Screening tools to detect lung, heart disease developed by two high school students

Two Michigan high school students, sisters Ilina and Medha Krishen, have developed screening tools using electronic stethoscopes to detect lung and heart disease. The sisters will present their findings at CHEST 2014 in Austin, Texas next week. Credit: The Krishen family

Two Michigan high school students, sisters Ilina and Medha Krishen, have developed screening tools using electronic stethoscopes to detect lung and heart disease. The sisters will present their findings at CHEST 2014 in Austin, Texas next week.

Ilina Krishen became aware of the dangers of smoking and chemical air pollution when she saw the effects of lung disease on family members. Curious to find a way to detect early lung damage in people exposed to noxious air pollutants, Ilina, a high school senior at Port Huron Northern High School in Michigan, developed a screening mechanism using an electronic stethoscope. An electronic stethoscope overcomes the problem of low sound levels by electronically amplifying body sounds, using an electromagnetic diaphragm that captures the diaphragm movement as an electrical signal.

Ilina recruited 16 smokers, 13 firefighters, and 25 nonsmokers for her test. The electronic stethoscope recorded one breath cycle from each volunteer. Frequency peaks were used to analyze the frequency distribution of breath sounds. Differences of peaks above 125 Hz were analyzed.

Ilina found that the number of peaks was significantly higher in smokers and firefighters, even if the firefighters were nonsmokers. She realized that although firefighters wear protective masks when fighting fires, they often do not wear masks when making a second check of the building after the fire is out. "The firefighters are exposed to many poisonous chemicals that remain in the air after the fire has gone out," said Ilina. "Screening with an electronic stethoscope may be able to detect early changes in lung function in individuals without symptoms of lung disease."

Medha Krishen, Ilina's sister and a junior at Port Huron Northern High School, also presented a study that used an electronic stethoscope to screen student athletes for hypertrophic cardiomyopathy (HCM).

Medha studied 13 individuals: 10 with a normal cardiac sports physical and three with a diagnosis for HCM. Heart sounds were recorded in 5-second periods while the athletes were lying down, standing, and after exercise. Frequency peaks of a frequency amplitude plot were analyzed. Studies showed a significant difference in the distribution of frequency peaks in the two groups between the lying down position and after exercise. Normal athletes showed a lower percentage of peaks above 131 Hz after exercise, while the athletes at risk showed a rise in frequency peaks following exercise.

"When I was in fifth grade, a family friend died after exercise, and I always wanted to learn more about how to prevent something like that happening," said Medha. "My study analyzing heart sound frequencies may be a useful technique that school staff could use to screen for HCM."

The sisters are both athletes -- Ilina is a varsity tennis player, and Medha is an accomplished figure skater -- and they take a personal interest in the health of athletes. They are also nonsmokers and hope to encourage others not to smoke. After Ilina completed her study and showed her study subjects the results of her tests "two or three of the smokers have quit smoking, and that makes me feel good," says Ilina.

Source: American College of Chest Physicians

Sculpting costumes with 3-D printers is 'the way theater is headed,' say theater education experts

Baylor junior Mackenzie Dobbs, a theatre performance major, in a witch's costume decorated with beans and mushrooms produced from a 3D printer. Credit: Drapers: Sylvia Fuhrken and Ryan Schapp, Photo by Jared Tseng

Three-dimensional printers, which already have churned out jewelry, prosthetic limbs and one fully functioning car, are taking the stage -- literally -- in another arena: live theater.

They allow greater speed, flexilibity, creativity -- and can appease directors who change their minds mid-rehearsal.

Synthetic beans and mushrooms -- accessories for the cursed, hump-backed witch in a Baylor University production of the musical "Into the Woods" -- recently emerged from a little machine tucked away in a corner of the costume shop at Baylor. And that's only the beginning for the new printer, says former Disneyland costume designer/wardrobe coordinator Joe Kucharski, assistant professor of theatre arts at Baylor.

