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3/17/11

World's Most Disasters

Workers load the carcasses of horses into a truck at an equestrian 
club in Mexico City on August 26. 
Heavy rain caused floods, drowning at least 50 trapped 
horses and killing a night watchman
A huge tornado funnel cloud touches down in Orchard, 
Iowa, on June 10, at 9:04pm

The broken spillway of a vanadium mine is seen in Shanyang county, 
Shaanxi province, China, on July 22
This September 10 image, taken by the crew of the International Space Station 
flying 220 statute miles above Earth, 
shows Hurricane Ike
In this September 12 photo, a home burns on the beach on Galveston Island, 
Texas, as Hurricane Ike approaches
People seek refuge from flood waters in east
In this October 13 photo, traffic snakes up a road as 
residents flee their hillside homes
The Chaiten volcano in Chile erupts during storms in the 
middle of the night on May 3
A soldier on the banks of the Rio Blanco looks at a cloud of ash from the 
Chaiten Volcano in southern Chile on June 25
An aerial photograph captures the plume of ashes spewed by 
the Chaiten volcano in Chile, on May 31

WORLD TRADE CENTER - SOME ENGINEERING ASPECTS


Why WTC fall....some sayi it was attackted by terrorist... 
but some say it just way to blame Islam people 
and some say that it because of engineering aspect... Let read this....


World Trade Center
Height: 1,368 and 1,362 feet (417 and 415 meters)
Owners: Port Authority of New York and New Jersey.
(99 year leased signed in April 2001 to groups including Westfield America and Silverstein Properties)
Architect: Minoru Yamasaki, Emery Roth and Sons consulting
Engineer: John Skilling and Leslie Robertson of Worthington, Skilling, Helle and Jackson
Ground Breaking: August 5, 1966
Opened: 1970-73; April 4, 1973 ribbon cutting
Destroyed: Terrorist attack, September 11, 2001

The Structural System

Yamasaki and engineers John Skilling and Les Robertson worked closely, and the relationship between the towers’ design and structure is clear. Faced with the difficulties of building to unprecedented heights, the engineers employed an innovative structural model: a rigid "hollow tube" of closely spaced steel columns with floor trusses extending across to a central core. The columns, finished with a silver-colored aluminum alloy, were 18 3/4" wide and set only 22" apart, making the towers appear from afar to have no windows at all.

Also unique to the engineering design were its core and elevator system. The twin towers were the first supertall buildings designed without any masonry. Worried that the intense air pressure created by the buildings’ high speed elevators might buckle conventional shafts, engineers designed a solution using a drywall system fixed to the reinforced steel core. For the elevators, to serve 110 stories with a traditional configuration would have required half the area of the lower stories be used for shaftways. Otis Elevators developed an express and local system, whereby passengers would change at "sky lobbies" on the 44th and 78th floors, halving the number of shaftways.

(Taken from www.skyscraper.org)

The structural system, deriving from the I.B.M. Building in Seattle, is impressively simple. The 208-foot wide facade is, in effect, a prefabricated steel lattice, with columns on 39-inch centers acting as wind bracing to resist all overturning forces; the central core takes only the gravity loads of the building. A very light, economical structure results by keeping the wind bracing in the most efficient place, the outside surface of the building, thus not transferring the forces through the floor membrane to the core, as in most curtain-wall structures. Office spaces will have no interior columns. In the upper floors there is as much as 40,000 square feet of office space per floor. The floor construction is of prefabricated trussed steel, only 33 inches in depth, that spans the full 60 feet to the core, and also acts as a diaphragm to stiffen the outside wall against lateral buckling forces from wind-load pressures."

Taken from www.greatbuildings.com
World Trade Center plan
Typical Floor Plan of the World Trade Center

A perimeter of closely spaced columns, with an internal lift core. The floors were supported by a series of light trusses on rubber pads, which spanned between the outer columns and the lift core.

Why Did It Collapse?

Tim Wilkinson, Lecturer in Civil Engineering

(This is an initial suggestion, originally written on Sept 11 2001 (with some minor subsequent changes) on one possible reason for failure, and should not be regarded as official advice.)
World Trade Center collapse
The structural integrity of the World Trade Center depends on the closely spaced columns around the perimeter. Lightweight steel trusses span between the central elevator core and the perimeter columns on each floor. These trusses support the concrete slab of each floor and tie the perimeter columns to the core, preventing the columns from buckling outwards.

After the initial plane impacts, it appeared to most observers that the structures had been severely damaged, but not necessarily fatally.

