulder pattern was  not confirmed.  As for the present neckline2,  the volume is again low as Monday is usually a low volume day.   However,  it was observed that there are many call options still trapped in the system and they will stop trading this Friday.  It is expected that volume will pick up and this would confirm the second neckline.  Once that were to happen,  DOW will head towards to test the 200MA line.

Update 3 :  23 August 2013 - Bullish Harami Spotted;  Will this reverse the trend?

After several days of down trend with DOW losing about 6% or 800 points,  a bullish harami candlestick is finally spotted.  Yesterday,  Germany announced better than expected manufacturing  PMI figure of 52 whereas US had bad economy figures with retail sale and jobless claims below expectation.  The investors cheered and started the buying spree with US investors hoping that QE will not be tapered.  But will this bullishness continue in the US and for how long?

The following chart will show that DOW has been oversold with the stochastic showing signs of recovery. A Harami candlestick is spotted but this one is not as strong as those having a much smaller body in the second day. 

As this dip is much worst that the previous ones and the Harami spotted is not very strong; also unlike the previous occasions,  the US 10 year yield is at 52 weeks high,  it is advisable to wait till the MACD histogram to hit positive before entering the market as shown in the chart.

How Fast Exactly is the Solid State Drive?

4 July 2013

Introduction

We have an Acer 4755G notebook which has a Core i5 processor with 8 GB of memory.  It is been running on 64 bits Windows 7 operating system.  After we have changed the hard disk from 750GB Western Digital magnetic drive to 250 GB SamSung 840 series solid state drive (SSD),  we immediately notice the notebook reads 6 times and writes 3 times faster with almost instant connection to internet pages.  It boots up in about 20 seconds which is 1/2 of the time taken.   This article will describe how it is done and what is the test results. 

What you need?

1.  A software transfer program;

2.  A small screw drivers;
3.  Plenty of readings.

Before Starting Work

1.  Check that your computer/ notebook's BIOS has an  AHCI interface for the disk drive.  SSD will only work well with AHCI interface although IDE interface will also work at slower speed.

2.  If the existing hard disk (referred as old hard disk)  is running off an IDE interface,  then there is a need to re-configure first the old hard disk  to run on AHCI interface.  If one should get a blue screen of death (BSOD) after changing the interface to AHCI or vice versa,  consult the following microsoft  website .

Transferring Programs from Old Hard Disk

This is the most tedious part of the work and time consuming.  It may take up the whole day.  It involves also copying the operating system.   If one has the notebook which has only one hard disk slot ,  there are 2 choices:

1.  Using SamSung SSD Magician Software 

The SamSung SSD Magician comes as a package in a DVD. Mount the SSD on an external hard disk enclosure or adaptor for  SSD drive (such as the adaptor that comes with the package if it is included).    One can also download the Magician from the SamSung's website.

If the SSD is new,  it may need to be configured first using Windows' Dsk Management tool;  otherwise,   SamSung Magician might not be able to find the SSD drive.   To open Disk Management,  goto Control->Adminstrative Tools->Computer Management,  then select Disk Management. 

2.  Using Commercial Transfer Software

Software that can clone hard disk can be used also to transfer the programs.  If one just has an ordinary external hard disk enclosure that does not allow proper cloning of SSD drives,  the only alternative  is to backup the partitions of the old hard disk to an ordinary external hard disk. After that,  replace the old hard disk in the computer/notebook with the new SSD and then copy or recover back the partitions one by one. 

If one's computer has an extra hard disk port that can offer AHCI interface functions,  one can hook up the SSD as second drive and use any transfer software that can clone the hard disks to transfer the entire hard disk program including the operating system. 

3.  Installing New Operating System

 

Some prefer to install new Windows Operating System on SSD.  Windows 7 has a program under Accessories>System Tools that will allow one to make a copy of programs to be transferred from old hard disk to new hard disk or old computer to new computer.  One will need an external  hard disk space of about the same size of the programs to be transferred. 

Before starting to install the new Windows Operating System,  save a copy of the existing program.  This can be done easily using Windows Easy Transfer.   Start up Windows Easy Transfer and select "Old Computer" to copy the programs to external hard disk.  Click the "custom" wording and in the "Advanced" menu,  check all the check boxes if one wants to transfer all the programs; otherwise,  select only the desired ones. 

The whole process may take up to 1 hour depending on the size of programs to be transferred.  After the SSD is installed with the new Windows operating system,  transfer back the programs as instructed by Windows Easy Transfer.

Things to Watch out

1) Before replacing the old Hard Disk, make sure to delete all the unwanted and obsolete programs so that the total capacity of all the partitions added up together or the partition to be copied is less the capacity of the new SSD drive;

2)Ensure again that the existing hard disk is running on AHCI and not IDE hard disk interface.if you use method 1 or 2.  When installing new operating system in method 3,  set the BIOS to run hard disk on AHCI first before installing the operating system.