Using his computer mouse and some free software, Kucharski tugged, flattened and pinched a digital "ball of clay" into the desired shapes: rotting vegetables, including two dozen beans and a dozen mushrooms. That done, the 3D printer heated and spun plastic cord into the delicate thread to create the costume elements for the witchy wardrobe.

Depending on the size and how complicated a design is, 3D printing may take 20 minutes to a couple hours.

"You can set a few buttons and walk away during printing," Kucharski said. "You can customize and print multiples, and you can use colors that are the whole range of the rainbow.

"Designers are always thinking, 'How can we design quickly but keep it adjustable so we're ready if the director says, 'Well, we're kinda there. . .'? We can go back and tweak quickly."

The printers have been used in film and fashion, and "it's a great application for scenic design in theater, too," he said. "You can use miniatures created on a small-scale model and save time instead of carving little details."

The 3D printer is rapidly becoming part of the "designer tool bag." While students still need to learn traditional drawing and creating, incorporating 3D technology into curriculum for costume and prop design can give them an edge in the job market.

"This is the way theatre is going," said Stan Denman, Ph.D., chair and professor of theatre arts at Baylor. "This even lets us create items that are no longer being produced -- like brooches or hatpins -- for period plays. Otherwise, because those things are antiques, the cost is prohibitive.

"This also can be helpful if you have an item that has to be broken in a scene," he said. "You can have multiple items to replace it for repeat performances."

Source: Baylor University

‘Fury’ tanks in safe hands

Fury Sherman. Credit: Image courtesy of Bournemouth University

BU research engineers have been working on military vehicles that feature in Brad Pitt's new movie.

Set in the Second World War and currently in UK cinemas, 'Fury' sees Pitt's character Wardaddy command a Sherman tank.

Scenes from the movie were filmed at the Tank Museum at Bovington, where the BU research team are investigating how to preserve these historic vehicles.

The team have worked on the Sherman and Tiger 1, which can be seen in the Fury movie trailer (2 minutes 26 seconds in). Researchers Adil Saeed, Dr Zulfiqar Khan, and Professor Mark Hadfield from BU's Sustainable Design Research Centre have published widely on these particular vehicles.

Dr Zulfiqar Khan said, "This movie reflects the importance of the research, which examines how we can preserve these vehicles for the benefit of society for lengths of time that far exceed the basis any normal design intent.

"The centenary of the First World War and the passing of the generation that fought in the Second World War, means the conservation of significantly degraded vehicle collections has taken on a new importance."

The Tank Museum at Bovington is one of the largest military vehicle museums in the world, boasting a collection of over 300 military vehicles with historic significance. Structural deterioration through corrosion, corrosion fatigue, stress corrosion cracking and mechanical failures are a threat to these vehicles in terms of conservation.

The only operational Tiger tank in the world is currently at The Tank Museum at Bovington. This and other vehicles had to be conserved sustainably, while operating modestly for the annual Tank Fest and other events.

Dr Khan concluded, "The opportunity of collaborative research with The Tank Museum at Bovington to develop sustainable methodology of conserving historic military tanks brought us face to face with the history. This research investigated the state of the structural integrity of vehicles used in WW1, WW2 and post war.

"The outcomes of the research informed the current design of control environment in The Tank Museum. In addition a separate research project looked into the cost implications of project management of The Tank Museum.

"This kind of activity is important in engaging new generations with science, technology, maths and mechanical engineering design solutions."

The research has led to further collaborations with Defence Science & Technology Laboratory Ministry of Defence to develop corrosion condition monitoring and predictive modelling techniques.

Source: Bournemouth University

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 70-foot-long, 52-ton concrete bridge survives series of simulated earthquakes

A new, rocking, pre-tensioned concrete bridge support system has been developed by the University of Washington that reduces on-site construction time and minimizes earthquake damage. The 52-ton, 70-foot-long concrete bridge, built atop three 14- by 14-foot, 50-ton-capacity hydraulically driven shake tables at the University of Nevada, Reno, was shaken in a series of simulated earthquakes, culminating in the large ground motions recorded in the deadly and damaging 1995 magnitude 6.9 earthquake in Kobe, Japan.

