Smart window that tints and powers itself invented

NTU Prof Sun Xiaowei holding his smart window invention that can self-tint and also functions as a battery. Credit: Image courtesy of Nanyang Technological University

Nanyang Technological University (NTU) scientists have developed a smart window which can darken or brighten without the need for an external power source.

This unique self-tinting window requires zero electricity to operate and is also a rechargeable battery. The window's stored energy can be used for other purposes, such as to light up low-powered electronics like a light emitting diode (LED).

Currently, the window solutions in the market are either using permanent tinting which cannot brighten at night or are windows that can change its light transmission properties only with an external power source.

The NTU smart window however can be turned into a cool blue tint in bright daylight, cutting light penetration by about half, and then reverts back to clear glass at night or as required.

This breakthrough research led by NTU Professor Sun Xiaowei, was published recently in Nature Communications.

How it works

The trick to making the self-powered smart window is a new technology developed by Prof Sun's team from NTU's School of Electrical and Electronic Engineering.

"Our new smart electrochromic window is bi-functional; it is also a transparent battery," Prof Sun explained. "It charges up and turns blue when there is oxygen present in the electrolyte -- in other words, it breathes."

The NTU smart window contains liquid electrolyte placed in between two glass sheets coated with indium tin oxide (ITO), commonly used as transparent conductive coatings for television displays. One sheet is coated with an additional layer of a pigment known as Prussian Blue and the other one is attached to a thin strip of aluminium foil. The Prussian Blue gives the glass a blue tint when it is fully charged.

The two glass sheets are connected by typical electrical cables. When the electrical circuit between them is broken, a chemical reaction starts between Prussian Blue and the dissolved oxygen in the electrolyte, turning the glass blue. To turn off the blue tint, the electrical circuit is closed to discharge the battery, turning the Prussian Blue into a colourless Prussian White.

Such an innovative technology can adjust the amount of sunlight coming into buildings in the day, which promises significant savings on cooling and lighting costs.

"Our technology is very attractive as a zero-sum consumption smart window. Buildings owners and even common households can reap energy savings right from the outset and over the long term. Developers who are looking at constructing environmentally-friendly green buildings will find our technology attractive for their building plans," said Prof Sun.

Prof Sun is an electrical engineering expert whose other innovations include various solar technologies, glass-free 3D technologies, next-generation lightings and displays.

The NTU team, consisting of five researchers, is now enhancing their invention and is looking forward to collaborating with industry partners to commercialise their technology.

Source: Nanyang Technological University

Software to automatically outline bones in x-rays

An image from the Bone Finder software. Credit: Image courtesy of Manchester University

Research into disorders such as arthritis is to be helped by new software developed at the University of Manchester which automatically outlines bones -- saving thousands of hours of manual work.

Amidst a national shortage of radiographers in the UK and an increasing requirement for researchers to work with large databases of radiograph images, the software which is being funded by the Engineering and Physical Sciences Research Council, is being designed to automatically pick out the shapes of bones in the images, rather than relying on individual researchers.

The system can already identify hips, but the researchers from the University's Institute of Population Health will now adapt it to map out knees and hands and to be able to learn to identify other bones and structures within the body.

The funding will allow further development to ensure the system is accurate enough that it can be used in hospitals to help provide faster diagnosis of problems in patients.

Professor of Computer Vision, Tim Cootes said: "Mapping the outlines of bones from radiographs is hard work that takes time and skill. When researchers into conditions like arthritis are working with hundreds of images, it's a very inefficient way of obtaining data.

"The idea of this software is to take the routine tasks out of human hands, so scientists can 

focus on drawing conclusions and developing treatments."

The funding of £300,000 lasts for three years and builds on earlier work which developed software, called Bonefinder, to identify problems and find the outlines of hips. This free software has been adopted by a number of research groups, including some based in Oxford and California.

Professor Cootes added: "We have a growing problem with arthritis which affects more than 30% of over 65s and costs around £30 billion to the UK economy year.

"Ultimately we want to get this technology into hospitals where it can save time and resources for the benefit of patients."