It appears likely that the impact of the plane crash destroyed a significant number of perimeter columns on several floors of the building, severely weakening the entire system. Initially this was not enough to cause collapse.

However, as fire raged in the upper floors, the heat would have been gradually affecting the behaviour of the remaining material. As the planes had only recently taken off, the fire would have been initially fuelled by large volumes of jet fuel, which then ignited any combustible material in the building. While the fire would not have been hot enough to melt any of the steel, the strength of the steel drops markedly with prolonged exposure to fire, while the elastic modulus of the steel reduces (stiffness drops), increasing deflections.
World Trade Center collapse
Modern structures are designed to resist fire for a specific length of time. Safety features such as fire retarding materials and sprinkler systems help to contain fires, help extinguish flames, or prevent steel from being exposed to excessively high temperatures. This gives occupants time to escape and allow fire fighters to extinguish blazes, before the building is catastrophically damaged.

It is possible that the blaze, started by jet fuel and then engulfing the contents of the offices, in a highly confined area, generated fire conditions significantly more severe than those anticipated in a typical office fire. These conditions may have overcome the building's fire defences considerably faster than expected. It is likely that the water pipes that supplied the fire sprinklers were severed by the plane impact, and much of the fire protective material, designed to stop the steel from being heated and losing strength, was blown off by the blast at impact.

Eventually, the loss of strength and stiffness of the materials resulting from the fire, combined with the initial impact damage, would have caused a failure of the truss system supporting a floor, or the remaining perimeter columns, or even the internal core, or some combination. Failure of the flooring system would have subsequently allowed the perimeter columns to buckle outwards. Regardless of which of these possibilities actually occurred, it would have resulted in the complete collapse of at least one complete storey at the level of impact.

Once one storey collapsed all floors above would have begun to fall. The huge mass of falling structure would gain momentum, crushing the structurally intact floors below, resulting in catastrophic failure of the entire structure. While the columns at say level 50 were designed to carry the static load of 50 floors above, once one floor collapsed and the floors above started to fall, the dynamic load of 50 storeys above is very much greater, and the columns at each level were almost instantly destroyed as the huge upper mass fell to the ground.

(US readers note: storey is the Australian/English spelling of story)
World Trade Center collapse
Sydney Morning Herald graphic adapted from the information on this page.

When this article was first written on 9/11, the only evidence Was photographs and television footage. Whether failure was initiated at the perimeter columns or the core is unknown. The extent to which the internal parts were damaged during the collision may be evident in the rubble if any forensic investigation is conducted. Since the mass of the combined towers is close to 1000000 tons, finding evidence will be an enormous task.
World Trade Center collapse
Perimeter columns, several storeys high, and still linked together, lie amongst all the debris on the ground.
World Trade Center collapse
This photograph shows the south tower just as it is collapsing. It is evident that the building is falling over to the left. The North Tower collapsed directly downwards, on top of itself. The same mechanism of failure, the combination of impact and subsequent fire damage, is the likely cause of failure of both towers. However, it is possible that a storey on only one side of the South Tower initially collapsed, resulting in the "skewed" failure of the entire tower.

While the ways the two towers fell were slightly different, the basic cause is similar for both - a large number of columns were destroyed on impact, and the remaining structure was gradually weakened by the heat of the fire. Not much significance should be taken from the fact that one tower fell in 45 minutes and the other in 90 minutes.

The gigantic dynamic impact forces caused by the huge mass of the falling structure landing on the floors below is very much greater than the static load they were designed to resist.

Other Theories?

This section added 14 January 2006

This website generates many queries from people in response to some of the other theories that are put forward relating to the collapse - namely that it was a controlled explosion.

The initial impact/further weakening by fire reasoning is based on uncontestable knowledge about the behaviour of structures in general, and the weakening of steel under fire conditions, plus video footage of the events and examination of the steel afterwards. The official FEMA report written by engineering experts came to this conclusion based on the evidence.

However, should additional evidence come to light that supports a different theory, the author is willing to reassess his views.

The fire wasn't hot enough to melt the steel
There has never been a claim that the steel melted in the fire before the buildings collapsed, however the fire would have been very hot. Even though the steel didnt melt, the type of temperatures in the fire would have roughly halved its strength.

There would have been variations in the distribution of the temperature both in place in time. There are photos that show people in the areas opened up by the impact, so it obviously wasnt too hot when those photos were taken, but this is not to say that other parts of the building, further inside were not hotter. In addition, to make a reasonable conclusion from these photos, it would be important to know when they were taken. It might be possible that just after the impact the area wasnt very hot, but as the fire took hold the area got hotter.