A 70-foot-long, 52-ton concrete bridge survived a series of earthquakes in the first multiple-shake-table experiment in the University of Nevada, Reno's new Earthquake Engineering Lab.

"It was a complete success. The bridge withstood the design standard very well and today went over and above 2.2 times the design standard," John Stanton, civil and environmental engineering professor and researcher from the University of Washington, said. Stanton collaborated with Foundation Professor David Sanders of the University of Nevada, Reno in the novel experiment.

"The bridge performed very well," Sanders said. "There was a lot of movement, about 12 percent deflection -- which is tremendous -- and it's still standing. You could hear the rebar inside the columns shearing, like a zipper opening. Just as it would be expected to do."

The set of three columns swayed precariously, the bridge deck twisted and the sound filled the cavernous laboratory as the three 14- by 14-foot, 50-ton-capacity hydraulically driven shake tables moved the massive structure.

"Sure we broke it, but we exposed it to extreme, off-the-scale conditions," Stanton said. "The important thing is it's still standing, with the columns coming to rest right where they started, meaning it could save lives and property. I'm quite happy."

The bridge was designed and the components were pre-cast at the University of Washington in Seattle, and then built atop three 14- by 14-foot, 50-ton-capacity hydraulically driven shake tables in the 24,500 square-foot lab. It was shaken in a series of simulated earthquakes, culminating in the large ground motions similar to those recorded in the deadly and damaging 1995 magnitude 6.9 earthquake in Kobe, Japan.

The rocking, pre-tensioned concrete bridge support system is a new bridge engineering design the team has developed with the aim of saving lives, reducing on-site construction time and minimizing earthquake damage.

"By building the components off-site we can save time with construction on-site, minimizing interruptions in traffic and lowering construction costs," Sanders said. "In this case, the concrete columns and beams were pre-cast and tensioned at the University of Washington. Other components were built here at the University of Nevada, Reno. It took us only a month to build the bridge, in what would otherwise be a lengthy process."

"This can't be done anywhere else in the nation, and perhaps the world," Ian Buckle, director of the lab and professor of civil engineering, said of the test. "Of course we've been doing these types of large-scale structures experiments for years, but it's exciting to have this first test using multiple tables in this building complete. It's good to see the equipment up and running successfully.

When combined with the University's Large-Scale Structures Laboratory, just steps away from the new lab, the facility comprises the biggest, most versatile large-scale structures, earthquake/seismic engineering facility in the United States, according to National Institute of Standards and Technology, and possibly the largest University-based facility of its kind in the world.

A grand opening was held recently for the $19 million lab expansion project, funded with $12.2 million by the U.S. Department of Commerce's National Institute of Standards and Technology, funds from the Department of Energy, as well as University and donor funds. The expansion allows a broader range of experiments and there is additional space to add a fifth large shake table.

"Our facility is unique worldwide and, combined with the excellence of our faculty and students, will allow us to make even greater contributions to the seismic safety of our state, the nation and the world," Manos Maragakis, dean of the College of Engineering, said. "We will test new designs and materials that will improve our homes, hospitals, offices and highway systems. Remarkable research is carried on here. Getting to this point has taken a lot of hard work. It's both a culmination and a beginning, ushering in a new era."

Source: University of Nevada, Reno

New bridge design improves earthquake resistance, reduces damage and speeds construction

This graphic illustrates a new design for the framework of columns and beams that support bridges, called "bents," to improve performance for better resistance to earthquakes, less damage and faster on-site construction. The faster construction is achieved by prefabricating the columns and beams off site and later erecting and connecting them quickly at the construction site. Credit: University of Washington, Seattle/NEES photo

Researchers have developed a new design for the framework of columns and beams that support bridges, called "bents," to improve performance for better resistance to earthquakes, less damage and faster on-site construction.

The faster construction is achieved by pre-fabricating the columns and beams off-site and shipping them to the site, where they are erected and connected quickly.

