A team of students at the Johns Hopkins University’s Whiting School of Engineering has designed for NASA a new stethoscope that delivers accurate heart- and body-sounds to medics who are trying to assess astronauts’ health on long missions in noisy spacecraft.

Space is serene, because no air means no sound. But inside the average spacecraft, with its whirring fans, humming computers and buzzing instruments, is about as raucous as a party filled with laughing, talking people.

Johns Hopkins mechanical engineering students developed these components for a stethoscope that could do a better job of detecting heart sounds within a noisy space vessel. Photo: Will Kirk/homewoodphoto.jhu.edu

“Imagine trying to get a clear stethoscope signal in an environment like that, where the ambient noise contaminates the faint heart signal. That is the problem we set out to solve,” said Elyse Edwards, a senior from Issaquah, Wash., who teamed up on the project with fellow seniors Noah Dennis, a senior from New York City, and Shin Shin Cheng, from Sibu, Sarawak, Malaysia.

The students worked under the guidance of James West, a Johns Hopkins research professor in electrical and computer engineering and co-inventor of the electret microphone used in telephones and in almost 90 percent of the more than two billion microphones produced today.

Together, they developed a stethoscope that uses both electronic and mechanical strategies to help the device’s internal microphone pick up sounds that are clear and discernible – even in the noisy spacecraft, and even when the device is not placed perfectly correctly on the astronaut’s body.

“Considering that during long space missions, there is a pretty good chance an actual doctor won’t be on board, we thought it was important that the stethoscope did its job well, even when an amateur was the one using it,” Dennis said.

The project was developed during a two-semester mechanical engineering senior design course offered by the university’s Whiting School of Engineering. Teams of three or four undergraduates are each given a small budget to design and build a prototype requested by a sponsoring business or organization. This year’s results were unveiled recently at a showcase conducted shortly before the students were scheduled to graduate.

The device also includes many other performance-enhancing improvements, including low power consumption, rechargeable batteries, mechanical exclusion of ambient noise and a suction cup, so that it sticks firmly onto the patient’s chest, says Cheng.

Though developed for NASA’s use in outer space, this improved stethoscope could also be put to use here on Earth in combat situations, where ambient noise is abundant, and in developing countries, where medical care conditions are a bit more primitive.

West also plans to use the device to record infants’ heart and lung sounds in developing countries as part of a project that will attempt to develop a stethoscope that knows how to identify the typical wheezing and crackling breath sounds associated with common diseases. This would allow on-site medics to help make preliminary automated diagnoses.

Related links:
Whiting School of Engineering
Department of Mechanical Engineering

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Johns Hopkins University news releases can be found on the World Wide Web at http://www.jhu.edu/news_info/news/ Information on automatic E-mail delivery of science and medical news releases is available at the same address.

It’s a parent’s worst nightmare: a young child is accidentally left in a locked car on a warm and sunny day. The closed windows turn the car into a greenhouse, and the child dies of heatstroke.

In a key first step toward preventing such tragedies, three undergraduate engineering students at Johns Hopkins have turned technology from a popular video game player into a detector for children left behind in dangerously overheated vehicles. The young inventors tinkered with parts from a Kinect motion-sensing device, normally used with the Xbox 360 game console, and came up with the heart of a new system aimed at “seeing” children left in locked cars and summoning help.

The student inventors unveiled their child detection prototype at a recent senior design showcase. From left are Anshul Mehra, Yejin Kim and Jeffrey Kamei; at the far right is their faculty sponsor, Eileen McDonald of the the Johns Hopkins Center for Injury Research and Policy. Photo by Norman Barker/homewoodphoto.jhu.edu

Although the project needs further work, the students’ sponsor said their proof-of-concept prototype is a significant move toward reducing the number of children lost in locked-car incidents. “These are preventable deaths that deserve our attention,” said Eileen McDonald, a faculty member in the Johns Hopkins Center for Injury Research and Policy, part of the Bloomberg School of Public Health. “The students showed that they could detect even the tiniest movements associated with a child left in the backseat of a car. We don’t have a perfect model yet, but we’re hoping another group will pick up where they left off and bring it closer to becoming a commercial product.”

The project was developed during a two-semester mechanical engineering senior design course offered by the university’s Whiting School of Engineering. Teams of three or four undergraduates were each given a small budget to design and build a prototype requested by a sponsoring business or organization. This year’s results were unveiled recently at a showcase conducted shortly before the students were scheduled to graduate.

McDonald and her center challenged one of these teams to address a public health problem documented in a 2012 study released by the National Highway Traffic Safety Administration. According to the report, 527 heatstroke-related deaths involving children left in cars had been recorded in the United States since 1998, or an average of 38 such deaths annually. The study, conducted by researchers at Children’s Hospital of Philadelphia, cited the circumstances surrounding these deaths: in 51 percent of the cases, the caregivers had forgotten the children were in the car; in 30 percent of the cases, the children were playing in an unattended vehicle; and in 17 percent of the cases, an adult intentionally left the child in the vehicle. (The remaining 2 percent did not fit within these categories, or the circumstances were unknown.)

The NHTSA report also included testing results of several safety devices already being sold to alert parents that a baby or toddler has been left in the vehicle. The report stated that “the devices were inconsistent and unreliable.”

McDonald asked Johns Hopkins mechanical engineering students Jeffrey Kamei, Yejin Kim and Anshul Mehra to come up with a better way to prevent these deaths. She also encouraged them to produce a passive protection system that would operate without requiring the driver to flip a switch or hook a wristband to the child to activate it.

During brainstorming sessions last fall, the students hit on the idea of adapting the Kinect video game technology. The device uses an infrared camera and projector to sense the movements of a game player and incorporates these motions into what is happening on the video screen. The students thought the same technology could sense even the most subtle movements of a baby sleeping in a rear car-seat.

An important advantage of using infrared technology, the students said, was that it cannot penetrate the vehicle’s glass windows, so it is unlikely that a movement outside the car, such as a pedestrian or a passing vehicle, could accidentally trigger the motion detector. But inside a car, early tests indicated the sensor should be able to quickly pick up a baby or toddler who is trapped or sleeping inside.