Source: Manchester University

Defects in solar cells made of silicon identified

Sergio Castellanos wants continue researching, work in an industry and does not rule out to eventually move to another country. Credit: Image courtesy of Investigación y Desarrollo

Since he was a teenager, engineer Sergio Castellanos had the desire to study abroad to prepare and do research in the best laboratories, particularly on solar energy. With six years of stay in the United States, first at the University of Arizona and now at the Massachusetts Institute of Technology (MIT) in Boston, his dream has come true:

"Working on defects found on silicon and their impact on the efficiency of solar cells made with this material."

This research is carried out to obtain his doctorate from MIT.

"Dislocation is a defect that occurs at high temperatures, of 500 ° C onwards. In my research I analyze these defects and their impact on the efficiency of solar cells made from silicon, since this material is used in over 90 percent of solar panels worldwide ."

The Mexican researcher in Boston explains that the harmful part of the dislocation is interacting with other defects such as metallic impurities within the material of solar cells; they tend to reduce efficiency by -for example- interacting with electrons.

"When having a dislocation is very easy for impurities to settle into a defect in the material. Therefore, in my research I analyze at an early scale what kind of dislocations will be more harmful to the cells, meaning, which ones will interact more with impurities because not all do likewise, hence not all dislocations are equally harmful."

The proposal of Sergio Castellanos at the MIT is to apply a method in wafers of polycrystalline silicon before being processed into solar cells. This method involves using a chemical treatment in order to view the dislocations and analyze the geometric variation on the surface. After making crystallographic analysis as well as X-rays for determining the distribution and concentration of metal impurities, a correlation is made with the geometric appearance of the surface and then, just by looking at the surface, one can deduce what the electrical behavior within material will be.

"The goal is to identify which areas of the material will be more likely for electrons to recombine before being extracted by contacts, becoming less efficient cells."

A little bit of history

When the native of Hermosillo, Sonora (northern state of Mexico), was in high school, he applied for the Massachusetts Institute of Technology (MIT) and was not admitted. He told himself he would not be discouraged because surely the opportunity would could come later. He decided to study mechanical engineering at the Technological Institute of Hermosillo and two years in his parents supported him to finish his degree abroad.

He was transferred to the University of Arizona where he finished his degree. At the university, he became involved in several projects on the subject of energy, as was the case with hydrogen cells, a solar car and installing solar panels.

The Mexican says he enjoyed doing research and started looking for projects and teachers who worked in that area. He spotted four scientists, but wanted to go to MIT because "for any engineer to be in this school is a dream. I had practice in energy research during my bachelor's and for my doctorate I looked for subjects in this area. I applied at several universities and at last I was admitted at MIT in Boston."

His research in solar cells is in the last stage, and once completed in the next year he will make it available to other researchers. This work was presented at various conferences and has received good reviews in terms of utility.

To "finish the tale" on solar cells, the Mexican will complete his studies in six to eight months, and is more than satisfied with the subject that has developed during his research.

Sergio Castellanos wants continue researching, work in an industry and does not rule out to eventually move to another country. In the remaining months he will define his next step. (Agencia ID)

Source: Investigación y Desarrollo

Cheaper 3-D virtual reality system: Powerful enough for a gamer, made for an engineer

It's like a scene from a gamer's wildest dreams: 12 high-definition, 55-inch 3D televisions all connected to a computer capable of supporting high-end, graphics-intensive gaming.
Credit: Image courtesy of Brigham Young University

It's like a scene from a gamer's wildest dreams: 12 high-definition, 55-inch 3D televisions all connected to a computer capable of supporting high-end, graphics-intensive gaming.

On the massive screen, images are controlled by a Wii remote that interacts with a Kinnect-like Bluetooth device (called SmartTrack), while 3D glasses worn by the user create dizzying added dimensions.

But this real-life, computer-powered mega TV is not for gaming. It's for engineering.

Welcome to Brigham Young University's VuePod, a 3D immersive visualization environment run by BYU's Department of Civil and Environmental Engineering. Student-built and operated, under the supervision of civil engineering professor Dan Ames, the VuePod is changing the way engineers are viewing environmental engineering challenges.

"This is gold," said fellow BYU civil engineering professor Kevin Franke. "This technology has the ability to revolutionize my job as an earthquake engineer."

That's because the VuePod allows users to virtually fly over, wander through or hover above 3D environments that are otherwise difficult to visit. The images are created by point data from aircraft equipped with LIDAR (think RADAR, but with lasers). The LIDAR scans the landscape and records millions of data points that are then viewed as an image on the VuePod. Point data can also be created from stitched-together photographs taken from low-cost drones, which is Franke's research focus.