"The design of reinforced concrete bridges in seismic regions has changed little since the mid-1970s," said John Stanton, a professor in the Department of Civil and Environmental Engineering at the University of Washington, Seattle, who developed the concept underlying the new design. The team members include professor Marc Eberhard and graduate research assistants Travis Thonstad and Olafur Haraldsson from the University of Washington; and professor David Sanders and graduate research assistant Islam Mantawy from the University of Nevada, Reno.

Research findings are included in a paper being presented during Quake Summit 2014, the annual meeting for the National Science Foundation's George E. Brown, Jr. Network for Earthquake Engineering Simulation, a shared network of laboratories based at Purdue University. This year's summit is part of the 10th U.S. National Conference on Earthquake Engineering on July 21-25 in Anchorage, Alaska.

Until now the majority of bridge bents have been made using concrete that is cast in place, but that approach means time is needed for the concrete to gain strength before the next piece can be added. Pre-fabricating the pieces ahead of time eliminates this requirement, speeding on-site construction and reducing traffic delays.

"However, pre-fabricating means the pieces need to be connected on-site, and therein lies a major difficulty," Stanton said. "It is hard enough to design connections that can survive earthquake shaking, or to design them so that they can be easily assembled, but to do both at once is a real challenge."
Moreover, the researchers have achieved this goal using only common construction materials, which should smooth the way for owners and contractors to accept the new approach, he said.

An important feature of the new system is that the columns are pre-tensioned.

"A good analogy is to think of a series of a child's wooden building blocks, each with a hole through it," Stanton said. "Stack them on top of one another, put a rubber band through the central hole, stretch it tight and anchor it at each end. The rubber band keeps the blocks squeezed together. Now stand the assembly of blocks up on its end and you have a pre-tensioned column. If the bottom of the column is attached to a foundation block, you can push the top sideways, as would an earthquake, but the rubber band just snaps the column back upright when you let go."

This "re-centering" action is important because it ensures that, directly after an earthquake, the bridge columns are vertical and not leaning over at an angle. This means that the bridge can be used by emergency vehicles in the critical moments immediately following the earthquake.

"Of course, the real bridge columns do not contain rubber bands, but very high-strength steel cables are used to achieve the same behavior," Stanton said.

To keep the site operations as simple as possible, those cables are stressed and embedded in the concrete at the plant where the columns are fabricated. The columns also contain some conventional rebar, which is also installed in the fabrication plant.

The technology was pioneered in the building industry in the 1990s but is now being adapted for use with bridges.

When the columns rock during an earthquake, they experience high local stresses at the points of contact, and without special measures the concrete there would crush. To counteract this possibility, the researchers protected the ends of the columns with short steel tubes, or "jackets," that confine the concrete, not unlike the hoops of a barrel, or the steel cap that ranchers use to protect the top of a fence-post while driving it into the ground.

"Cyclic tests of the critical connections have demonstrated that the system can deform during strong earthquakes and then bounce back to vertical with minimal damage," Stanton said.

Those tests were conducted on individual connections by graduate assistants Olafur Haraldsson, Jeffrey Schaefer and Bryan Kennedy. In July, the team will test a complete bridge built with the system. The test will be conducted at 25 percent of full-scale on the earthquake-shaking tables at a facility at the University of Nevada, Reno. The facility is part of NEES.

Travis Thonstad led the design and built the components for that test. The column and cap beam components were then shipped to the University of Nevada, Reno, where Islam Mantawy is leading the construction of the bridge. The team from Washington and Nevada will be processing the data from this project, and it will be archived and made available to the public through NEES.

The Quake Summit paper was authored jointly by the team. The research was supported by the NSF, the Pacific Earthquake Engineering Research (PEER) Center and the Valle Foundation of the University of Washington.

Source: Purdue University

The Wastewater disposal may trigger quakes at greater distance than previously thought

Oil and gas development activities, including underground disposal of wastewater and hydraulic fracturing, may induce earthquakes by changing the state of stress on existing faults to the point of failure. Earthquakes from wastewater disposal may be triggered at tens of kilometers from the wellbore, which is a greater range than previously thought, according to research to be presented today at the annual meeting of the Seismological Society of America (SSA). As an indication of the growing significance of man-made earthquakes on seismic hazard, SSA annual meeting will feature a special session to discuss new research findings and approaches to incorporating induced seismicity into seismic hazard assessments and maps.