Although the largest hurdle has been cleared, additional work must be done to complete and test the system before it can become a commercial product. First, researchers will either have to license Microsoft’s Kinect technology or develop other equipment that works in a similar way. Also on the drawing board are several options for the system to summon help when a trapped child is detected. These could include a loud alarm or an automated call to police or firefighters, or to a car security service such as OnStar.

As they prepared for graduation, the student inventors said they had gained valuable real-world engineering experience while launching a project that could have significant public health value.

When the project opportunities were posted last fall, “this was my first choice,” said Mehra, who lives in Baltimore. “Within my culture in India, family is very important. This was a project that could help prevent a big family tragedy.”

“At first it was just a cool idea, and then it evolved,” said Kamei, who is from Downey, Calif., a suburb of Los Angeles. “I think it definitely has a lot of potential.”

“I’m glad we were able to build something that could protect babies,” added Kim, a citizen of South Korea who completed her high school studies in Texas.

Notes: The 2012 NHTSA report on heatstroke and children in parked vehicles can be viewed at: http://www.nhtsa.gov/DOT/NHTSA/NVS/811632.pdf‎ . Updated statistics on heatstroke deaths of children in vehicles may be viewed on a website maintained by San Francisco State University researcher Jan Null: http://www.ggweather.com/heat/ .

Related links:

Department of Mechanical Engineering: http://www.me.jhu.edu/
Whiting School of Engineering: http://engineering.jhu.edu
Johns Hopkins Center for Injury Research and Policy: http://www.jhsph.edu/injurycenter

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Johns Hopkins University news releases can be found on the World Wide Web at http://www.jhu.edu/news_info/news/ Information on automatic E-mail delivery of science and medical news releases is available at the same address.

A Johns Hopkins faculty member who is studying how mechanical forces affect soft tissue within the eye has been named a 2013 recipient of a National Science Foundation CAREER Award. The award to Thao “Vicky” Nguyen, an assistant professor of mechanical engineering, will support research that may shed light on diseases and conditions such as tendon injuries, cardiac fibrosis and glaucoma.

Thao “Vicky” Nguyen is an assistant professor of mechanical engineering at Johns Hopkins. Photo: Will Kirk/Homewood Photography

This prestigious NSF honor, formally known as a Faculty Early Career Development award, recognizes junior faculty members who exemplify the role of teacher-scholars through outstanding research, excellent education and the integration of education and research in their organizations.

Nguyen’s research in general focuses on understanding the complex mechanics of soft adaptive materials. Her new CAREER award is for a project called “Understanding the Micromechanisms of Growth and Remodeling Collagenous Tissues.” The award comes with $400,000 in research funding that will be allocated over a five-year period that began Jan. 1. The funds will support the work of one graduate student in Nguyen’s lab and cover a portion of the faculty member’s salary.

For this project, Nguyen will focus specifically on the sclera—the white outer layer of the eyes—in experimental glaucoma mice that are subjected to increased intraocular pressure. This research has the potential to add significantly to the understanding of how mechanical forces influence the growth and remodeling of collagen tissue. The findings could lead to new treatments for glaucoma and other collagen-related disorders.

Outside of the health field, Nguyen’s research into the mechanical behavior of soft active polymers also has potential aerospace and security applications.

Nguyen was born in Vietnam. Her family immigrated to California when she was in elementary school. After moving to the San Fernando Valley area of Los Angeles, she attended a math/science magnet school program in Van Nuys, which encouraged her interest in these subjects. Nguyen went on to complete her undergraduate college studies at the Massachusetts Institute of Technology, and then earned her master’s and doctoral degrees at Stanford University, all in mechanical engineering.

She spent three years as a senior member of the technical staff of Sandia National Laboratories before joining the Whiting School of Engineering faculty at Johns Hopkins in 2007.

She was subsequently selected as a recipient of a 2008 Presidential Early Career Award for Scientists and Engineers, nominated by the U.S. Department of Energy.

Color photo of Vicky Nguyen available; contact Phil Sneiderman.

Related links:

Vicky Nguyen’s Lab Website: http://me.jhu.edu/tnguy108/Homepage/Homepage.html
Department of Mechanical Engineering: http://me.jhu.edu/
Whiting School of Engineering: http://engineering.jhu.edu

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Johns Hopkins University news releases can be found on the World Wide Web at http://www.jhu.edu/news_info/news/ Information on automatic E-mail delivery of science and medical news releases is available at the same address.

Recipes can be rather imprecise: a dab of butter, a pinch of salt. But Johns Hopkins engineering students recently learned that maintaining rigid control of cooking temperatures, with less than 1 degree of wiggle-room, can lead to much tastier meals.

Oddly enough, their cooking experiments occurred in an undergraduate course called Robot Sensors and Actuators. Class instructor Noah Cowan, an associate professor of mechanical engineering, assigned his students to tinker with common cooking appliances such as toaster ovens or water heating tools. Their revamped appliance had to operate under the control of sensors, actuators and a microprocessor, programmed by the students.

The goal was to devise a system that could sense the temperature of the cooking medium, trigger steps to get the air or water to a particular level of heat—and keep it there. The system had to work like the familiar thermostat that regulates a home’s heating and air conditioning, but with much greater precision.

From left, course instructor Noah Cowan directs students Larry Wu, Meng Wang and Nicha Apichitsopa to calibrate the salinity test for the water they use to cook shrimp. Image: Will Kirk / Homewood Photography

Because Cowan himself likes to cook, he decided to mix this high-tech task with some lessons about Sous Vide, an increasingly popular way of preparing food. In the Sous Vide method, the food is vacuum-sealed in a bag and immersed in hot water to cook at a relatively low, but constant temperature, generally for a longer period than in traditional cooking. Proponents say this method produces meats, poultry, fish and vegetables that are more evenly cooked and boast superior flavor and texture. To allow his students to learn more about this technique and about molecular gastronomy (the science of cooking), Cowan arranged for his class to visit the Waterfront Kitchen in Baltimore, where Chef Jerry Pellegrino shared insights.