The way the building collapsed must have been caused by explosions
One demolition expert on the day of the collapse said it looked like implosion but this is not very strong evidence. Implosion firstly requires a lot of explosives placed in strategic areas all around the building. When and how was this explosive placed in the building without anyone knowing about it. Second, implosion required more than just explosives. Demolition experts spend weeks inside a derelict building planning an event. Many of the beams are cut through by about 90% so that the explosion only has to break a small bit of steel. In this state the building is highly dangerous, and there is no way such a prepared building could still be running day to day like WTC was.

Why did the building fall so quickly?
The buildings did fall quickly - almost (but not exactly) at the same speed as if there was no resistance. Shouldn't the floors below have slowed it down? The huge dynamic loads due to the very large momentum of the upper floors falling were so great that they smashed through the lower floors very quickly. The columns were not designed to carry these huge loads and they provided little resistance.

What about World Trade Center 7?
I have not studied WTC in any great detail and cannot offer any theories on its collapse mechanism. In the chaos of the day, little attention was paid to WTC7, so there is less evidence available on the damage it sustained before it collapsed. However, some questions that you may want to ponder ...
* While it did not receive any direct impact form the planes, how much debris hit at as the main towers collapsed and what damage did it cause?
* To what extent (if any) did the shock or vibrations caused by the collapse of WTC1 & 2 affect the integrity of WTC7?
* Did any unseen damage to the WTC7 foundations occur in the collapse of WTC 1 & 2?
* Did any of the fire suppression systems in WTC7 function?


The author respect people's right to question theories, but at the present time the author does not believe there is enough evidence for him to change his views on this incident.

Why Did the World Trade Center Collapse?

There have been numerous reports detailing the cause of the World Trade Center Tower collapse on September 11, 2001. Most have provided qualitative explanations; however, simple quantitative analyses show that some common conclusions are incorrect; for example, the steel could not melt in these flames and there was more structural damage than merely softening of the steel at elevated temperatures. Some guidelines for improvements in future structures are presented.

INTRODUCTION

The collapse of the World Trade Center (WTC) towers on September 11, 2001, was as sudden as it was dramatic; the complete destruction of such massive buildings shocked nearly everyone. Immediately afterward and even today, there is widespread speculation that the buildings were structurally deficient, that the steel columns melted, or that the fire suppression equipment failed to operate. In order to separate the fact from the fiction, we have attempted to quantify various details of the collapse.

The major events include the following:
  • The airplane impact with damage to the columns.
  • The ensuing fire with loss of steel strength and distortion (Figure 1).
  • The collapse, which generally occurred inward without significant tipping (Figure 2).
Each will be discussed separately, but initially it is useful to review the overall design of the towers.

THE DESIGN

The towers were designed and built in the mid-1960s through the early 1970s. They represented a new approach to skyscrapers in that they were to be very lightweight and involved modular construction methods in order to accelerate the schedule and to reduce the costs.

To a structural engineer, a skyscraper is modeled as a large cantilever vertical column. Each tower was 64 m square, standing 411 m above street level and 21 m below grade. This produces a height-to-width ratio of 6.8. The total weight of the structure was roughly 500,000 t, but wind load, rather than the gravity load, dominated the design. The building is a huge sail that must resist a 225 km/h hurricane. It was designed to resist a wind load of 2 kPa—a total of lateral load of 5,000 t.

In order to make each tower capable of withstanding this wind load, the architects selected a lightweight “perimeter tube” design consisting of 244 exterior columns of 36 cm square steel box section on 100 cm centers (see Figure 3). This permitted windows more than one-half meter wide. Inside this outer tube there was a 27 m × 40 m core, which was designed to support the weight of the tower. It also housed the elevators, the stairwells, and the mechanical risers and utilities. Web joists 80 cm tall connected the core to the perimeter at each story. Concrete slabs were poured over these joists to form the floors. In essence, the building is an egg-crate construction that is about 95 percent air, explaining why the rubble after the collapse was only a few stories high.

Figure 1

Figure 1. Flames and debris exploded from the World Trade Center south tower immediately after the airplane’s impact. The black smoke indicates a fuel-rich fire (Getty Images).

Figure 2

Figure 2. As the heat of the fire intensified, the joints on the most severely burned floors gave way, causing the perimeter wall columns to bow outward and the floors above them to fall. The buildings collapsed within ten seconds, hitting bottom with an estimated speed of 200 km/h (Getty Images).