The number of earthquakes within central and eastern United States has increased dramatically over the past few years, coinciding with increased hydraulic fracturing of horizontally drilled wells, and the injection of wastewater in deep disposal wells in many locations, including Colorado, Oklahoma, Texas, Arkansas and Ohio. According to the U.S. Geological Survey (USGS), an average rate of 100 earthquakes per year above a magnitude 3.0 occurred in the three years from 2010-2012, compared with an average rate of 21 events per year observed from 1967-2000.

"Induced seismicity complicates the seismic hazard equation," said Gail Atkinson, professor of earth sciences at Western University in Ontario Canada, whose research details how a new source of seismicity, such as an injection disposal well, can fundamentally alter the potential seismic hazard in an area.

For critical structures, such as dams, nuclear power plants and other major facilities, Atkinson suggests that the hazard from induced seismicity can overwhelm the hazard from pre-existing natural seismicity, increasing the risk to structures that were originally designed for regions of low to moderate seismic activity.

A new study of the Jones earthquake swarm, occurring near Oklahoma City since 2008, demonstrates that a small cluster of high-volume injection wells triggered earthquakes tens of kilometers away. Both increasing pore pressure and the number of earthquakes were observed migrating away from the injection wells.

"The existing criteria for an induced earthquake do not allow earthquakes associated with the well activity to occur this far away from the wellbore," said Katie Keranen, assistant professor of geophysics at Cornell University, who led the study of the Jones earthquake swarm. "Our results, using seismology and hydrogeology, show a strong link between a small number of wells and earthquakes migrating up to 50 kilometers away" said Keranen. The study's result will be presented by co-author Geoff Abers, senior research scientist at Lamont-Doherty Earth Observatory.
While there are relatively few wells linked to increased seismicity, seismologists seek to anticipate when activity might trigger earthquakes and at what magnitude.

"It is important to avoid inducing earthquakes large enough to be felt, that is, earthquakes with magnitudes of about 2.5, or greater, because these are the ones that are of concern to the public," said Art McGarr, a geophysicist with USGS.

McGarr's research investigates the factors that enhance the likelihood of earthquakes induced by fluid injection that are large enough to be felt, or, on rare occasions, capable of causing damage. The injection activities considered in McGarr's study include underground disposal of wastewater, development of enhanced geothermal systems and hydraulic fracturing. Of the three activities, wastewater disposal predominates both in terms of volumes of injected liquid and earthquake size, with magnitudes for a few of the earthquakes exceeding 5.

"From the results of this study, the total volume of injected fluid seems to be the factor that limits the magnitude, whereas the injection rate controls the frequency of earthquake occurrence," said McGarr.
Despite the increasing seismicity in the central and eastern US, induced earthquakes are presently excluded from USGS estimates of earthquake hazard. Justin Rubinstein, geophysicist with USGS, will present an approach to account for the increased seismicity without first having to determine the source (induced or natural) of the earthquakes.

The USGS is trying to "stay agnostic as to whether the earthquakes are induced or natural," says Rubinstein. "In some sense, from a hazard perspective, it doesn't matter whether the earthquakes are natural or induced. An increase in earthquake rate implies that the probability of a larger earthquake has also risen," said Rubinstein, whose method seeks to balance all of the possible ways the hazard might change given the changing earthquake rate.

But what's the likelihood of induced seismicity from any specific well?
"We can't answer the question at this time," said Atkinson, who said the complex problem of assigning seismic hazard to the effects of induced seismicity is just beginning to be addressed.

"There is a real dearth of regulations," said Atkinson. "We need a clear understanding of the likely induced seismicity in response to new activity. And who is the onus on to identify the likely seismic hazard?"

