Wall-Climbing Concrete-Evaluation Robot Successfully Tested

A new robot for inspection of concrete successfully climbed the dam’s walls, testing the dam’s structural reliability.

Numerous of the America’s 104 nuclear plants are crossing the mid age of their deigned serviceable life, while, according to ASCE, several dams have almost at the verge of end of their design life. Testing of these precious structures is necessary to maintain the safety. The robot, named “crawler bot”, will cost few dollars by automating the testing process.

Few Words from Project Manager

The senior project manager, Electric Power Research Institute (EPRI), Maria Guimaraes says “We were previously testing this is laboratories only. Now the real-word results are awesome,” about the test of robot conducted near Niagara on Robert Moses Hydroelectric Dam. When a structure needs inspection, we usually use rappels workers or scaffolding down the utility, says Guimaraes.  The robot could minimize or completely eliminate the need to send the worker up and down the structures. “The full combined system is a whole new thing for me,” she says.

Crawler Bot or Concrete Testing

Crawler bot is a modified version of a marketable available robot by ICM (International Climbing Machines), an Ithaca manufacturer. A 110-volt vacuum is installed in robot, which creates a vacuum suction chamber between its tracks, helping the bot to be stick to the wall. The friction between the foam tracks is very low hence allowing the robot to uphold the suction that is so strong that it can carry weight up to 40 lbs. and even cross over bolts, nuts or cracked concrete. “When I tried to remove it from the wall, I simple was unable to do it,” says Guimaraes. Another step to achieve was to install the sensors on robot to test the concrete.

Investigators from numerous universities and research assemblies, including the ERPI, equipped the robot with numerous non-destructive evaluation (NDE) systems to judge thestructural integrity of the structure. Acoustic sensor was used to check the delamination at the Niagara test by Guimaraes and her mates. An “air coupling” mechanism was used by sensor, meaning that the structure will not be touched by the sensor to check the delamination, according to Guimaraes. New York Power Authority partially funded the test and help them to get access the dam and its secret historical data, without which it was not possible to perform the test. NYPA will consider the areas indicated by the robot, when the will repair the dam in 2014.

Future Plans:

For future, the researcher plans to install the sensors on robot to check the level of the moisture in concrete wall and the integrity of reinforcement. The robot is equipped with a microwave antenna to tests the concrete’s reinforcement. “The plan is that we can change the robot’s sensor type and let it keep running,” says Guimaraes. After choosing the correct sensors, the robot will follow a predetermined path and records the regions where it finds problems in the utility.

The need of the test was just felt after the release of a report by Nuclear Energy Standards Coordination Collaborative (NESCC), stating the new recommendations for the improvement of repairing work for nuclear plant concrete and showing the gaps and conflicts with the existing and old standards and codes. The NESCC also stats that there is no implemented code currently for the repair of nuclear plants. It decides to change it soon which will increase the popularity and demand for Guimaraes robot.

Guimaraes and the team hope to have a commercial version of the robot by 2016, but she says there are still many tests that must take place before that can happen.

The Water Cycle Controlled by Sun

NASA: Asteroid coming close in 2032 no concern

This is an artist impression obtained from The University of Warwick and The University of Cambridge shows a rocky and water-rich asteroid being torn apart by the strong gravity of the white dwarf star GD 61. AFP PHOTO / Image copyright Mark A. Garlick, space-art.co.uk, The University of Warwick and The University of Cambridge

WASHINGTON: NASA says a big asteroid that whizzed by Earth last month unnoticed is probably nothing to worry about when it returns much closer in 19 years.
NASA Near-Earth Object program manager Donald Yeomans said there is a 1 in 48,000 chance that the 1,300-foot (400-meter) asteroid will hit Earth when it returns on Aug. 26, 2032.
The asteroid called 2013 TV135 was discovered Oct. 8, nearly a month after it came within 4.2 million miles (6.7 million kilometers) of Earth. Yeomans said as astronomers observe and track it better, they will likely calculate that it has no chance of hitting Earth.
Although big, the asteroid is considerably smaller than the type that caused the dinosaur extinction.
NASA posted a "reality check" about the asteroid in response to some media reports.

Fuel Exhaust Disrupts Scent Signals for Honeybees

Even “clean” diesel and biofuel generate gases that pose threat to pollinators.