The egg-crate construction made a redundant structure (i.e., if one or two columns were lost, the loads would shift into adjacent columns and the building would remain standing). Prior to the World Trade Center with its lightweight perimeter tube design, most tall buildings contained huge columns on 5 m centers and contained massive amounts of masonry carrying some of the structural load. The WTC was primarily a lightweight steel structure; however, its 244 perimeter columns made it “one of the most redundant and one of the most resilient” skyscrapers.1

THE AIRLINE IMPACT

The early news reports noted how well the towers withstood the initial impact of the aircraft; however, when one recognizes that the buildings had more than 1,000 times the mass of the aircraft and had been designed to resist steady wind loads of 30 times the weight of the aircraft, this ability to withstand the initial impact is hardly surprising. Furthermore, since there was no significant wind on September 11, the outer perimeter columns were only stressed before the impact to around 1/3 of their 200 MPa design allowable.

The only individual metal component of the aircraft that is comparable in strength to the box perimeter columns of the WTC is the keel beam at the bottom of the aircraft fuselage. While the aircraft impact undoubtedly destroyed several columns in the WTC perimeter wall, the number of columns lost on the initial impact was not large and the loads were shifted to remaining columns in this highly redundant structure. Of equal or even greater significance during this initial impact was the explosion when 90,000 L gallons of jet fuel, comprising nearly 1/3 of the aircraft’s weight, ignited. The ensuing fire was clearly the principal cause of the collapse (Figure 4).

THE FIRE

The fire is the most misunderstood part of the WTC collapse. Even today, the media report (and many scientists believe) that the steel melted. It is argued that the jet fuel burns very hot, especially with so much fuel present. This is not true.

Part of the problem is that people (including engineers) often confuse temperature and heat. While they are related, they are not the same. Thermodynamically, the heat contained in a material is related to the temperature through the heat capacity and the density (or mass). Temperature is defined as an intensive property, meaning that it does not vary with the quantity of material, while the heat is an extensive property, which does vary with the amount of material. One way to distinguish the two is to note that if a second log is added to the fireplace, the temperature does not double; it stays roughly the same, but the size of the fire or the length of time the fire burns, or a combination of the two, doubles. Thus, the fact that there were 90,000 L of jet fuel on a few floors of the WTC does not mean that this was an unusually hot fire. The temperature of the fire at the WTC was not unusual, and it was most definitely not capable of melting steel.

In combustion science, there are three basic types of flames, namely, a jet burner, a pre-mixed flame, and a diffuse flame. A jet burner generally involves mixing the fuel and the oxidant in nearly stoichiometric proportions and igniting the mixture in a constant-volume chamber. Since the combustion products cannot expand in the constant-volume chamber, they exit the chamber as a very high velocity, fully combusted, jet. This is what occurs in a jet engine, and this is the flame type that generates the most intense heat.

In a pre-mixed flame, the same nearly stoichiometric mixture is ignited as it exits a nozzle, under constant pressure conditions. It does not attain the flame velocities of a jet burner. An oxyacetylene torch or a Bunsen burner is a pre-mixed flame.

In a diffuse flame, the fuel and the oxidant are not mixed before ignition, but flow together in an uncontrolled manner and combust when the fuel/oxidant ratios reach values within the flammable range. A fireplace flame is a diffuse flame burning in air, as was the WTC fire.

Diffuse flames generate the lowest heat intensities of the three flame types.

If the fuel and the oxidant start at ambient temperature, a maximum flame temperature can be defined. For carbon burning in pure oxygen, the maximum is 3,200°C; for hydrogen it is 2,750°C. Thus, for virtually any hydrocarbons, the maximum flame temperature, starting at ambient temperature and using pure oxygen, is approximately 3,000°C.

This maximum flame temperature is reduced by two-thirds if air is used rather than pure oxygen. The reason is that every molecule of oxygen releases the heat of formation of a molecule of carbon monoxide and a molecule of water. If pure oxygen is used, this heat only needs to heat two molecules (carbon monoxide and water), while with air, these two molecules must be heated plus four molecules of nitrogen. Thus, burning hydrocarbons in air produces only one-third the temperature increase as burning in pure oxygen because three times as many molecules must be heated when air is used. The maximum flame temperature increase for burning hydrocarbons (jet fuel) in air is, thus, about 1,000°C—hardly sufficient to melt steel at 1,500°C. 

Figure 3

Figure 3. A cutaway view of WTC structure.