One set of data currently available for study in the VuePod captured a canyon area beneath a plateau in southern Idaho. With 3D glasses and the Wii controller, a user can virtually drop down into the canyon from above, and then fly from one end to the other.

As cool as it is to fly through a canyon, the real engineering application comes in when you combine two sets of data for the same canyon, taken five years a part. With the second set of data, changes in the natural landscape that are invisible to the human eye become clear as day. Thanks to the VuePod's massive 108-square-foot screen, all of the image-making data can be presented for viewing.

"Our eyes and our brains are so amazing; we need to take full advantage of them," Ames said. "That's the value of this project: we're presenting more information for the human eyes to detect changes."

In addition to natural change detection, the VuePod has the potential to assist in infrastructure monitoring -- such as tracking how highways hold up (or slough and crack) over time and seeing the affect on buildings after severe weather or earthquakes.

While the VuePod is certainly not the first immersive visualization system in academia, it may just be the most cost efficient built to date. Some systems cost as much as $10 million to build and maintain, while BYU's VuePod just barely topped the $30,000 mark.

Ames details how BYU was able to build such a powerful system for so little in a new paper published by the Journal of Computing in Civil Engineering.

"Our question has been: How can we make this technology accessible?" Ames said. "We're trying to determine the threshold for getting the most function at the most affordable cost. Ultimately, the goal is to take an expensive tool and make it cheaper for an everyday engineering firm to use."

And even though Ames and his students have achieved that, they believe much more can be done.

"We want whoever reads this paper to be able to build a better system than we built," he said.

Source: Brigham Young University

Hack the planet? Geoengineering research, ethics, governance explored

A conceptualized image of a wind-powered, remotely controlled ship that could seed clouds over the ocean to deflect sunlight.

Hacking Earth's climate to counteract global warming -- a subject that elicits strong reactions from both sides -- is the topic of a December special issue of the journal Climatic Change. A dozen research papers include the most detailed description yet of the proposed Oxford Principles to govern geoengineering research, as well as surveys on the technical hurdles, ethics and regulatory issues related to deliberately manipulating the planet's climate.

University of Washington researchers led the three-year project to gather leading thinkers and publish a snapshot of a field that they say is rapidly gaining credibility in the scientific community.
"In the past five years or so, geoengineering has moved from the realm of quackery to being the subject of scientific research," said co-editor Rob Wood, a UW associate professor of atmospheric sciences. "We wanted to contribute to a serious intellectual discourse."

Creating clouds over the ocean that would reflect back sunlight is the subject of a chapter by Wood, whose research is on the interaction among air pollution, clouds and climate. He and co-author Tom Ackerman, a UW atmospheric sciences professor, look at what it would take to test the idea with a field experiment.

"I don't want to prove it right, I just want to know if it's feasible," Wood said. "If you look at the projections for how much Earth's air temperature is supposed to warm over the next century, it is frightening. We should at least know the options. Is geoengineering feasible if there were to be what people call a 'climate emergency'?"

Also explored in the journal issue is the idea of injecting reflective particles into the stratosphere, subject of a 2006 paper in Climatic Change by Nobel Prize-winning chemist Paul Crutzen and central to Seattle entrepreneur Nathan Myhrvold's proposed StratoShield. Yet another idea is iron fertilization of ocean microbes, though Wood said preliminary tests suggest this is not as successful at drawing carbon dioxide out of the atmosphere as its proponents had originally thought.

How to govern geoengineering is a topic of hot debate. In one paper, U.K. authors flesh out the so-called Oxford Principles, which suggest how geoengineering could be regulated as a global public good. The five principles described in the paper concern the research, publication, assessment and deployment of geoengineering techniques.

Many of the authors spoke at the UW during a 2011 seminar series, and more attended a 2012 workshop where they developed their paper ideas.

While discussions were civil, Wood said, the contributors didn't all agree. A UW philosopher questions whether geoengineering can even be described in the Oxford Principles as a global public good.

"Just spraying sulfates into the stratosphere is not the kind of thing that necessarily benefits everyone, so in that sense it seems a mistake to call it a global public good," said co-editor Stephen Gardiner, a UW philosophy professor who has written a book on ethics and climate change. There are decisions about how to conduct sulfate spraying, he writes, and potential tradeoffs between short-term benefits and long-term risks.