“We set up the trip to the restaurant because I wanted part of this course to be fun,” Cowan said. “But I also wanted to show the students that all of that math and all of that engineering they’ve been learning could be applied immediately to the world of cooking. I like seeing students learn about the broad application of the engineering skills they’ve been developing here.”

Student Jasper Stroud was part of a team that used the Sous Vide method to cook hamburgers that were vacuum-sealed and immersed in heated water. Image: Will Kirk / Homewood Photography

For the course’s final project, the 64 students divided into 22 teams and built their own cooking systems. The results were unveiled at a class gathering that was part device-testing time and part potluck sampling session.

A few students showed how to use modified toaster ovens to produce veggie pizzas and “perfect toast.” One team devised an egg-cooking system with a basket that immersed its cargo when the water reached the right temperature and lifted it out when the cooking was complete.

But most projects pursued the Sous Vide option, using sensors and other electronic components to control heaters that maintain a steady cooking temperature in a pot of water. This method yielded Chinese dumplings, sweet potato fries, a dessert called Strawberry Champagne, cinnamon apples, shrimp, chocolate malted milk custard for ice cream and some fondue made from melted chocolate chips. Many students praised the Sous Vide approach. “If you keep it at an even temperature, you never have to worry about overcooking,” said Steven Lin, a mechanical engineering major who was part of the Strawberry Champagne team.

This vacuum-bag technique also produced evenly heated hamburgers, although the student cooks had to give each burger a brief searing in a pan afterward to make it resemble one of its char-broiled cousins. “We were skeptical about the whole concept,” said team member Kevin Keenahan, a biomedical engineering major. “We were afraid they’d be mushy, but they turned out to be really good. I wish I had a vacuum sealer so I could try this at home.”

Inside this cooking pot is a digital temperature sensor and an induction heater. The sensor is plugged into a microprocessor development board used in  robotics courses.  Image: Will Kirk / Homewood Photography

Still, the key purpose of the course was to teach the students how to build and use the “smart controller” that kept the cooking temperature constant. Course instructor Cowan pointed out that these controllers are widely used beyond the kitchen in many industrial applications. In the weeks leading up to the device demonstrations, some students discovered that assembling and “tuning” their sensors, actuator and microprocessors was a challenging task.

In assigning this project, Cowan said he deliberately left a few steps out of the recipe. “I didn’t tell them about everything that is likely to go wrong,” he said. “If their project worked perfectly the first time, they wouldn’t learn anything. Sometimes, a stumbling block is useful. When the students get past it, it’s exciting to see the light bulb go on.”

Adam Weiner, a dual major in mechanical engineering and physics who was part of the veggie pizza team, said he enjoyed the class. “It was fun to see it all come together in the end,” he said. “It was a struggle, and we made some mistakes, but we learned a lot.”

Sean Bailey, a biomedical engineering major whose team cooked cinnamon apples, added, “We learned to make food for our final [exam]. That’s a good thing!”

Online video and digital photos available; contact Phil Sneiderman.

Related links:

Whiting School of Engineering: http://engineering.jhu.edu

Noah Cowan’s Lab Page: http://limbs.lcsr.jhu.edu/User:Ncowan

Johns Hopkins Department of Mechanical Engineering: http://www.me.jhu.edu/

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Johns Hopkins University news releases can be found on the World Wide Web at http://www.jhu.edu/news_info/news/ Information on automatic E-mail delivery of science and medical news releases is available at the same address.

In Freshman Engineers’ Inventions, Batteries are NOT Required – or Even Allowed

WHEN: 1:30 to 3 p.m. on Wednesday, Dec. 5, 2012.

WHERE: On stage in the Shriver Hall Auditorium on The Johns Hopkins University’s Homewood campus, 3400 N. Charles St., Baltimore, Md. (Media camera crews will be allowed on stage.) Shriver Hall is Building 3 on the campus map that can be downloaded from this site: http://www.parking.jhu.edu/images/JHU_Homewood_Parking_Map_070828_1.pdf
Parking is available in the nearby South Garage.

WHO: Sixty-seven Johns Hopkins freshmen from an introductory mechanical engineering course will compete. Twenty-five student teams have built aerial vehicles that must move across elevated cables and drop a “payload” onto a target five feet below. The challenge: these cable cars can possess no motors or batteries. All movement must come from mousetraps and rubber bands.

WHAT: For a class project, each team had to design a device powered only by the energy in no more than two mousetraps and six rubber bands. Other materials, such as balsa wood and wheels, can be added, but the total cost per vehicle cannot exceed $15. Each device must move under its own power along an 8-foot-long level stretch of cable. Midway across the line, the device must drop a balloon filled with salt onto a bull’s-eye target.

THE CONTEST: Two parallel cables will be strung across a portion of the Shriver Hall stage. In a series of elimination matches, two student devices will be launched across the cables. The winner of each match will be the cable car that has the best score on the target. When the elimination rounds end, a prize will be awarded to the winning team.

WHY: While working on their projects, students have been learning about design approaches, potential and kinetic energy, friction, prototyping methods and other topics relevant to mechanical engineering. In addition, the project requires teamwork and careful planning, which both will be important in an engineering workplace.

CONTEST JUDGE AND FACULTY SUPERVISOR FOR THE EVENT: Steven Marra, a senior lecturer in the Department of Mechanical Engineering, teaches the course and will serve as judge. “We assigned this project partly because a lot of incoming engineering students have not had much experience in actually designing and building something,” Marra said. “A lot of their beliefs about how something works on paper do not necessarily work in a real-world project.” Prior to the competition, Marra can be interviewed by calling his office, 410-516-0034.

To obtain detailed rules and guidelines regarding the student competition, contact Phil Sneiderman: prs@jhu.edu or 443-287-9960.

A video about a previous Johns Hopkins mousetrap and rubber band design competition involving student-built ground vehicles can viewed here: http://www.youtube.com/watch?v=Y3DhgSXha-M

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Johns Hopkins University news releases can be found on the World Wide Web at http://www.jhu.edu/news_info/news/ Information on automatic E-mail delivery of science and medical news releases is available at the same address.