Figure 4--Web Link

Figure 4. A graphic illustration, from the USA Today newspaper web site, of the World Trade Center points of impact. Click on the image above to access the actualUSA Today feature.

But it is very difficult to reach this maximum temperature with a diffuse flame. There is nothing to ensure that the fuel and air in a diffuse flame are mixed in the best ratio. Typically, diffuse flames are fuel rich, meaning that the excess fuel molecules, which are unburned, must also be heated. It is known that most diffuse fires are fuel rich because blowing on a campfire or using a blacksmith’s bellows increases the rate of combustion by adding more oxygen. This fuel-rich diffuse flame can drop the temperature by up to a factor of two again. This is why the temperatures in a residential fire are usually in the 500°C to 650°C range.2,3 It is known that the WTC fire was a fuel-rich, diffuse flame as evidenced by the copious black smoke. Soot is generated by incompletely burned fuel; hence, the WTC fire was fuel rich—hardly surprising with 90,000 L of jet fuel available. Factors such as flame volume and quantity of soot decrease the radiative heat loss in the fire, moving the temperature closer to the maximum of 1,000°C. However, it is highly unlikely that the steel at the WTC experienced temperatures above the 750–800°C range. All reports that the steel melted at 1,500°C are using imprecise terminology at best.

Some reports suggest that the aluminum from the aircraft ignited, creating very high temperatures. While it is possible to ignite aluminum under special conditions, such conditions are not commonly attained in a hydrocarbon-based diffuse flame. In addition, the flame would be white hot, like a giant sparkler. There was no evidence of such aluminum ignition, which would have been visible even through the dense soot.

It is known that structural steel begins to soften around 425°C and loses about half of its strength at 650°C.4 This is why steel is stress relieved in this temperature range. But even a 50% loss of strength is still insufficient, by itself, to explain the WTC collapse. It was noted above that the wind load controlled the design allowables. The WTC, on this low-wind day, was likely not stressed more than a third of the design allowable, which is roughly one-fifth of the yield strength of the steel. Even with its strength halved, the steel could still support two to three times the stresses imposed by a 650°C fire.

The additional problem was distortion of the steel in the fire. The temperature of the fire was not uniform everywhere, and the temperature on the outside of the box columns was clearly lower than on the side facing the fire. The temperature along the 18 m long joists was certainly not uniform. Given the thermal expansion of steel, a 150°C temperature difference from one location to another will produce yield-level residual stresses. This produced distortions in the slender structural steel, which resulted in buckling failures. Thus, the failure of the steel was due to two factors: loss of strength due to the temperature of the fire, and loss of structural integrity due to distortion of the steel from the non-uniform temperatures in the fire.

THE COLLAPSE

Nearly every large building has a redundant design that allows for loss of one primary structural member, such as a column. However, when multiple members fail, the shifting loads eventually overstress the adjacent members and the collapse occurs like a row of dominoes falling down.

The perimeter tube design of the WTC was highly redundant. It survived the loss of several exterior columns due to aircraft impact, but the ensuing fire led to other steel failures. Many structural engineers believe that the weak points—the limiting factors on design allowables—were the angle clips that held the floor joists between the columns on the perimeter wall and the core structure (see Figure 5). With a 700 Pa floor design allowable, each floor should have been able to support approximately 1,300 t beyond its own weight. The total weight of each tower was about 500,000 t.

As the joists on one or two of the most heavily burned floors gave way and the outer box columns began to bow outward, the floors above them also fell. The floor below (with its 1,300 t design capacity) could not support the roughly 45,000 t of ten floors (or more) above crashing down on these angle clips. This started the domino effect that caused the buildings to collapse within ten seconds, hitting bottom with an estimated speed of 200 km per hour. If it had been free fall, with no restraint, the collapse would have only taken eight seconds and would have impacted at 300 km/h.1 It has been suggested that it was fortunate that the WTC did not tip over onto other buildings surrounding the area. There are several points that should be made. First, the building is not solid; it is 95 percent air and, hence, can implode onto itself. Second, there is no lateral load, even the impact of a speeding aircraft, which is sufficient to move the center of gravity one hundred feet to the side such that it is not within the base footprint of the structure. Third, given the near free-fall collapse, there was insufficient time for portions to attain significant lateral velocity. To summarize all of these points, a 500,000 t structure has too much inertia to fall in any direction other than nearly straight down.

Figure 5

Figure 5. Unscaled schematic of WTC floor joints and attachment to columns.

