Brazuca: Even NASA tested the ball of Brasil 2014 world cup.

World cup just began and all the world turn around the Brazuca, the official of the 2014 FIFA world cup. The ball is manufactured in Pakistan by the sport label ADIDAS.

Besides it 69 cm circumference and it 437 grams, what is special about Brazuca compared to other balls?

Unique aerodynamic
There is some controversy about the effect of wind on the game. Especially the Jabulani ball (2010 world cup) was severely criticized about its aerodynamics and its erratic movement. ADIDAS states that aerodynamic problems will not be present in the Brazuca due to its six identical locking patches that makes it the most spheric ball. The previous Jabulani had eight non-identical patches and the classic balls have 32 hexagonal patches.

Even scientists from NASA had tested the aerodynamics of the Brazuca. NASA tested the Brazuca through a wind tunnel and analyzed its aerodynamics at different speeds.

The roughness of the material and the 6 thermally bonded locking patches increase the seam length; such characteristic along with the roughness of the micro-textured surface improved the aerodynamics and eliminates the erratic movement of Jubulani. Its will produce faster speed and maintain the shape and weight of the ball.

Video 1. NASA tested the aerodynamics of Brazuca
Source: Bloomberg

Why Brazuca?
The name Brazuca was selected by a public vote conducted on line in 2012. It is an informal description of the Brazilian way of life. The other names considered in the vote were Bossa Nova (A very famous genre of Brazilian music) and Carnavalesca (due to the fame of the Brazilian carnival).

The colours and ribbon design of the ball panels symbolize the traditional multi-coloured wish bracelets (fita do Senhor do Bonfirm da Bahia) worn in the country, in addition to reflecting the vibrancy and fun associated with football in Brazil.

Image. Brazuca ball

References & further reading
ADIDAS brazuca, tried and tested
Brazil ready for made in Pakistan Brazuca ballas
Testing the world cup ball in a NASA wind tunnel
Feet on with ADIDAS brazuca

Body fat estimation using bioelectrical impedance

I like excersice and I like fitness. Many times I have comments from friends about the body fat and I also found many people misusing the Bioelectrical Impedance Analysis (BIA). Actually some people don't even know what the BIA is and still use it.

bio electrical impedance for fitness
Image 1. Person using a BIA
Image source: Excercisebiology

BIA and body fat estimation

The BIA is a widely used method for estimating body composition, especially the body fat. Despite the general idea that BIA gives you the body, it does not measure the body fat.

The BIA determines the electrical impedance of body tissues (opposition of a conductor to the flow of an alternating current), which provides an estimate of the total body water (TBW).

The impedance measured by BIA allows to estimate the body fat (BF), the fat free mass (FFM) and the body cell mass. Several studies analyzed suggested empirical equations developed by analyzing the physical characteristic of different populations; hence, they have different predictive accuracy.

fitness equations
Image 2. Comparison of predictive accuracy of different equations for estimating BF
Image source: Kao et al., 2010

Some suggestions before using BIA

Some suggestions about the use of BIA for estimating your body fat.
  • Firm holding with of the BIA device. BIA will not provide the real body fat, but it does provide a reasonable guide. BIA does not provide the exact body fat, but it will indicate in you maintain a stable body fat, or if you tend to increase or reduce your body fat.
  • Use the BIA at the same time. Our metabolism changes during the day. Impedance when we wake up is different than the impedance at noon of at night.
  • Do not eat before BIA. Food intake, its absorption and the resulting increase in movement of fluid into the bloodstream from 2–4 hours before BIA measurement, decreases the impedance value and underestimates the body fat.
  • Use BIA before exercising. Moderate exercise before using the BIA decrease the impedance and will underestimate the body fat. Underestimation due to exercise is twice the one due to eating.
  • Use BIA under the same environmental conditions. Different environmental conditions may change the skin temperature and lead to different impedance.