Gardiner also questions whether something should be done in people's benefit but without their permission, and if accepting geoengineering as a necessary evil ignores other science or policy options.

He's not the only social scientist to be looking at climate issues.
"A lot of people, from across the academy, are getting interested in the Anthropocene -- the idea that we may have entered a new geological era where human influence is a dominant feature, and what that means for various issues," Gardiner said.

The collection aims to prompt a serious academic discussion the editors say has so far been lacking.
"It's an interdisciplinary discussion with an emphasis on the research angle -- whether and how we should be researching geoengineering," said co-editor Lauren Hartzell-Nichols, a UW lecturer in philosophy. "We hope it helps people think about this issue in a more interdisciplinary and integrated way."

The seminars and workshop that led to the issue's creation were supported by the UW College of the Environment.

Source: University of Washington

Scientist offers better ways to engineer Earth's climate to prevent dangerous global warming

There may be better ways to engineer the planet's climate to prevent dangerous global warming than mimicking volcanoes, a University of Calgary climate scientist says in two new studies.

Releasing engineered nano-sized disks, or sulfuric acid in a condensable vapor above the Earth, are two novel approaches. These approaches offer advantages over simply putting sulfur dioxide gas into the atmosphere," says David Keith, a director in the Institute for Sustainable Energy, Environment and Economy and a Schulich School of Engineering professor.

Keith, a global leader in investigating this topic, says that geoengineering, or engineering the climate on a global scale, is an imperfect science.

"It cannot offset the risks that come from increased carbon dioxide in the atmosphere. If we don't halt man-made CO₂ emissions, no amount of climate engineering can eliminate the problems -- massive emissions reductions are still necessary."

Nevertheless, Keith believes that research on geoengineering technologies, their effectiveness and environmental impacts needs to be expanded.

"I think the stakes are simply too high at this point to think that ignorance is a good policy."

Keith suggests two novel geoengineering approaches -- 'levitating' engineered nano-particles, and the airborne release of sulfuric acid -- in two newly published studies. One study was authored by Keith alone, and the other with scientists in Canada, the U.S. and Switzerland.

Scientists investigating geoengineering have so far looked mainly at injecting sulfur dioxide into the upper atmosphere. This approach imitates the way volcanoes create sulfuric acid aerosols, or sulfates, that will reflect solar radiation back into space -- thereby cooling the planet's surface.

Keith says that sulfates are blunt instruments for climate engineering. It's very difficult to achieve the optimum distribution and size of the aerosols in the atmosphere to reflect the most solar radiation and get the maximum cooling benefit.

One advantage of using sulfates is that scientists have some understanding of their effects in the atmosphere because of emissions from volcanoes such as Mt. Pinatubo, he adds.

"A downside of both these new ideas is they would do something that nature has never seen before. It's easier to think of new ideas than to understand their effectiveness and environmental risks," says Keith.

In his study-published in the Proceedings of the National Academy of Sciences, Keith describes a new class of engineered nano-particles that might be used to offset global warming more efficiently, and with fewer negative side effects, than using sulfates.

According to Keith, the distribution of engineered nano-particles above the Earth could be more controlled and less likely to harm the planet's protective ozone layer.

Sulfates also have unwanted side-effects, ranging from reducing the electricity output from certain solar power systems, to speeding up the chemical process that breaks down the ozone layer.

Engineered nano-particles could be designed as thin disks and built with electric or magnetic materials that would enable them to be levitated or oriented in the atmosphere to reflect the most solar radiation.

It may also be possible to control the position of particles above the Earth. In theory, the particles might be engineered to drift toward Earth's poles, to reduce solar radiation in polar regions and counter the melting of ice that speeds up polar warming-known as the ice-albedo feedback.

"Such an ability might be relevant in the event that warming triggers rapid deglaciation," Keith's study says.

"Engineered nano-particles would first need to be tested in laboratories, with only short-lived particles initially deployed in the atmosphere so any effects could be easily reversible," says Keith.

Research would also be needed to determine whether such nano-particles could be effectively distributed, given the complex interplay of forces in the atmosphere, and how much cooling might be achieved at the planet's surface.

It is also unknown whether the amount of particles needed-about 1 trillion kilograms per year or 10 million tonnes over 10 years-could be manufactured and deployed at a reasonable cost.