Where to find the hard disk in notebook? 

The hard disk is usually hidden inside and underneath the notebook.  One would have to remove the hard disk cover for replacement.  Note that some notebook has warranty seal on the cover screws.

What to do if the SSD does not perform to expectation?

There are many reasons.  But if there is an AHCI interface,  the following steps might be of some help. 

1) Tweak the computer using available software provided by the SSD manufacturer;  for example in the case of SamSung SSD,  use  "Performance Optimization" and "OS Optimization" to optimise the performance,  then  use the  "Over Provisioning"  and "Shrink (default value)" to shrink the start up partition (which usually is c:) so that SSD will work more efficiently; 

2) Check if the TRIM function of Windows 7 is turned on by the following step by step method:-

a) Open up Command Prompt by typing "CMD" in the start up search bar and run CMD as administrator;

b)  In the Command Prompt,  type "fsutil behavior query DisableDeleteNotify".   The  result  "0" indicates that TRIM is enabled correctly.  If the result is "1" or otherwise then type

"fsutil behavior set DisableDeleteNotify 0"  in the next command prompt. This will change the result to "0" and enables the TRIM; 

3)  It may be necessary to carry out the following additional modification works:-

 a)  Turn off hibernation function

At the command prompt,  type "powercfg -h off" to turn off the function 

b) Turned off drive indexing in C drive

Click "Computer" in start button menu.  In the C: drive,  right click "properties" and then uncheck "allow files on this drive to have contents indexed.." 

c) Switch "Power Option" from "balanced power"  to "high performance";  alternatively,  to use mains power to over write the power option for computer to perform at "high performance"

To prevent unnecessary "garbage collection" by SSD and degrade performance over time,  it would be wise to customise the  "Pagefile" in the "Advanced System Setting" of "COMPUTER" from "system manage"  to 100 MB min/1000 MB max.

Test Results 

The following compares the performance of ACER 4755 before and after the conversions.

The AS SSD Benchmark software can be downloaded here.  The results shown that there are appreciable differences between the 2.   The old hard disk took too long to complete the test and has to be terminated.

DIY Mosquito Screens

28 June 2013

Introduction 

Dengue is the  name of a disease spread by a special mosquito called aedes mosquito. 

To date,   It has claimed 4 lives in Singapore.  It is also a common disease in Philippines,  Malaysia and other countries in South East Asia.  So far,  there is no cure or drugs for treating dengue;  doctors will just prescribe pain killers and make observation for life threatening signs. This article will describe the experience that the author has had fighting against Dengue.

How To Prevent? 

The only way is to avoid a mosquito bite but it is easily said than done as mosquito is everywhere.  The common knowledge is to eradicate the mosquito breeding grounds.  NEA (National Environment Agency) found 80% of breeding grounds are actually right at home.  This however does not prevent one from mosquito bites because there are so many breeding grounds out there in the natural habitat that cannot be easily eradicated. 

The only effective way the author has found is to install mosquito screens at home and wear repellents outdoors to prevent contacts with the mosquito.  The article will concentrate on how to install these mosquito screens DIY and save money. 

Why the Screen?

1.  It is a permanent measure that will save "tons" of insecticides which is not only  harmful the environment but also the human beings;

2.  It cost next to nothing to maintain;  only occasional cleaning is required;

3.  It does not block out much sunlight and ventilation;

4.  It is aesthetically pleasing as screens are almost transparent;

5.  One can repair the screen easily using thread and needle

How Many Type of Mosquito Screens? 

There are many types of mosquito screens available in the market;   roughly,  they fall into 2 categories; the fixed and the removable type. 

The fixed type can often be done as simple as using construction plastic coated green mesh or net available from many local hardware shops;  the more sophisticated one will use special woven net materials.  They come in a roll form.  Some plastic coated green mesh can be quite brittle and are not suitable for screen making because they will tear easily during installation;  the better ones are woven type.  They all look about the same but the woven ones are thinner and has fibre threads.

The removable ones are mainly of woven net materials except it is first fixed onto a specially made PVC trunking and then attached to plastic magnets so that they can be removed at will for cleaning for example.  As there is a video made for the removable type,  this article will concentrate on how to install the fixed type.

How to DIY using Construction Mesh/Net?

To install the wire mesh onto the wooden window frames,  one can use small timber strips and a staple gun. 

Cut a piece of mesh slightly bigger than the opening and fix into position with timber strips; thereafter staple the timber strips onto the window frame with the staple gun. Making sure that the timber strip is thick enough to fit the staples to let it stapled onto the wooden frame.

To install the wire mesh to metal frames or concrete wall would require having to fix first and screw a small timber frame onto the metal frames or concrete using electric drill and fixing screws.  After that,  one can use the same method as fixing the mesh to the timber frame as described earlier.