August 27, 2012
MEDIA CONTACT: Amy Lunday
Office: (443) 287-9960; Cell: (410) 804-2551
acl@jhu.edu

Hurricane-related Damage and Coastal Erosion in the Gulf and New Orleans
Tropical Storm Isaac is expected to become a hurricane by the time it reaches New Orleans, a city that was nearly destroyed by Hurricane Katrina seven years ago this week. For Robert A. Dalrymple, an internationally recognized expert on water waves and coastal engineering, this is familiar territory: He was a member of the first engineering team to determine the causes of the levee failures in New Orleans as a member of the American Society of Civil Engineers’ disaster response team. Dalrymple is often one of the first people on the ground in the wake of a waterborne natural disaster to analyze the damage and devise plans for better outcomes after future storms. He chaired a National Research Council committee that examined the Army Corps of Engineers’ plans to provide hurricane protection to southern Louisiana. In June, Dalrymple was named to the Water Institute of the Gulf science and engineering advisory council. Chair of the American Society of Civil Engineers’ Coastal Engineering Research Council and a past president of the Association of Coastal Engineers, Dalrymple has written numerous scholarly articles and a textbook on water wave mechanics and how powerful waves can damage harbor structures and buildings constructed near the shore. He is a professor of civil engineering in the Whiting School at Johns Hopkins.

Big Storms and the Power Grid
Hurricanes and other severe storms can play havoc with local power systems, causing short- and long-term outages affecting homes, businesses and public services. Dennice Gayme, an assistant professor of mechanical engineering, studies ways to improve the sustainability, reliability and efficiency of the electric power grid. Her research focuses on large-scale integration of energy storage and alternative energy systems such as wind and solar power systems, into traditional electrical grids. She and her collaborators investigate power grid stability, peak usage scheduling, power grid interconnectivity and the most effective geographic placement of energy storage facilities and wind power plants. Gayme, who grew up in Toronto, earned a doctorate in control and dynamical systems in 2010 at the California Institute of Technology. She remained at Caltech as a postdoctoral fellow, focusing on power system networks. She joined the faculty of Johns Hopkins’ Whiting School of Engineering in January 2012.

Hurricanes and Hospitals
High winds and heavy rain may not cause structural damage to hospital buildings, but power outages, downed phone lines and limited access to water can all become major problems for health care providers during a hurricane. Judith Mitrani-Reiser studies the functionality of healthcare facilities during natural disasters like earthquakes and hurricanes, using her expertise as a civil engineer to help hospitals care for patients during crises. She was on the ground in Chile shortly after the devastating earthquake in February 2010 to study its impact on the hospitals there. Mitrani-Reiser found that even with backup systems, like generators and stockpiles of water, care was often inadequate. “Nonstructural damage causes lifeline outage, economic losses, loss of functionality, and building downtime,” Mitrani-Reiser explained to Johns Hopkins Engineering magazine. “Hospitals are critical structures that need to operate continuously after a disaster. They not only need to take care of their existing patients, but meet the needs of the patients who have been hurt by the event.” Mitrani-Reiser was also on the ground in Christchurch, New Zealand, a few days after the major earthquake there in February 2011.

To speak to Dalrymple, Gayme, or Mitrani-Reiser, contact Amy Lunday at 443-287-9960 or acl@jhu.edu.

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Johns Hopkins University news releases can be found on the World Wide Web at http://releases.jhu.edu/
Information on automatic E-mail delivery of science and medical news releases is available at the same address.

]]> http://releases.jhu.edu/2012/08/27/tropical-storm-isaac/feed/ 0 http://releases.jhu.edu/2012/06/19/paddle-vs-propeller-which-olympic-swimming-stroke-is-superior/ http://releases.jhu.edu/2012/06/19/paddle-vs-propeller-which-olympic-swimming-stroke-is-superior/#comments Tue, 19 Jun 2012 19:23:41 +0000 phil http://releases.jhu.edu/?p=6870 June 19, 2012
Media Contact: Phil Sneiderman
Office: (443) 287-9960; Cell: 410-299-7462
prs@jhu.edu

Two swimming strokes—one that pulls through the water like a boat paddle and another that whirls to the side like a propeller—are commonly used by athletes training for the Olympic Games. But elite swimmers and their coaches have long argued over which arm motion is more likely to propel an aquatic star toward a medal.

A university research study has picked a winner. A team supervised by a Johns Hopkins fluid dynamics expert has found that the deep catch stroke, resembling a paddle, has the edge over sculling, the bent-arm, propeller-inspired motion.

“This is a result that is simple but sweet, which is something we usually struggle to arrive at in research,” said Rajat Mittal, a mechanical engineering professor in Johns Hopkins’ Whiting School of Engineering. “The deep catch stroke is more efficient and effective than the sculling stroke.”

Rajat Mittal

To obtain this result, Mittal’s team started with high-precision laser scans and underwater videos of elite swimmers. The researchers then used animation software to bend and otherwise change the shape of the static arm in such a way as to match the video sequence. This software allowed the researcher to insert a “joint” into the arm so that the limb could be moved in a realistic manner. The team then ran computer simulations to study the flow of fluid around the arm and the forces that acted upon the limb. Each simulation involved about 4 million degrees of freedom and required thousands of hours of computer processing time.

The findings concerning the deep catch and sculling strokes were featured in the doctoral thesis of Alfred von Loebbecke, who studied under Mittal, and in a report by Loebbecke and Mittal that has been accepted for publication in the Journal of Biomechanical Engineering.

Mittal, a recreational swimmer, joined the Johns Hopkins faculty in 2009. His research into motion through water began almost a decade ago when, while based at George Washington University, he was awarded a U.S. Navy grant to figure out how fish use their fins to swim so well. To tackle this task, Mittal’s team developed software and computer models to study the movement of marine animals.

Mittal later contacted USA Swimming to see if he might use these high-tech tools to crack the secrets of elite swimmers. Russell Mark, the biomechanics coordinator of USA Swimming, was intrigued, and he provided Mittal’s team with underwater videos of top swimmers and startup funding. With this support, Mittal and Loebbecke collaborated on studies of the “dolphin kick” used by many Olympic-caliber swimmers, including medalist Michael Phelps.