WAS THE WTC DEFECTIVELY DESIGNED?

The World Trade Center was not defectively designed. No designer of the WTC anticipated, nor should have anticipated, a 90,000 L Molotov cocktail on one of the building floors. Skyscrapers are designed to support themselves for three hours in a fire even if the sprinkler system fails to operate. This time should be long enough to evacuate the occupants. The WTC towers lasted for one to two hours—less than the design life, but only because the fire fuel load was so large. No normal office fires would fill 4,000 square meters of floor space in the seconds in which the WTC fire developed. Usually, the fire would take up to an hour to spread so uniformly across the width and breadth of the building. This was a very large and rapidly progressing fire (very high heat but not unusually high temperature). Further information about the design of the WTC can be found on the World Wide Web.5–8

WHERE DO WE GO FROM HERE

The clean-up of the World Trade Center will take many months. After all, 1,000,000 t of rubble will require 20,000 to 30,000 truckloads to haul away the material. The asbestos fire insulation makes the task hazardous for those working nearby. Interestingly, the approximately 300,000 t of steel is fully recyclable and represents only one day’s production of the U.S. steel industry. Separation of the stone and concrete is a common matter for modern steel shredders. The land-filling of 700,000 t of concrete and stone rubble is more problematic. However, the volume is equivalent to six football fields, 6–9 m deep, so it is manageable.

There will undoubtedly be a number of changes in the building codes as a result of the WTC catastrophe. For example, emergency communication systems need to be upgraded to speed up the notice for evacuation and the safest paths of egress. Emergency illumination systems, separate from the normal building lighting, are already on the drawing boards as a result of lessons learned from the WTC bombing in 1993. There will certainly be better fire protection of structural members. Protection from smoke inhalation, energy-absorbing materials, and redundant means of egress will all be considered.

A basic engineering assessment of the design of the World Trade Center dispels many of the myths about its collapse. First, the perimeter tube design of the towers protected them from failing upon impact. The outer columns were engineered to stiffen the towers in heavy wind, and they protected the inner core, which held the gravity load. Removal of some of the outer columns alone could not bring the building down. Furthermore, because of the stiffness of the perimeter design, it was impossible for the aircraft impact to topple the building.

However, the building was not able to withstand the intense heat of the jet fuel fire. While it was impossible for the fuel-rich, diffuse-flame fire to burn at a temperature high enough to melt the steel, its quick ignition and intense heat caused the steel to lose at least half its strength and to deform, causing buckling or crippling. This weakening and deformation caused a few floors to fall, while the weight of the stories above them crushed the floors below, initiating a domino collapse.

It would be impractical to design buildings to withstand the fuel load induced by a burning commercial airliner. Instead of saving the building, engineers and officials should focus on saving the lives of those inside by designing better safety and evacuation systems.

As scientists and engineers, we must not succumb to speculative thinking when a tragedy such as this occurs. Quantitative reasoning can help sort fact from fiction, and can help us learn from this unfortunate disaster. As Lord Kelvin said,
“I often say . . . that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be.”
We will move forward from the WTC tragedy and we will engineer better and safer buildings in the future based, in part, on the lessons learned at the WTC. The reason the WTC collapse stirs our emotions so deeply is because it was an intentional attack on innocent people. It is easier to accept natural or unintentional tragedies; it is the intentional loss of life that makes us fear that some people have lost their humanity.