Refernces & Further Reading
Bioelectrical impedance analysis in body composition measurement
Comparisson of different measurement equations for body composition estimation in male athletes

Moving a 122.5 m Arch bridge in 7 hours

Bridges are structures built to span physical obstacles, in order to provide a direct passage throughout such obstacle. Some time ago the U.S. navy faced the need to build a bridge in order to connect its existing base in Manama - Bahrain with new expansion properties located on the other side of the Sheikh Khalifa bin Salman Causeway. Initially this seems an ordinary building task; however, an in situ building would have meant to interrupt the causeway and nearby traffic for several days. Thus, it was decided to build the bridge at other location and then move it into place.

Image 1. Construction of the arch bridge over the Sheikh Khalifa bin Salman Causeway
Source: USACE

Moving the bridge

The bridge is a tied up bridge with a total length of 122.5 m and 10.6 m wide.

The bridge has a total high of 21.4 m and a total weight of more than 2650 metric ton.

Image 2. Arch bridge over the Sheikh Khalifa bin Salman Causeway
Source: ASCE

Initially the Army Corps planned to close the causeway some 48 hours in order to allow enough time to prepare the road for the move by removing the curb and median and then subsequently moving the bridge into place. However, Bahrain authorities said that the closure time should be limited to 7 hours.

In order to move the massive bridge, self propelled mobile transports were used. These machines, two twelve axle units on each corner, lifted the bridge at its bearing points and safely moved it onto pre-constructed abutments.
Image 3. Self propelled mobile transport used.
Source: USACE
Before the move, support beams were installed at each end and the bridge was suspended from the beams using two-inch diameter high-strength rods, eight at each end. In addition to the support beam installation, a roadway analysis was completed on the causeway to ensure that the pavement could withstand the weight of the bridge, which weighed more than 3,000 metric ton once the beams were installed. During the move, each pair of mobile transports at opposite ends of the bridge were manually controlled and each set of wheels, 48 sets on each transport, could be adjusted and turned individually. This had to be done before each segment of the move.

 One of the greatest concerns for engineers was to not place a lot of stress on the bridge. In order to monitor stress levels, engineers used both hi-tech and lo-tech methods. They monitored tire pressure of each wheel using computerized sensors. Engineers also attached laser pointers to one end of the bridge on each side and four-inch diameter targets to the other end. They did the same across the width of the bridge on each end as well.

References & Further reading
Bahrain bridge a first of Army Corps of Engineers
Bahrain bridge move huge engineering feat

Chinese Qihoo360, best antivirus

This post is from 2014. You can check the updated post with the best antivirus for 2019

Computer virus are software that when executed in a given computer (affected area) perform some type of harmful activity. There is a wide range of computer virus with different definitions (malware, trojan, bugs, spyware, and more) according to the way they infect and the harm they produce. Thus, antivirus software was created in order to prevent, detect and remove computer virus.

We have a wide availability of different computer antivirus software, both free and with a given economic license costs. We always have the doubt of which antivirus is the best one. Of course everyone has its own preferences according to its personal needs. Nevertheless, different institutions perform tests on different antivirus available in order to provide guides about their performance. Due to the high dynamic of the IT world, such comparisons are continuously performed and every two months they provide new results and rankings.

In the most recent rank (January-February 2014) from AV-TEST, the Chinese antivirus Qihoo360 got the highest qualification.

computer virus maleware

Image 1. Computer virus
Source: Dreamstime

The comparison

The common procedure of comparing antivirus products consists on comparing the performance considering 4 categories (it used to be 3 categories, but one new category was recently included):

Protection. This is performed by installing the product into a non-infected system and then evaluate how they respond to different threats.

Performance. This category consists on evaluation the influence of the product on the system speed. For instance, some tasks (like files downloading, copying files, running and executing common products like Microsoft Word or Microsoft Excel) may become little slower or very much slower.

Usability. This category investigates the influence that the security software has on the usability of the system and any system interference that may occur. For example, warning messages and warning pop ups that may be annoying and difficult to remove. Other example in this category are the false reports, which is very common when plugging USB data device or introducing a CD; usually the auto-executable of such devices is considered a threat, preventing the execution of the desired file.