After completing that study for USA Swimming, Mittal’s team turned its attention to the debate among top coaches about the merits of deep catch and sculling strokes.

In the 1960s, the sculling stroke gained popularity thanks to the late James “Doc” Counsilman, then the head men’s swimming coach at Indiana University. Counsilman, highly regarded for his science-based approach to swimming stroke mechanics, also was head coach of the U.S. men’s swim team that won a combined 21 gold medals in the 1964 and 1976 Olympic Games. Counsilman encouraged his swimmers to use the propeller-like sculling stroke, in which the elbow is raised to a higher position and the arm moves inward and outward in an S-shaped, propeller-like pattern.

While supervising the current study, Johns Hopkins’ Mittal considered Counsilman’s reasoning. “A propeller, when it rotates, is producing a lift force, and it is that lift force that pushes a boat forward,” Mittal said. “Counsilman believed that to travel efficiently in a fluid, a swimmer should be using lift forces.”

This contradicted the advice given by many swimming instructors. “In the past, the analogy for a swimming stroke was that it was like a paddle in a boat: put the paddle in the water, push it back as hard as possible,” Mittal said. “This is called drag-based propulsion. You’re actually dragging the water back, and the water drags you forward.”

Counsilman insisted that the lift force—generated by that propeller-like movement—was a more effective way of producing thrust than drag force. But Mittal and Loebbecke’s research suggests that the fluid dynamics of this stroke are more complicated than the renowned coach had imagined.

“Sculling, in my view, is a swimming stroke that is based on an incomplete understanding of fluid mechanics,” Mittal said. “We found that Doc Counsilman was not correct overall about the sculling, but in some ways he was more correct than he would have ever thought. We did find that lift is indeed a major component in thrust production for both strokes, and that certainly indicates that the arm does not behave simply like a paddle. However, the simulations also indicate that exaggerated sculling motions, which are designed to enhance and exploit lift, actually reduce both the lift and drag contributions to thrust. So, lift is in fact important, but not in the way envisioned by these early coaches who were trying to bring fluid mechanics into swimming.”

Mittal has shared his findings with USA Swimming. He also pointed out that many top swimmers use variations of the classic deep catch and sculling strokes.

Outside of competitive swimming, Mittal’s findings could be useful in designing exoskeleton suits that the U.S. Navy is seeking to help elite military forces swim more quickly and efficiently.

At the same time, Mittal said, the research could have more down-to-earth applications by steering recreational swimmers toward the most effective strokes. “People sometimes stop swimming because they feel they are not doing it well enough,” he said. “If this research can help recreational swimmers swim more effectively and feel better about their swimming at an early stage, I think that could have an impact on health and fitness.”

Color digital video available; contact Phil Sneiderman.

Related links:
Rajat Mittal’s Lab Page: http://www.me.jhu.edu/fsag/People/faculty.html
Johns Hopkins Department of Mechanical Engineering: http://www.me.jhu.edu/

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Johns Hopkins University news releases can be found on the World Wide Web at http://www.jhu.edu/news_info/news/ Information on automatic E-mail delivery of science and medical news releases is available at the same address.

The Johns Hopkins University has won an award worth up to $90 million from the U.S. Army to tap the expertise of the nation’s top academic researchers to help the Army develop new lightweight materials to better protect soldiers and vehicles. Toward this goal, Johns Hopkins is forming a new institute where researchers will try to understand precisely what happens when impacts on materials result in “extreme dynamic environments.”

The Hopkins Extreme Materials Institute (HEMI) will focus, in particular, on what happens to protective materials at the moment of intense impact, when a large amount of energy enters a small space in a very short period of time.

“The vision of the institute is to tackle the science issues associated with extreme events and in this case to work with the Army to better protect our troops,” said K. T. Ramesh, the Alonzo G. Decker, Jr. Professor of Science and  Engineering at Johns Hopkins University’s Whiting School of Engineering, founding director of the institute and a professor of mechanical engineering.

“This is how I think about our effort with the Army,” Ramesh said. “Captain America needs a new shield, and we’re going to work with the Army to build it.”

Ramesh said the new institute’s researchers will delve into the basic science—down to the atomic level—of what happens to metals, ceramics, polymers and other materials that are subjected to an extreme impact. “What affects the material is the huge amount of energy landing all at once,” Ramesh said. “You can’t develop a new protective material until you can understand what happens to it in extreme environments. Yet we must be able to design new materials if we want to protect ourselves from yet-unforeseen threats.”

To launch this effort, the U.S. Army Research Laboratory on April 16 agreed to provide up to $90 million to a consortium of scientists from American universities, national laboratories and private industry, all affiliated with the new Johns Hopkins institute, to collaborate closely on this research with Army scientists. Among the key partner institutions are Caltech, the University of Delaware and Rutgers University.  The program is planned for a five-year initial study, and if successful, it may be renewed for an additional five years.

“Johns Hopkins is proud to carry out this work on behalf of the U.S. Army,” said Lloyd B. Minor, the university’s provost and senior vice president for academic affairs. “Bringing together experts from many disciplines, the Hopkins Extreme Materials Institute will greatly enhance our understanding of protective materials, ultimately leading to better ways to protect our troops.”

K. T. Ramesh, the Alonzo G. Decker, Jr. Professor of Science and Engineering in Johns Hopkins' Whiting School of Engineering, is founding director of the Hopkins Extreme Materials Institute. Photo by Will Kirk/Homewoodphoto.jhu.edu

John M. Miller, director of the U.S. Army Research Laboratory, said, “Designing new, transformational materials for our soldiers is the aim of our Enterprise for Multiscale Research of Materials. Our two recent awards, in Materials in Extreme Dynamic Environments to the Johns Hopkins University consortium and in Multiscale Multidisciplinary Modeling of Electronic Materials to the University of Utah, will work together to provide a strong foundation for ARL’s Enterprise for Multiscale Research of Materials.  It also shows the Army’s commitment to the national Materials Genome Initiative.”