A honeybee investigates an oilseed rape flower. A new study provides evidence of how fuel exhaust changes the chemical composition of floral odors, scrambling the scent signals for pollinators.

Photograph by Nigel Cattlin, Alamy

Helen Thompson for National Geographic

Published October 3, 2013

Fuel Exhaust Disrupts Scent Signals for Honeybees

To a bee, no two flowers smell quite the same. When honeybees forage for flowers, they search for, learn, and memorize distinctive floral scents and return to the hive to tell other bees what they’ve found through their famouswaggle dance.

It is an important ritual that is being disrupted by one of the most pervasive forms of air pollution—diesel exhaust—according to a new study published Thursday in Scientific Reports. The research pinpoints the mechanism by which the fuel-combustion pollutants degrade certain chemicals in floral odors. The absence of those chemicals affects honeybees’ ability to recognize the scent. (See related quiz: “What You Don’t Know About Cars and Fuel.”)

Engine exhaust is hardly the only threat facing the honeybee. It is well recognized that exposure to multiple pesticides can impair bees’ olfactory skills, while ground-level ozone, or smog, and ultraviolet (UV) radiation can also degrade floral odor compounds that bees pick up on. Authorities around the globe are grappling with how to address the little-understood cyclical diseases that are causing colonies to dwindle. (See related, “The Plight of the Honeybee.”)

The new study offers insight into the specific hazard for pollinators from the fumes from cars, trucks, trains, ships, and heavy machinery. Significantly, the study indicates that honeybees haven’t been helped by the "cleaner" diesel now used in Europe and the United States due to regulations that over the past decade removed sulfur from the fuel. The researchers used ultra-low-sulfur diesel fuel in their experiment. (See related: “Pictures: Cars That Fired Our Love-Hate Relationship With Fuel.”)

Odor Cues

Thousands of chemical compounds contribute to flower odors, so honeybees (Apis mellifera) need a discerning sense of smell. “A honeybee might see a red flower, and say oh is this a flower that I want to visit, and [it] uses odor cues to figure out if it’s worth visiting,” said Quinn McFrederick, an ecologist at Fresno State University in California. Odor cues can tell bees which flowers have the most nutritious nectar and pollen for harvesting.

Scientists have long thought that air pollution masked these key floral scents, but the new study provides evidence of how the exhaust actually changed the chemical composition of the odors. Using an odor palette from a common target for honeybees, oilseed rape flowers (Brassica napus), a research team at the University of Southampton in the United Kingdom exposed the compounds to diesel fumes from a generator fueled by ultra-low-sulfur diesel. Almost immediately, the diesel fumes started breaking down two of the flower odor compounds: farnesene and terpinene. After training honeybees recognize the flower scent, the researchers removed both degraded compounds from the mix.

“To our surprise, really, we saw that even changes in one of the very minor constituents of the mixture caused a major change in the responsiveness of the bee to the smell,” said Tracey Newman, a neurobiologist at the University of Southampton and a co-author of the study.

The researchers said one component of diesel exhaust takes the blame for this degradation: NOx gases, compounds that contain both nitrogen and oxygen, reacting with volatile floral odors. Although the scientists used diesel fuel, which powers the majority of cars in Europe and nearly all heavy vehicles around the world, NOx gases also are emitted by gasoline, or petrol, and even alternative fuels like biodiesel and ethanol. (See related, “Biofuel at a Crossroads.”) “The bottom line is I don’t think one can start pointing one’s finger at biodiesel, diesel, or petrol,” said Guy Poppy, an ecologist and co-author on the study. It’s a larger issue with internal combustion engines, he said.

Both the United States and the European Union use nitrogen dioxide (NO2) levels as a proxy for all NOx gases and have set limits for the amount of NO2 in the air, but not for nitric oxide (NO) levels. Poppy said, “These are the sorts of emissions that are sometimes left out from the discussions about climate change because these emissions are not ones as heavily associated with greenhouse gases.” (See related “Pictures: A Rare Look Inside Carmakers’ Drive for 55 MPG.”)

Flower Chemistry

Oilseed rape flowers aren’t the sweetest smelling blooms. “They’re actually a bit stinky,” Newman said. But, their odors are very well understood, and these two degraded compounds appear to be a key element of odor communication for bees. Other bee species and other pollinators rely even more heavily on scent over longer distances. So, the findings could have major implications for other pollinators as well, said McFrederick, who was not affiliated with the study.