Repair. This new category evaluates the products ability to remove virus and to restore files or system changes affected by the virus. This is a new category, and was not yet evaluated in the last report (February 2014).

best antivirus
Image 2. Wigoo user interface
Soure: ZDNet


Qihoo360 technology CO. Ltd. is an internet platform company from China. It is one of the top three internet companies from China, the number one provider of internet and mobile security products and services in China and the number 2 internet browsers from China. Considering the Chinese market and the aproximatly 441 million of monthly active users from this company, it may also be one of the biggest in the world.

In the last comparisson report, Qihoo 360 earned a total of 17.5 points (the maximum possible is 18; 6 point for each category). 6 points for protection, 6 points for usability and 5.5 points for performance.

The other day I just found an article suggesting that the Chinese city of Shenzhen is becoming the new Silicon valley (location of the most important high technology companies). Although this is another topic, this results (Chinese antivirus ranked as number one) along with the growing experienced by China in other fields surely shows that market and the IT industry is moving towards East.

antivirus 360 china
Image 3. Qihoo logo image
Soirce: ZDNet

References & Further reading
Chinese antivirus Qihoo 360 earns top score in independent test
Is Shenzhen the new Silicon valley

IPCC AR5, the representative concentration pathways

One of the most important events expected for this 2014 is the official release of the Intergovernmental Panel on Climate Change (IPCC) fifth assessment report (AR5). The IPCC began working on the AR5 in 2010. Between 2011 and 2013 some drafts were published on the internet. In September 2013 the working group 1 (The physical science basis) completed its report.The working group 2 (Impacts, adaptation and vulnerability) and the working group 3 (Mitigation of climate change) are expected to finish this year aloing with the nfinal synthesis report. but by this years it is expected that the final official version to be released.
Up to the last year we used to talk about the Special Report on Emissions Scenarios (SRES), but the AR5 uses a new term: Representative Concentration Pathway (RCP).
AR5 relies on the Coupled Model Intercomparison Project Phase 5 (CMIP5), an international effort among the climate modeling community to coordinate climate change experiments. Most of the CMIP5 and Earth System Model (ESM) simulations for AR5 were performed with prescribed CO2 concentrations reaching 421 ppm (RCP2.6), 538 ppm (RCP4.5), 670 ppm (RCP6.0), and 936 ppm (RCP 8.5) by the year 2100. (

Image 1. Cover of the IPCC-AR5

What is the RCP
They are prescribed pathways for greenhouse gas and aerosol concentrations, together with land use change, that are consistent with a set of broad climate outcomes used by the climate modelling community.
The pathways are characterised by the radiative forcing produced by the end of the 21st century. Radiative forcing is the extra heat the lower atmosphere will retain as a result of additional greenhouse gases, measured in Watts per square meter (W/m2).
Image 2. Temperature differences by the end of the 21st century
Source: Zeeburgnieuws

The RCPs span a wider range of possibilities than the SRES marker scenarios used in the modelling for the IPCC 3rd and 4th Assessment.
RCPs start with atmospheric concentrations of greenhouse gases rather than socioeconomic processes. This is important because every modelling step from a socioeconomic scenario to climate change impacts adds uncertainty. By starting with concentrations, there are fewer steps to impacts and therefore less cumulative uncertainty in impact assessments. This way uncertainty is shared more evenly among the various components. RCP also includes mitigation and adaptation policies. The figure shows a comparison of the CO2 projections according to SRES and RCP.
Image 3. Relation between RCO and SRES scenarios
Source: WMO

References & Further Reading
IPCC 5th assessment report
Representative concentration pathways

Boundary conditions in HEC RAS

The basic data needed to calculate hydraulic profiles of a channel are the discharge, the channel geometry, the water elevation at a control section and the channel roughness.

Discharge is a given data and the channel geometry is obtained by measurements. Usually the water elevation at control section (boundary condition) and channel roughness are unknown and have to be estimated by indirect ways.

Although there are different approaches and recommendations for defining the boundary conditions, they are just suggestions and incorporate an error to the vicinity of the boundary station and cross sections.

The best approach is to perform a sensitivity analysis of the boundary condition, and if needed to perform an uncertainty analysis. Although the task of updating either the boundary condition or manning roughness are simple ones, when repeating many times (sensitivity and uncertainty analysis) it may become a tedious and time consuming task; besides, the possibility of accidental errors when typing values increase.