Source: Seismological Society of America

The Floating nuclear plants could ride out tsunamis: New design for enhanced safety, easier siting and centralized construction

This illustration shows a possible configuration of a floating offshore nuclear plant, based on design work by Jacopo Buongiorno and others at MIT's Department of Nuclear Science and Engineering. Like offshore oil drilling platforms, the structure would include living quarters and a helipad for transportation to the site.
Credit: Illustration courtesy of Jake Jurewicz/MIT-NSE

When an earthquake and tsunami struck the Fukushima Daiichi nuclear plant complex in 2011, neither the quake nor the inundation caused the ensuing contamination. Rather, it was the aftereffects -- specifically, the lack of cooling for the reactor cores, due to a shutdown of all power at the station -- that caused most of the harm.

A new design for nuclear plants built on floating platforms, modeled after those used for offshore oil drilling, could help avoid such consequences in the future. Such floating plants would be designed to be automatically cooled by the surrounding seawater in a worst-case scenario, which would indefinitely prevent any melting of fuel rods, or escape of radioactive material.

The concept is being presented this week at the Small Modular Reactors Symposium, hosted by the American Society of Mechanical Engineers, by MIT professors Jacopo Buongiorno, Michael Golay, and Neil Todreas, along with others from MIT, the University of Wisconsin, and Chicago Bridge and Iron, a major nuclear plant and offshore platform construction company.

Such plants, Buongiorno explains, could be built in a shipyard, then towed to their destinations five to seven miles offshore, where they would be moored to the seafloor and connected to land by an underwater electric transmission line. The concept takes advantage of two mature technologies: light-water nuclear reactors and offshore oil and gas drilling platforms. Using established designs minimizes technological risks, says Buongiorno, an associate professor of nuclear science and engineering (NSE) at MIT.

Although the concept of a floating nuclear plant is not unique -- Russia is in the process of building one now, on a barge moored at the shore -- none have been located far enough offshore to be able to ride out a tsunami, Buongiorno says. For this new design, he says, "the biggest selling point is the enhanced safety."

A floating platform several miles offshore, moored in about 100 meters of water, would be unaffected by the motions of a tsunami; earthquakes would have no direct effect at all. Meanwhile, the biggest issue that faces most nuclear plants under emergency conditions -- overheating and potential meltdown, as happened at Fukushima, Chernobyl, and Three Mile Island -- would be virtually impossible at sea, Buongiorno says: "It's very close to the ocean, which is essentially an infinite heat sink, so it's possible to do cooling passively, with no intervention. The reactor containment itself is essentially underwater."
Buongiorno lists several other advantages. For one thing, it is increasingly difficult and expensive to find suitable sites for new nuclear plants: They usually need to be next to an ocean, lake, or river to provide cooling water, but shorefront properties are highly desirable. By contrast, sites offshore, but out of sight of land, could be located adjacent to the population centers they would serve. "The ocean is inexpensive real estate," Buongiorno says.

In addition, at the end of a plant's lifetime, "decommissioning" could be accomplished by simply towing it away to a central facility, as is done now for the Navy's carrier and submarine reactors. That would rapidly restore the site to pristine conditions.

This design could also help to address practical construction issues that have tended to make new nuclear plants uneconomical: Shipyard construction allows for better standardization, and the all-steel design eliminates the use of concrete, which Buongiorno says is often responsible for construction delays and cost overruns.

There are no particular limits to the size of such plants, he says: They could be anywhere from small, 50-megawatt plants to 1,000-megawatt plants matching today's largest facilities. "It's a flexible concept," Buongiorno says.

Most operations would be similar to those of onshore plants, and the plant would be designed to meet all regulatory security requirements for terrestrial plants. "Project work has confirmed the feasibility of achieving this goal, including satisfaction of the extra concern of protection against underwater attack," says Todreas, the KEPCO Professor of Nuclear Science and Engineering and Mechanical Engineering.
Buongiorno sees a market for such plants in Asia, which has a combination of high tsunami risks and a rapidly growing need for new power sources. "It would make a lot of sense for Japan," he says, as well as places such as Indonesia, Chile, and Africa.

Source: Massachusetts Institute of Technology

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