Nintendo 3DS

Nintendo has announced the release dates of its forthcoming 3D handheld gaming console at joint press event in New York and Amsterdam.
The Nintendo 3DS will be released in the U.S. on March 27th priced at $249.99, but will hit the stores a few days earlier in Europe on the 25th, at a price decided by retailers (hmmm?). Joystick and other retailers have the device priced at 229.99 pounds in the UK, and 249.99 Euros elsewhere.
nintendo 3ds march release
Nintendo 3DS Set For March Release
Like the original DS, the 3DS includes two screens – the bottom touch screen making use of the included telescoping stylus.
However this time Nintendo has included 3 cameras; one front-facing and two at the rear to take 3D photos. The intensity of the 3D video and images can be increased or decreased to suit the user’s preference using the Depth Slider.
Nintendo has promised 30 games for the U.S. and 25 for Europe between the release date and the end of June this year. Many games were features in the press conference however we don’t have any dates for specific titles just yet. Games should run around 40-50 dollars a piece.
European users will be treated exclusive 3D content from the likes of Eurosport, episodes of Shaun the Sheep, a new series from Wallace & Gromit creators Aardman, will be available as well.
No word on exclusive content for America at the mo’, however Nintendo said they are working with particular countries to strike specific deals; in the UK Nintendo has partnered with British Sky Broadcasting, so it’s likely that deals in other countries are to follow soon enough.Here’s a list of forthcoming titles we can expect to see for the 3DS.
  • The Legend of Zelda: Ocarina of Time 3D
  • Star Fox 64 3D
  • Kid Icarus: Uprising
  • Mario Kart
  • Animal Crossing
  • Paper Mario
  • Pilotwings Resort
  • Wuhu Island; nintendogs + cats
  • Steel Diver
  • Resident Evil: The Mercenaries 3D Edition from Capcom
  • The Sims 3
  • Madden NFL Football from Electronic Arts
  • PES 2011 3D – Pro Evolution Soccer from Konami
  • LEGO Star Wars III The Clone Wars from LucasArts
  • Ridge Racer 3D from Namco Bandai
  • Super Monkey Ball 3D
  • Crush 3D
  • Thor : God of Thunder, from SEGA
  • Puzzle Bobble Universe from Square Enix, Co., Ltd
  • Samurai Warriors: Chronicles
  • DEAD OR ALIVE Dimensions from Tecmo Koei.Europe Ltd
  • Tom Clancy’s Ghost Recon Shadow Wars
  • Tom Clancy’s Splinter Cell 3D
  • Rayman 3D
  • Asphalt 3D
  • Combat of Giants
  • Dinosaurs 3D
  • James Noir’s Hollywood Crimes
  • Driver
  • Renegade and Rabbids 3D from Ubisoft

Iphone 4G..

So it’s finally here. After all the hype, creative PR (mistake my a**), and law suits that have become entwined to the saga, it didn’t come as much of a surprise to see Steve Jobs unveil Apples new iPhone 4G at the WWDC Keynote, June 7th.
So what does the new iPhone – set for release 24th June – have in store for its users? First off, the device runs on the more powerful,more efficient A4 processor also found in the iPad. The graphics are powered by an HD capable PowerVR SGX 535; and two low power 128MB [update:] 512MB DDR SDRAM make up the system memory.
iPhone 4G
iPhone 4G
Apple claims the new iPhone 4G is the thinnest smart phone in the world – its 34% thinner than the iPhone 3GS – and since all the components are neatly packed together on the same chip, the phone can , apparently, process data quicker while still consuming less battery than previous versions. Interestingly enough, the battery is actually 16% larger than before and Apple claims it will provide up to:
  • 7 hours talking over 3G
  • 6 hours browsing over 3G
  • 10 hours browsing over Wi-Fi
  • 10 hours playing video
  • 40 hours playing music
  • 300 hours standby
Other key features include:
  • 3.5 inch multitouch screen with a 960 x 640 pix resolution.
  • 720p High Definition video.
  • Retina Display with 326 pixel per inch resolution, higher definition than a magazine and four times as many pixels as the current iPhone 3GS’ display.
  • The display also has an oleophobic layer making it easier to clean.
  • ISP-based technology – used in the iPad – with 800: 1 contrast ratio.
  • Wider viewing angle.
  • Front and rear built-in camera.
  • 5 Megapixel rear-facing (main) camera with a larger sensor.
  • Higher ISO for better lowlight shots.
  • LED-based flash, which works both for photographs and video.
  • New 3- axis gyroscope coupled with the accelerometer provides 6-axis motion sensing.
  • Micro-SIM.
  • Additional microphone used for noise cancellation.
  • i OS 4 operating system with multi-tasking.
Aside from the upgraded internal components, iPhone fans will be pleased to note the addition of 2 great new features; video calling; and multi-tasking.
Perhaps the biggest new feature of the iPhone 4F is video calling. Thanks to the front facing camera – and Apples FaceTime or 3rd party software – your video calling recipients will now not only be able to see you, but will also have to option to see the rear camera view so you can share what you’re seeing at the time. The video calling feature currently only works over a Wi-fi network, however Apply says it will be 3G compatible soon by next year.
FaceTime Video Calling
FaceTime Video Calling
The phones’ new ability to multitask should also prove very useful. Finally users should be able to check emails while still listening to Pandora, or keep playing that fav’ video on YouTube whilst quickly adding a note to your calendar.
The Phone 4 is will be available in black or white, from June 24, and will cost $199 and $299 for 16 and 32GB if you are a new user or you are eligible for an upgrade.