For Johns Hopkins’ Whiting School of Engineering, the monetary award is among the largest in the school’s history. The new Hopkins Extreme Materials Institute will conduct basic research across the disciplines of mechanical engineering, materials science, civil engineering, aerospace engineering and physics.

“The award not only recognizes K.T. Ramesh’s outstanding leadership and vision, but the terrific breadth and depth of expertise provided by our interdisciplinary Johns Hopkins research team and our partner institutions,” said Nicholas P. Jones, the Benjamin T. Rome Dean of the Whiting School. “Receiving it provides us with the means to advance basic science to tackle some of today’s toughest security problems. We are honored to be recognized for our ability to make a difference in this area.”

The institute will also include a strong educational and training component. Students, postdoctoral fellows, and scientists from the Army and other universities will help conduct the research. Lectures, workshops, symposia, research reviews and online mechanisms will be used to exchange ideas and best practices. The institute’s intent is to teach the world how to think about materials in extreme environments, particularly those associated with impact events.

Lightweight protection materials that are just as effective as those available today would be very valuable, but designing such materials is a major challenge. The institute’s researchers plan to use lab experiments and computer models to gain a better understanding of how materials behave when subjected to a high velocity impact. With results from this lab research, the team hopes to develop and test new lightweight materials that offer enhanced protection.

Ramesh stressed that the institute’s emphasis is conducting fundamental research, not making specific materials. He said the goal is “to produce a way of thinking that will allow the design of lightweight protective material systems that can be used for extreme dynamic conditions.”

The institute’s new ways of thinking would also be useful in planning for catastrophic events, Ramesh said. If a stray asteroid was heading toward earth, for example, institute researchers could help choose the best strategies that could divert or break up the asteroid. The institute’s approaches would also help predict the size of dust particles emitted by volcanic eruptions such as the one in Iceland that recently halted air travel. The dust data could have helped officials figure out when it was safe to fly. A similar approach would have been useful in assessing the risks from explosions such as those at the Fukushima Daiichi nuclear plant in Japan last year.

“Our vision is twofold,” Ramesh said. “The institute looks far into the future to build the basic science needed to address future threats before they become evident, while at the same time developing and providing the science and engineering tools needed to address the dynamic problems of today. We seek to improve the human condition in an increasingly insecure world by providing government, industry and national institutions with science-based tools for designing protection and mitigating risk.”

The new institute’s labs, offices and collaborative rooms will occupy roughly a third of Malone Hall, a 56,000-square-foot research building that is being built on the university’s Homewood campus. The new building will be completed in 2014. Until then, the institute will operate in existing facilities on campus.

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Johns Hopkins University news releases can be found on the World Wide Web at http://www.jhu.edu/news_info/news/ Information on automatic E-mail delivery of science and medical news releases is available at the same address.

Andrea Prosperetti, a Johns Hopkins professor who is an internationally respected expert in the mechanics of fluids, has been elected to the National Academy of Engineering, the organization has announced.

Election to the academy is considered among the highest professional distinctions accorded to an engineer. Membership honors those who have made outstanding contributions to engineering research, practice or education, and to the pioneering of new and developing fields of technology.

Prosperetti, who is the Charles A. Miller Jr. Distinguished Professor of Mechanical Engineering in the Whiting School of Engineering, was recognized for “contributions to the fundamentals and applications of multiphase flows.”

Andrea Prosperetti - Photo by Jay VanRensselaer/homewoodphoto.jhu.edu

Multiphase flows include the bottom transport of sediment in rivers, the boiling of a liquid in a power generation plant, the complex gas-liquid mixture in an oil pipeline and other situations in which solids, liquids and gases flow together. His work focuses mainly on bubble dynamics, fluid-particle flows, computational fluid dynamics and acoustics.

Prosperetti said he hopes his election to the academy, which was announced Feb. 9, will shed positive attention on his department. “I think this represents recognition for the conditions that enabled me to do good work at Johns Hopkins,” he said.

Nicholas P. Jones, the Benjamin T. Rome Dean of the Whiting School of Engineering, said he has known Prosperetti “since he was driving a Buick Skylark at Caltech, back when he was a visiting faculty member, and I was a graduate student. Having known him for this long, I can say that this is a fitting recognition for the many contributions he’s made to our understanding of some very complex problems. We are thrilled to see him recognized in this way.”

Prosperetti received a doctorate in engineering science from Caltech in 1974 and taught at the University of Milan, Italy, before joining Johns Hopkins in 1985. He is the editor-in-chief of the International Journal of Multiphase Flow. He also has served on the editorial board of the Annual Review of Fluid Mechanics and as editor for the Letters section of The Physics of Fluid.

Prosperetti is author or co-author of about 180 papers in refereed journals. He is author of the book Advanced Mathematics for Applications and is co-author of two other books.

In addition to his work at Johns Hopkins, Prosperetti is the Berkhoff Professor of Applied Physics in the Department of Applied Sciences of the University of Twente in the Netherlands.

This year the National Academy of Engineering elected 66 new members and 10 foreign associates, bringing the total U.S. membership to 2,254 and the number of foreign associates to 206.

Other Johns Hopkins faculty members who are members of the academy are Edmund Y.S. Chao, a retired School of Medicine professor of orthopedic surgery; Kenneth Keller, director of the School of Advanced International Studies’ Bologna Center; Robert A. Dalrymple, the Willard and Lillian Hackerman Professor of Civil Engineering; Murray B. Sachs, University Distinguished Service Professor of Biomedical Engineering; Eugene D. Shchukin, a Whiting School research professor emeritus; and James E. West, a research professor in the Department of Electrical and Computer Engineering.

Color digital photo of Andrea Prosperetti available; contact Phil Sneiderman.

Related links:
Andrea Prosperetti’s Web page: http://www.me.jhu.edu/prosper/
Johns Hopkins Department of Mechanical Engineering: http://www.me.jhu.edu/

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Johns Hopkins University news releases can be found on the World Wide Web at http://www.jhu.edu/news_info/news/ Information on automatic E-mail delivery of science and medical news releases is available at the same address.