How to DIY using Woven screens

These woven screen comes either with honey cone or square net form. 

They are stretchable and can be hooked onto velcro strip that usually come as a package as shown.  They will cost around USD$2/= from ebay suppliers directly delivered to your door steps.

The fixing is relatively simple and quick.  The velcro is first fixed onto wooden or metal frame work after having first cleaned the surfaces with industrial thinner or equivalent;  thereafter,  just lay the screen over without stretching and press the screen onto the hook of the velcro.

The trick for successful installation is NOT to stretch the screen when laying it over the opening.  Stretching the screen will cause undue pulling force on the velcro which can become detached easily,  leaving a hole;  then the only way to re-fix the velcro in position is to staple it using the staple gun.

Mosquito Screen for Sliding Windows

Most of the windows today are sliding type.  There are 2 ways to fix mosquito nets.  One is to fix it external either directly onto the window grilles or metal mesh or to construct a wooden frame as big as a window panel.  Fix the screen first onto the timber frame using the same methods described above then mount the screen as if it is one of the windows.

Sliding Screens for Doors

The screen for the door will be a bit harder to construct because it will involve a sliding type of screen. However,  one can construct the screen door cheaply using an aluminium or timber frame to slide it along a window curtain rail as shown. 

Allow horizontal and vertical adjustment in the brackets holding the curtain rail to get a smooth sliding.  There will be a need to install a pvc strips on the floor next to the screen door as a stopper to prevent screen door from swinging in and out or to and fro when the wind blows.

The curtain rail is easily available from any hardware store.  A sliding screen door can be made within a day or two for less than SGD$30/= ( $ 15/= for the aluminium frame,  $ 10/= for the curtain rail and $5/= for the screen and the angle brackets or stiffeners.)   If aluminium frame is used,  just glue the screen onto the aluminium frame and trim the edges after having the ugly glue parts concealed by using special timber strip of 5 to 10 mm width (from Diaso IMM store or Art's Friends at Bouna Vista MRT station).   

There are also special curtains made for the door and they are available for ebay.  The curtains have  magnetic strips on the opening edges to seal the curtains.

.

 Q & A

 

1. Will the screens cut out natural lights and ventilation?

The mesh or net will cut not much lights and ventilation. The normal construction green mesh may cut by less than 10%;  the woven screen,  by less than 5%. The woven screen is almost transparent viewing from a distant of more than 2 feet away.  

 2. Wouldn't mosquito still get in through the doors?

Mosquito will like to rest on dark surfaces,  especially when the doors are colored dark. When one opens the door,  it is very likely for mosquito to be "blown" into the house by the "wind" of the door.  One way to prevent this is to have light colored doors;  the alternative is to place mosquito repellents near the door way and renew the repellents every now and then when they expire. 

3. Would the screens trap dust?

Yes.  Some dust will accumulate over time but vacuum cleaning will keep them clean again.

4.  I bought the woven type with velcro from ebay.  How do I hide the ugly edges?

The screens come with a 5 mm velcro strip which can be an eye sore when the screen's edges are untidy.  One good way to hide the ugly edges is to cut another velcro strip and press it onto the original velcro;  the alternative is to buy small 20 mm x 10 mm or smaller trunkings meant for electrical wiring to cover up the edges.  Fortunately,  only the windows at the corridor are exposed and need the edges to be covered up.

5.  Must we ensure that all openings are protected? Some are difficult

All openings in the house must be protected,  even the openings leading to open yards and door ways.  It will be useless to protect all windows and leave the doors open.  Install door closing device if needed be to ensure the doors will be closed at all time and also double quick.  There will always be a way to seal the openings.  Discuss this over with your carpenter or home builder

6.  Why do we need stiffeners for the sliding door screen?

The sliding door made from 12 mm square aluminium box section will be very unstable for a screen door of about 2.2 metre tall and 1.5 metre wide.   Stiffeners and angle plates plus cross bars will need to be added to ensure the screen door would not wobble.

7.  How to Prevent Sliding Door Screen from Swinging?

The sliding door screens made from aluminum frame are quite light and will swing if there are strong wind.   To hold down the frame,  one would need a floor track for the door.  The author used a long piece of 3/4" width telephone trunking as the floor track and 2 Nos of 5 mm stainless steel ball bearings as door slider at each end of the door screen as shown

Cut 2 short piece of aluminum channels and drill 2 holes on each piece.  The hole shall be made just slightly smaller than the diameter of the ball so that it will hold the ball in between the channel and the door frame.  After ensuring the ball bearing is free to move,  fit the aluminum channels and ball bearing to the screen frame using rivets.  (Tip: One can start drilling the hole one size smaller than ball diameter and use hole reamer tool or round needle file to enlarge the hole)