More information CLICK HERE

China’s new J-20 stealth fighter takes to the skies ahead of schedule...


Around the turn of the New Year grainy mobile-phone photos of what appeared to be China’s new J-20 stealth fighter taxiing along the runway in Chenghdu started to emerge on the web.
Skeptics were quick to pick faults with the images and claimed they were fake, however two weeks later, China’s President, Mr. Hu Jintao, confirmed to U.S. Defense Secretary Robert Gates that the J-20 had begun its testing phase and successfully made its first test flight on January the 10th.
china j-20 stealth fighter
China's J-20 Stealth Fighter
The BBC quoted Mr. Hu saying that the test flight was not timed to coincide with Gates visit, as many had expected.
The test flight lasted around 15 minutes from take-off to landing. As Defense Blog Ares writer Robert Wall points out, it appears that the landing remained extended throughout the flight – however it is a little difficult to tell from the quality of the video clip.


Currently, the U.S. is the only country with a fully operational stealth fighter in its arsenal; however both Russia and China are working to develop their own fighter that is invisible to radar.
j-20 stealth fighter first test flight
J-20 Stealth Fighter Makes First Test Flight
The images and video of the J-20 making its test flight ahead of schedule had raised concerns that China could be ready to add a high-tech strike-fighter to its forces quicker than anticipated.
However, as U.S. director of naval intelligence Vice Admiral David Dorsett, pointed out to the BBC, “Developing a stealth capability with a prototype and then integrating that into a combat environment is going to take some time,” [BBC]
Nevertheless, China expects the stealth plane to be operational sometime between 2017 and 2019.
Ares Defense Blog writer Bill Sweetman followed up with some interesting technical analysis of the J-20 – based on what can be seen in the pics – offering several possibilities as to the mission objectives and performance abilities of the J-20

The X-47B makes its first flight…


Northrop Grumman’s X-47B unmanned combat air system (UCAS-D) successfully made its first test flight, 04th February, 2011, over Edwards Air Force Base, California.
The single engine combat UAV took off at 2.09pm PST at a speed of 180kt, and flew in a figure of 8 pattern for duration of 29 minutes. During the test flight the X-47B reached an altitude of 5,000 ft and a maximum speed of 240kts.
x-47b unmanned combat air system first flight
X-47B UCAS First Test Flight
The first X-47B, aircraft 1 or AV1, made its test flight with the landing gear down and while there were no hiccups during the flight, it did land 60ft ahead of where it was expected to. Although the craft overshot its landing it did land directly in the centerline, which gives the team a good starting point from which to tweak the flight control system.


The X-47B was originally scheduled to fly before the end of December, but braking issues further held up the already delayed test flight. Another last minute problem with the auxiliary power generation system stopped the craft from flying on Thursday, but the team was quick to make the necessary adjustments to ready the AV1 for the following day.
The second aircraft, the AV2, also completed it tests – to asses if the airframe could handle the 2.4g loads it may experience during air-to-air refueling – with ‘no test anomalies.’ The AV2 is now being prepared for fuel testing before being transferred to Edwards AFB in March with the goal of making its first flight in August.
Later in the year AV-1 will be transferred to the NAS Patuxent River, Md, Navy test center, where it will undergo tests onboard an aircraft carrier.

AirMule VTOL UAV.........coolllll

Israel’s Urban Aeronautics is currently developing a hover capable, VTOL drone primarily designed for medevac and cargo missions.
The AirMule is a specialized UAV concept first unveiled back in 2008, but earlier this month the aircraft made it’s first successful (but tethered) liftoff.
AirMule VTOL UAV
AirMule VTOL UAV
The AirMule is powered by a 730shp Turbomeca Arriel I turboshaft driving fore and aft ducted rotors. Although the craft didn’t necessarily make it’s maiden flight, it did demonstrate the control system’s ability to stabilize the vehicle in all three axes using inertial measurements augmented by GPS and two laser altimeters.
The company hopes that planned improvements will allow the production vehicle to hover with high precision in winds gusting up to 50kt.
The next phase of flight tests will be untethered and will include horizontal and vertical position stabilization.
AirMule UAV Concept
AirMule UAV Concept
The VTOL engines will allow the AirMule to navigate in and out of compact alleyways and refugee camp warrens, while the shielded rotor blades protect make it tougher than a regular helicopter. An because it’s unmanned , the craft can enter situations too risky for regular helicopters.
Urban Aeronautics is developing the AirMule for the Israeli army, who have already expressed an interest in the unmanned robotic ambulance.