Boundary conditions in HEC-RAS

A boundary condition defines the starting water level at the end of the river, which is needed so that the program can begin the calculations. HEC-RAS allows specifying boundary condition in one of the following options:

  • Known water surface: This is the known water surface for the given profile. This option applies for cases where the water level was measured for a given discharge.
  • Critical depth: With this option the program calculates the critical depth for the section and uses it as boundary condition. This option applies for cases where there is a control structure such as weir, gate or drop that controls and forces the critical depth.
  • Rating Curve: In this option the water level is interpolated from the given rating curve. Usually this case applies for control station where water levels and discharges are measured constantly.
  • Normal depth: In this option the program uses the energy slope to calculate the normal depth with Manning's equation.
The most used boundary condition is the normal depth. Although the normal depth is unknown, usually it is approximated either by using the channel slope or the water surface slope near the boundary station. Nevertheless, these are just approximations that incorporates an error to the vicinity of the boundary station; thus, is suggested to increase the cross sections and channel length (which increases the topographical data required) so that these errors do not affect the study area.

Figure 1 shows a river hydraulic profile under normal depth boundary condition located downstream. The hydraulic profile is from a river with a low topographic gradient around 0.0015 m/m. Different values of normal depth slope between 0.001 m/m and 0.015 m/m were tested. The uncertainties due to the boundary condition propagate some 1500 m upstream. The hydraulic profile in those 1500 m is strongly influenced by the selected slope.  
HEC-RAS boundary conditions uncertainty
Image 1. Influence of boundary conditions
Source: AHYDRA

The best approach is to perform a sensitivity analysis of the boundary conditions, and if needed to perform an uncertainty analysis. In the present case, if the study area is located more than 1500 m upstream, then the uncertainties of the boundary condition have minor influence. However, if the study area is within the first 1500 m, then it is important to analyze the different profiles. For instance, a visual analysis shows that the highest slope forces a higher velocity and lower depth at the boundary section; thus, the backwater shows a concave curve to fit the imposed condition. On the other side, the other slopes shows a backwater profile with the same pattern over the whole river length. 

Although the task of updating the boundary condition is a simple one, when repeating many times (sensitivity and uncertainty analysis) it may become a tedious and time consuming task. For such purpose, we developed the Automating Hydraulic Analysis (AHYDRA) tool. This software allows updating boundary condition, executing the simulation and viewing the results from a single screen and a single instruction (button click).

Automating Hydraulic Analysis in HEC-RAS AHYDRA

AHYDRA is a freeware application that can be downloaded from its website.

It comes in a compressed .rar file. Just decompress it in the path “C” so that it will create a folder with the path “C:\AHYDRA” and launch it by double clicking the AHYDRA.exe icon. Before executing it, be sure that you have HEC-RAS version 4.1 installed. If you have a previous version the AHYDRA will not work.

NOTE: It is important to have the “C:\AHYDRA” path in order to overcome accessibility limitations with the “C:” and “Program Files” folder.

The following video shows the use of AHYDRA for automating boundary conditions in HEC RAS.

Video 1. Automating boudary conditins in HEC RAS
Source: AHYDRA

References & Further reading
HEC-RAS evolution
HEC RAS hydraulic reference
Open Channel hydraulics
AHYDRA basic tutorial
Automating hydraulic analysis AHUDRA
Youtube tutorials

The Shanghai Tower: 2nd tallest skyscraper of the world

This year 2014 is the when when 2 of the highest skyscrapers in the world are expected to be inaugurated. The Shanghai Tower is the second tallest building in the world, and the New One World Trade Center (NOWTC) is the third tallest building in the world. We already made an introduction about the NOWTC, now is the time for the Shanghai Tower. 