Johns Hopkins engineers, recognized as experts in medical robotics, have turned their attention skyward to help NASA with a space dilemma: How can the agency fix valuable satellites that are breaking down or running out of fuel? One option—sending a human repair crew into space—is costly, dangerous and sometimes not even possible for satellites in a distant orbit.

Another idea is now getting attention: Send robots to the rescue and give them a little long-distance human help. Johns Hopkins scientists say the same technology that allows doctors to steer a machine through delicate abdominal surgery could someday help an operator on Earth fix a faulty fuel line on the far side of the moon.

From the Robotorium at Johns Hopkins' Homewood campus in Baltimore, graduate students Tian Xia, left, and Jonathan Bohren used a da Vinci medical console, behind Bohren, to control an industrial robot at NASA Goddard Space Flight Center 30 miles away. The test showed how medical robotics technology could help repair and refuel space satellites. Photo by Will Kirk/Homewoodphoto.jhu.edu

A brief preview of this technology was presented Nov. 29, when two graduate students at Johns Hopkins’ Homewood campus in Baltimore used a modified da Vinci medical console to manipulate an industrial robot at NASA’s Goddard Space Flight Center in Greenbelt, Md., about 30 miles away. The demonstration took place during a tour of Goddard by three members of Maryland’s congressional delegation: U.S. Sen. Barbara Mikulski and U.S. Reps. Donna Edwards and Steny Hoyer.

In this demonstration, the da Vinci console was the same type that doctors use to conduct robotic surgery on cancer and cardiac patients. It included a 3D eyepiece that allowed the operator in Baltimore to see and guide the robot at Goddard. It also provided haptic, or “touch,” feedback to the operator. The goal, Johns Hopkins engineers say, is to adapt some robotic operating room strategies to help NASA to perform long-distance “surgery” on ailing satellites.

“We’re using the expertise we’ve developed in medical robotics technology and applying it to some of the remote-controlled tasks that NASA wants space robots to perform in repairing and refueling satellites,” said Louis Whitcomb, a Johns Hopkins mechanical engineering professor who was at Goddard to help supervise the recent demonstration.

Goddard is the home of NASA’s Satellite Servicing Capabilities Office, which was set up in 2009 to continue NASA’s 30-year legacy of satellite servicing and repair, including missions to the Hubble Space Telescope. Its aims are to develop new ways to service satellites and to promote the development of a U.S. industry for conducting such operations.

To move toward these goals, NASA provided a research grant to West Virginia University, which in turn picked Johns Hopkins as a partner because of the school’s expertise in medical robotics. One task the team has worked on is the use of a remote-controlled robot to carefully cut the plastic tape that holds a satellite’s thermal insulation blanket in place. The tape must be cut and the blanket pulled back in order to expose the satellite’s refueling port. A long-distance test of this procedure, in which an operator at Johns Hopkins will guide a robot through a tape-cutting procedure in West Virginia, is slated to take place soon.

The task will be much more challenging when the target satellite is in orbit around the moon, for example. Because of the distance, there will be a significant delay between the time the operator signals the robot to move and the time these instructions are received and carried out. The research team is working on technology to help compensate for this delay.

At Johns Hopkins, the project has provided an exciting hands-on research opportunity for Jonathan Bohren, of Westchester County, N.Y., a doctoral student in mechanical engineering, and Tian Xia, of Richland, Wash., a computer science doctoral student. In the recent demonstration at Goddard, Bohren and Xia controlled the robot from a workstation at Johns Hopkins.

“The long-range goal is to be able to manipulate a space robot like this from any location to refuel satellites, for instance,” Bohren said. “A lot of satellites have the potential to have their lives extended if we can do that.”

Some satellites cost millions or even billions of dollars to construct and launch. If a cost-effective robotic rescue is possible, Xia said, then abandoning spent satellites would be wasteful. “It would be like driving a fancy car and then ditching it after it runs out of fuel,” he said. “We already have a lot of computer-assisted surgical technology here at Johns Hopkins. We could use some of it to help fix and refuel satellites.”

The principal investigator of the satellite project at Johns Hopkins is Peter Kazanzides, an associate research professor in the Department of Computer Science in the university’s Whiting School of Engineering. Kazanzides also directs the school’s Sensing, Manipulation, and Real-Time Systems (SMARTS) lab.

Color digital image of the robotic demonstration available; contact Phil Sneiderman.

Related Links:

Satellite Servicing Capabilities Office at NASA Goddard Space Flight Center:

http://ssco.gsfc.nasa.gov/about.html

Sensing, Manipulation, and Real-Time Systems (SMARTS) Lab at Johns Hopkins:

http://smarts.lcsr.jhu.edu

Computer Integrated Interventional Systems Laboratory at Johns Hopkins:

http://ciis.lcsr.jhu.edu

Dynamical Systems and Control Laboratory at Johns Hopkins

http://dscl.lcsr.jhu.edu

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Johns Hopkins University news releases can be found on the World Wide Web at http://www.jhu.edu/news_info/news/. Information on automatic E-mail delivery of science and medical news releases is available at the same address.

Large wind farms are being built around the world as a cleaner way to generate electricity, but operators are still searching for the most efficient way to arrange the massive turbines that turn moving air into power.

To help steer wind farm owners in the right direction, Charles Meneveau, a Johns Hopkins fluid mechanics and turbulence expert, working with a colleague in Belgium, has devised a new formula through which the optimal spacing for a large array of turbines can be obtained.

In wind tunnel experiments at Johns Hopkins, air currents pass through a series of small model wind turbines mounted atop posts, mimicking an array of full-size wind turbines. Photo: Will Kirk/Homewoodphoto.jhu.edu

“I believe our results are quite robust,” said Meneveau, who is the Louis Sardella Professor of Mechanical Engineering in the university’s Whiting School of Engineering. “They indicate that large wind farm operators are going to have to space their turbines farther apart.”