However, Keith notes another study, which looked at the cost of putting natural sulfates into the stratosphere.

"You could manipulate the Earth's climate at large scale for a cost that's of the order of $1 billion a year. It sounds like a lot of money, but compared to the costs of managing other environmental problems or climate change, that is peanuts."

"This is not an argument to do it, only an indication that risk, not cost, will be the deciding issue," he adds.

In a separate new study published in the journal Geophysical Research Letters, Keith and international scientists describe another geoengineering approach that may also offer advantages over injecting sulfur dioxide gas.

Releasing sulfuric acid, or another condensable vapor, from an aircraft would give better control of particle size. The study says this would reflect more solar radiation back into space, while using fewer particles overall and reducing unwanted heating in the lower stratosphere.

The study included computer modeling that showed that the sulfuric acid would quickly condense in a plume, forming smaller particles that would last longer in the stratosphere and be more effective in reflecting solar radiation than the large sulfates formed from sulfur dioxide gas.

Keith stresses that whether geoengineering technology is ever used, it shouldn't be seen as a reason not to reduce man-made greenhouse gas emissions now accumulating in the atmosphere.

"Seat belts reduce the risk of being injured in accidents. But having a seat belt doesn't mean you should drive drunk at 100 miles an hour," he says.

Source: University of Calgary

Stop Emitting Carbon Dioxide, Or Geoengineering Could Be Only Hope For Earth's Climate, Experts Warn

A new report finds that unless future efforts to reduce greenhouse gas emissions are much more successful than they have been so far, additional action in the form of geoengineering will be necessary if we are to cool the planet. Credit: iStockphoto/Andrey Prokhorov

The future of the Earth could rest on potentially dangerous and unproven geoengineering technologies unless emissions of carbon dioxide can be greatly reduced, the latest Royal Society report has found.

The report (published September 1, 2009 by the Royal Society, the UK’s national academy of science) found that unless future efforts to reduce greenhouse gas emissions are much more successful than they have been so far, additional action in the form of geoengineering will be necessary if we are to cool the planet. Geoengineering technologies were found to be very likely to be technically possible and some were considered to be potentially useful to augment the continuing efforts to mitigate climate change by reducing emissions. However, the report identified major uncertainties regarding their effectiveness, costs and environmental impacts.

Professor John Shepherd, who chaired the Royal Society’s geoengineering study, said, “It is an unpalatable truth that unless we can succeed in greatly reducing CO₂emissions we are headed for a very uncomfortable and challenging climate future, and geoengineering will be the only option left to limit further temperature increases. Our research found that some geoengineering techniques could have serious unintended and detrimental effects on many people and ecosystems - yet we are still failing to take the only action that will prevent us from having to rely on them. Geoengineering and its consequences are the price we may have to pay for failure to act on climate change.”

The report assesses the two main kinds of geoengineering techniques – Carbon Dioxide Removal (CDR) and Solar Radiation Management (SRM). CDR techniques address the root of the problem – rising CO₂ – and so have fewer uncertainties and risks, as they work to return the Earth to a more normal state. They are therefore considered preferable to SRM techniques, but none has yet been demonstrated to be effective at an affordable cost, with acceptable environmental impacts, and they only work to reduce temperatures over very long timescales.

SRM techniques act by reflecting the sun’s energy away from Earth, meaning they lower temperatures rapidly, but do not affect CO₂ levels. They therefore fail to address the wider effects of rising CO₂, such as ocean acidification, and would need to be deployed for a very long time. Although they are relatively cheap to deploy, there are considerable uncertainties about their regional consequences, and they only reduce some, but not all, of the effects of climate change, while possibly creating other problems. The report concludes that SRM techniques could be useful if a threshold is reached where action to reduce temperatures must be taken rapidly, but that they are not an alternative to emissions reductions or CDR techniques.

Professor Shepherd added, “None of the geoengineering technologies so far suggested is a magic bullet, and all have risks and uncertainties associated with them. It is essential that we strive to cut emissions now, but we must also face the very real possibility that we will fail. If “Plan B” is to be an option in the future, considerable research and development of the different methods, their environmental impacts and governance issues must be undertaken now. Used irresponsibly or without regard for possible side effects, geoengineering could have catastrophic consequences similar to those of climate change itself. We must ensure that a governance framework is in place to prevent this.”