China tallest skycreaper building
Image 1. Shanghai Tower with the Jin Mao Tower and SWFC

Some facts of the Shanghai Tower:
Height: 632 meters (2073 feet)
From base to top the building rotates 120 degree in order to minimize the wind loads. This geometry allowed the saving of nearly 58 million $ in structural materials.
The building adopts sustainbale technologies that reduced the energy consumption by 21%.
The building has an innovative circular inner-glass facade that requires 14% less glass than a square building of the same area.
In March 2010 several trucks pumped concrete during 63 continuous hours in oprder to complete the 6 meter (18 feet) deep foundation.
The energy will be supplied by a 2130 kW gas fired generator.
The express elevator has velocity of 40 mph (18 m/s). Such velocity makes convert those elevators in the fastest of the world.
When completed, the Shanghai Tower will join the Jin Mao Tower and SWFC to form the world's first adjacent grouping of three super-tall buildings.
The glass skin maximizes the daylight, reducing the use of electric lighting.

The tower takes the form of nine cylindrical buildings stacked atop each other. The tower has a total of 121 floors, all enclosed by the inner layer of the glass facade. Between that and the outer layer, which twists as it rises, nine indoor zones will provide public space for visitors. Each of these nine areas will have its own atrium, featuring gardens, cafes, restaurants and retail space and providing 360-degree views of the city

Due to its numerous green architecture elements incorporated, the Shanghai Tower will achieve both LEDD Gold certificate and the China Green Building Star rating. The design of the tower's glass facade is intended to reduce wind loads on the building by 24%. This reduces the amount of construction materials needed; the Shanghai tower used 25% less structural steel than a conventional design of a similar height. As a result, the building's constructors are expected to save an estimated US$58 million in material costs.

Though the majority of the tower's energy will be provided by conventional power systems, vertical-axis wind turbines located near the top of the tower will generate up to 350,000 kWh of supplementary electricity per year. The double-layered insulating glass facade is intended to reduce the need for indoor air conditioning, and is composed of an advanced reinforced glass with a high tolerance for shifts in temperature.

References & Further Reading
Shanghai Tower: Gensler design update
The Shanghai Tower: The Beginnings of a Green Revolution in China

Vinyl records to come back in 2014?

Most of the people born after 1990 have never played a vinyl record, maybe some people have not even hold a vinyl record. The digital era and its rapid advance and development have dominated the world of sounds and music.

The digital sounds have many clear advantages over the analogical sounds from vinyl records. The price reduction is a great advantage. The technology advances have reduced the production costs. Actually nowadays people don't even need to buy the music, just searching in websites like youtube or grooveshark and we can easily find a specific song.

However, the experience of holding and listening your favorite song in a vinyl record is something unique that will never be replaced by the digital world. The personal experience and the personal time quality of listening a vinyl record is different. To hold the record and watch the cover; those covers are art. Then put the record, blow some air to the needle and put the needle. Then, while the first sounds before the song you sit and open the record (or a book). It is true that you CDs, DVDs and Blue-rays also have an art cover together with lyrics and notes about the songs and album; you can also have the music on your computer device and print the cover or anything. However, it is not the same to watch a 30*30 cm image and the same image inside an 12*12 cm.

Image 1. Cover of the album Sgt. Pepper's Lonely Hearts Club Band
Image Source: Wikipedia

Another characteristic of vinyl records is the arrangement of the songs. When listening to a vinyl record you do not just listen to a song, but you listen to the whole album. Some people even state that listening to a vinyl record is like listening to a music book, the album has a name and the songs are arranged in such a way that follow tell a history according to the album title. Not only the order of the songs, but also which songs are one side on the record and which songs are in the other side.

The last 2013 showed an unexpected rise in the sales of vinyl records. The German company Optimal Media is trying to meet the demand, but one of its biggest problems is that nobody makes the required anymore. This unexpected sales increase shows that vinyl records are not only part of the so called retro-mania, but actually some bands like Daft Punk or Arctic Monkeys  released vinyl records albums during 2013. Will this 2014 will be the year when vinyl records come back? By come back I do not mean that they will be higher than the digital audio. Actually I think that digital music will never be overcame by analogical music, but the truth is that vinyl records are not death and they will never be.

Video 1. BBC report. Are vinyl records making a comeback

References & Further Reading
Are vinyl records making a comeback
Vinyl sales at highest level for more than a decade