Interestingly, the degraded compounds in this experiment were present only at low levels, and removing terpinene by itself led to a significant decline in bee recognition in the experiment. “That suggests that that in some way kicks off a particular pathway in the odor perception abilities of the animal,” said Newman.

The researchers’ next step is to look at the impact of diesel on the honeybee nervous system.

How will these findings play out in the real world? “The study clearly illustrates that airborne pollution can perniciously impact the ability of bees to locate food,” said Jose Fuentes, a meteorologist at Penn State University who was not associated with the study. Fuentes spelled out two cautions: The experimental levels of pollutants were high even for urban rush hour; and the impact of the NOx gases might actually be an indirect one. That’s because NOx gases notoriously react with air and sunlight to make ground-level ozone, or smog, which may be the actual culprit in disrupting the floral odor compounds.

Urban environments expose honeybees and flowers to more diesel exhaust, but there are many important factors affecting the success of hives. The kind of neighborhood gardens found in urban and suburban areas also might provide bees with longer lasting food sources than in rural areas. Field studies could shed more light on the impact of air pollution.  “What we need to know is [for] a flower sitting in a field next to a car in a motorway, whether there actually is going to be a plume of smell coming from that flower and whether it’s going to be significantly affected because of the exhaust fumes,” said Poppy. The worst-case scenario would be to find a drastic reduction in honeybee foraging and pollination.

While it’s unclear how much impact diesel pollutants might have on pollination, the new study indicates that exhaust should be added to a growing list of known threats.

“Honeybees living in a modern world face many stresses,” including diseases, insecticides, and atmospheric pollutants, Poppy said. “Probably bees can cope with most of these stresses in isolation or when just two or three of them come together. But, when they all come together simultaneously, one might start to see significant effects and that might explain some of the things we’re seeing … with pollinators being lost around the world.”

Fuel Exhaust Disrupts Scent Signals for Honeybees

Building Design Cosiderations

Building Design

• Environmental requirements
• Structural requirements
• Aesthetic requirements
• Cost constraints
• Dimensional constraints
• Statutory requirements
• Life of the building
• Manufacturing and erection considerations

WALLS

Walls are the vertical elements of a building which enclose the space within it and which may also divide that space

Functional Requirements

• strength and stability
• weather resistance
• fire resistance
• thermal insulation
• sound insulation

Form of Construction

• Masonry (e.g. brickwalls)
• Monolithic (e.g. concrete walls)
• Frame (e.g. timber stud)
• Membrane (e.g. sandwich)

Strength

Resistance to:

• stresses set up by its own weight
• superimposed loads
• lateral pressure (e.g. wind)

Stability

Resistance to:

• overturning by lateral force
• buckling caused by excessive slenderness

PERFORMANCE

Weather Resistance

Provide adequate resistance to rain and wind penetration:

• adequate thickness [for external walls, minimum 150mm - concrete; 225mm - brickwork]
• adequate damp proofing means at critical position

Fire Resistance

Walls can act as Fire Barriers to compartmentalise a building so that a fire is confined to a given area.
They can separate specific fire risks within a building to form safe escape routes.

Thermal Insulation

Act as barriers:

• to prevent heat loss to the environment (in "cool" areas)
• to prevent heat gain (in "hot" areas)

Sound Insulation

Requirements to prevent airborne sound and impact sound:

• external walls
• internal walls (prevention of passage of sound from one space to another)

MATERIALS

Types of Bricks & Blocks

• Clay bricks
• Calcium silicate bricks
• Concrete bricks
• Clay blocks
• Dense concrete blocks
• Aerated (lightweight) concrete blocks

Types of Mortars

• cement sand mortar
• cement lime sand
• cement sand with plasticiser
• lime and sand

Brickwall Strength

Slenderness Ratio

The slenderness ratio of a wall and the eccentricity of the load will indicate whether the wall will crush or buckle. The greater the slenderness and eccentricity, the sooner buckling will occur.
Slenderness Ratio = (Effective length or height) / Effective width
effective width - least lateral dimension

Effective Length

The effective length or height of a wall depends on how the wall is held at its ends or points of lateral support.

Major Elements in a Building

Relationship Between Foundation and Loading

A Framed Building