Of the CDR techniques assessed, the following were considered to have most useful potential:

• CO₂ capture from ambient air – this would be the preferred method of geoengineering, as it effectively reverses the cause of climate change. At this stage no cost-effective methods have yet been demonstrated and much more research and development is needed.
• Enhanced weathering – this technique, which utilises naturally occurring reactions of CO₂ from the air with rocks and minerals, was identified as a prospective longer-term option. However more research is needed to find cost-effective methods and to understand the wider environmental implications.
• Land use and afforestation – the report found that land use management could and should play a small but significant role in reducing the growth of atmospheric CO2 concentrations. However the scope for applying this technique would be limited by land use conflicts, and all the competing demands for land must be considered when assessing the potential for afforestation and reforestation. Should temperatures rise to such a level where more rapid action needs to be taken, the following SRM techniques were considered to have most potential:
• Stratospheric aerosols – these were found to be feasible, and previous volcanic eruptions have effectively provided short-term preliminary case studies of the potential effectiveness of this method. The cost was assessed as likely to be relatively low and the timescale of action short. However, there are some serious questions over adverse effects, particularly depletion of stratospheric ozone.
• Space-based methods – these were considered to be a potential SRM technique for long-term use, if the major problems of implementation and maintenance could be solved. At present the techniques remain prohibitively expensive, complex and would be slow to implement.
• Cloud albedo approaches (eg. cloud ships) – the effects would be localised and the impacts on regional weather patterns and ocean currents are of considerable concern but are not well understood. The feasibility and effectiveness of the technique is uncertain. A great deal more research would be needed before this technique could be seriously considered.

The following techniques were considered to have lower potential:

• Biochar (CDR technique) – the report identified significant doubts relating to the potential scope, effectiveness and safety of this technique and recommended that substantial research would be required before it could be considered for eligibility for UN carbon credits.
• Ocean fertilisation (CDR technique) – the report found that this technique had not been proved to be effective and had high potential for unintended and undesirable ecological side effects.
• Surface albedo approaches (SRM technique, including white roof methods, reflective crops and desert reflectors) – these were found to be ineffective, expensive and, in some cases, likely to have serious impacts on local and regional weather patterns.

Source: The Royal Society

Can a stack of computer servers survive an earthquake?

The rack of servers shook, but did not fall, during a simulation that mimicked 80 percent of the force of 1994's Northridge earthquake. Credit: Cory Nealon, University at Buffalo

How do you prevent an earthquake from destroying expensive computer systems?

That's the question earthquake engineer Claudia Marin-Artieda, PhD, associate professor of civil engineering at Howard University, aims to answer through a series of experiments conducted at the University at Buffalo.

"The loss of functionality of essential equipment and components can have a disastrous impact. We can limit these sorts of equipment losses by improving their seismic performance," Marin-Artieda said.
In buildings such as data centers, power plants and hospitals, it could be catastrophic to have highly-sensitive equipment swinging, rocking, falling and generally bashing into things.

In high-seismic regions, new facilities often are engineered with passive protective systems that provide overall seismic protection. But often, existing facilities are conventional fixed-base buildings in which seismic demands on sensitive equipment located within are significantly amplified. In such buildings, sensitive equipment needs to be secured from these damaging earthquake effects, Marin-Artieda said.
The stiffer the building, the greater the magnification of seismic effects, she added.

"It is like when you are riding a rollercoaster," she said. "If your body is relaxed, you don't feel strong inertial effects. But if you hold your body rigid, you'll feel the inertial effects much more, and you'll get knocked about in the car."

The experiments were conducted this month at the University at Buffalo's Network for Earthquake Engineering Simulation (NEES), a shared network of laboratories based at Purdue University.
Marin-Artieda and her team used different devices for supporting 40 computer servers donated by Yahoo Labs. The researchers attached the servers to a frame in multiple configurations on seismically isolated platforms. They then subjected the frame to a variety of three-directional ground motions with the servers in partial operation to monitor how they react to an earthquake simulation.

Preliminary work confirmed, among other things, that globally and locally installed seismic isolation and damping systems can significantly reduce damage to computer systems and other electronic equipment.

Base isolation is a technique that sets objects atop an energy-absorbing base; damping employs energy-absorbing devices within the object to be protected from an earthquake's damaging effects.
Marin-Artieda plans to expand the research by developing a framework for analysis, design and implementation of the protective measures.

The research is funded by the National Science Foundation. In addition to Yahoo Labs, industry partners include Seismic Foundation Control Inc., The VMC Group, Minus K Technology Inc., Base Isolation of Alaska, and Roush Industries Inc. All provided in-kind materials for the experiments.

Video showing one of the tests, which mimics 80 percent of the force of 1994's Northridge earthquake: https://www.youtube.com/watch?v=hTkemnt8hR4

Source: University at Buffalo

The Ground-improvement methods might protect against earthquakes

Researchers are using T-Rex, a 64,000-pound shaker truck, in research to increase the resilience of homes and low-rise structures built on top of soils prone to liquefaction during strong earthquakes. T-Rex is based at a University of Texas at Austin facility that is part of the George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES), a distributed laboratory with 14 sites around the United States. Credit: NEES photo

Researchers from the University of Texas at Austin's Cockrell School of Engineering are developing ground-improvement methods to help increase the resilience of homes and low-rise structures built on top of soils prone to liquefaction during strong earthquakes.

Findings will help improve the safety of structures in Christchurch and the Canterbury region in New Zealand, which were devastated in 2010 and 2011 by a series of powerful earthquakes. Parts of Christchurch were severely affected by liquefaction, in which water-saturated soil temporarily becomes liquid-like and often flows to the surface creating sand boils.

"The 2010-2011 Canterbury earthquakes in New Zealand have caused significant damage to many residential houses due to varying degrees of soil liquefaction over a wide extent of urban areas unseen in past destructive earthquakes," said Kenneth Stokoe, a professor in the Department of Civil, Architectural and Environmental Engineering. "One critical problem facing the rebuilding effort is that the land remains at risk of liquefaction in future earthquakes. Therefore, effective engineering solutions must be developed to increase the resilience of homes and low-rise structures."
Researchers have conducted a series of field trials to test shallow-ground-improvement methods.
"The purpose of the field trials was to determine if and which improvement methods achieve the objectives of inhibiting liquefaction triggering in the improved ground and are cost-effective measures," said Stokoe, working with Brady Cox, an assistant professor of civil engineering. "This knowledge is needed to develop foundation design solutions."

Findings were detailed in a research paper presented in December at the New Zealand -- Japan Workshop on Soil Liquefaction during Recent large-Scale Earthquakes. The paper was authored by Stokoe, graduate students Julia Roberts and Sungmoon Hwang; Cox and operations manager Farn-Yuh Menq from the University of Texas at Austin; and Sjoerd Van Ballegooy from Tonkin & Taylor Ltd, an international environmental and engineering consulting firm in Auckland, New Zealand.

The researchers collected data from test sections of improved and unimproved soils that were subjected to earthquake stresses using a large mobile shaker, called T-Rex, and with explosive charges planted underground. The test sections were equipped with sensors to monitor key factors including ground motion and water pressure generated in soil pores during the induced shaking, providing preliminary data to determine the most effective ground-improvement method.

Four ground-improvement methods were initially selected for the testing: rapid impact compaction (RIC); rammed aggregate piers (RAP), which consist of gravel columns; low-mobility grouting (LMG); and construction of a single row of horizontal beams (SRB) or a double row of horizontal beams (DRB) beneath existing residential structures via soil-cement mixing.

"The results are being analyzed, but good and poor performance can already be differentiated," Stokoe said. "The ground-improvement methods that inhibited liquefaction triggering the most were RIC, RAP, and DRB. However, additional analyses are still underway."

The test site is located along the Avon River in the Christchurch suburb of Bexley. The work is part of a larger testing program that began in early 2013 with a preliminary evaluation by Brady Cox of seven potential test sites along the Avon River in the Christchurch area.

Funding for the research has been provided, in part, by the National Science Foundation and is affiliated with the NSF's George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES). The remainder of the funding has been provided by the Earthquake Commission of the New Zealand Government.

The 64,000-pound T-Rex, operated by NEES@UTexas at UT Austin, is used to simulate a wide range of earthquake shaking levels.

NEES is a shared network of 14 experimental facilities, collaborative tools, centralized data repository and earthquake simulation software, all linked by high-speed Internet connections.

Source: Purdue University