The newest wind farms, which can be located on land or offshore, typically use turbines with rotor diameters of about 300 feet. Currently, turbines on these large wind farms are spaced about seven rotor diameters apart. The new spacing model developed by Meneveau and Johan Meyers, an assistant professor at Katholieke Universiteit Leuven in Belgium, suggests that placing the wind turbines 15 rotor diameters apart – more than twice as far apart as in the current layouts – results in more cost-efficient power generation.

Meneveau presented the study results recently at a meeting of the American Physical Society Division of Fluid Dynamics. Meyers, co-author of the study, was unable to attend.

Charles Meneveau

The research is important because large wind farms – consisting of hundreds or even thousands of turbines – are planned or already operating in the western United States, Europe and China. “The early experience is that they are producing less power than expected,” Meneveau said. “Some of these projects are underperforming.”

Earlier computational models for large wind farm layouts were based on simply the adding up of what happens in the wakes of single wind turbines, Meneveau said. The new spacing model, he said, takes into account interaction of arrays of turbines with the entire atmospheric wind flow.

Meneveau and Meyers argue that the energy generated in a large wind farm has less to do with horizontal winds and is more dependent on the strong winds that the turbulence created by the tall turbines pulls down from higher up in the atmosphere. Using insights gleaned from high-performance computer simulations as well as from wind tunnel experiments, they determined that in the correct spacing, the turbines alter the landscape in a way that creates turbulence, which stirs the air and helps draw more powerful kinetic energy from higher altitudes.

The experiments were conducted in the Johns Hopkins wind tunnel, which uses a large fan to generate a stream of air. Before it enters the testing area, the air passes through an “active grid,” a curtain of perforated plates that rotate randomly and create turbulence so that the air moving through the tunnel more closely resembles real-life wind conditions.

Air currents in the tunnel pass through a series of small three-bladed model wind turbines mounted atop posts, mimicking an array of full-size wind turbines. Data concerning the interaction of the air currents and the model turbines is collected by using a measurement procedure called stereo particle-image-velocimetry, which requires a pair of high-resolution digital cameras, smoke and laser pulses.

Further research is needed, Meneveau said, to learn how varying temperatures can affect the generation of power on large wind farms. The Johns Hopkins professor has applied for continued funding to conduct such studies.

Related links:

Johns Hopkins video on wind turbine research: http://www.youtube.com/watch?v=U3F9qGo549k

Johns Hopkins News Release – Wind Turbines Produce ‘Green’ Energy — and Airflow Mysteries:

http://www.jhu.edu/news/home07/dec07/wind.html

National Science Foundation Feature – Lab Tests Show Wind Turbine’s Air Flow:

http://www.nsf.gov/discoveries/disc_summ.jsp?org=NSF&cntn_id=112626&preview=false

Charles Meneveau’s research page: http://www.me.jhu.edu/meneveau/

Johns Hopkins Department of Mechanical Engineering: http://www.me.jhu.edu/

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Johns Hopkins University news releases can be found on the World Wide Web at http://www.jhu.edu/news_info/news .

Information on automatic E-mail delivery of science and medical news releases is available at the same address.

Johns Hopkins Engineering for Professionals, which offers part-time education for working engineers and scientists through the university’s Whiting School of Engineering, has appointed five new chairs and a vice chair.

Applied Biomedical Engineering

• Eileen Haase, a lecturer in the Whiting School’s Department of Biomedical Engineering, has been named chair of EP’s Applied Biomedical Engineering program.

Haase received her bachelor’s degree in engineering science and mechanics from Virginia Tech in 1983. She also earned a master’s degree in electrical engineering in 1986 and a doctorate in biomedical engineering in 1991, both from Johns Hopkins. She began her career at the university’s Applied Physics Laboratory, where she was a member of the Fleet Systems Department.

• Isaac Bankman is the new vice chair of the Applied Biomedical Engineering program. Bankman is a member of the Electro-Optical Systems Group in the Air Defense Systems Department at APL and an assistant professor of biomedical engineering in the School of Medicine.

Bankman received a bachelor’s degree in electrical engineering from Bogazici University, Turkey, in 1977, a master’s in electronics from University of Wales, U.K., in 1979, and a doctorate in biomedical engineering from the Technion, Israel, in 1985.

Civil Engineering

Rachel Sangree has been appointed chair of EP’s Civil Engineering program. She is an associate research engineer and lecturer in the Whiting School’s Department of Civil Engineering.

Sangree received her bachelor’s and master’s degrees in civil engineering in 1998 and 1999 from Bucknell University and a doctorate in civil engineering from Johns Hopkins in 2006. Before starting her graduate studies, she worked for three years as a design engineer with the bridge design group at Whitman, Requardt and Associates in Baltimore and earned her professional engineering license in 2002.

Computer Science, Information Assurance and Information Systems Engineering

Thomas Longstaff, chief scientist of the Mission Assurance Branch in the Applied Information Science Department at APL, is the new chair of the EP’s Computer Science, Information Assurance and Information Systems Engineering programs.

Longstaff joined APL in 2007 to work on behalf of the federal government on a wide variety of projects involving technology transition of cyber research and development, information assurance, intelligence and global information networks.

He received his bachelor’s degree in physics and mathematics from Boston University in 1983 and his doctorate in 1992 from the University of California, Davis, in software environments.

Electrical and Computer Engineering

Brian Jennison has been appointed chair of EP’s Electrical and Computer Engineering program. A member of the principal professional staff at APL, Jennison is assistant supervisor of the Systems Group in the National Security Technology Department. He has been with APL since 1990 and has contributed to projects in underwater acoustics, radar and chemical detection for facility protection.

Jennison received a bachelor’s degree in electrical engineering from the University of Missouri, Rolla, in 1986 and a doctorate in the same discipline from Purdue University in 1990. He has been a member of the EP faculty since 1992 and had been vice chair of the Electrical and Computer Engineering program since 2007.

Mechanical Engineering

Lester Su is the new chair of EP’s Mechanical Engineering program. He is an associate research professor in the Whiting School’s Department of Mechanical Engineering and has research interests in experimental fluid mechanics, turbulent mixing and combustion, laser diagnostics, combustion systems, interaction of experiments and simulations, and spray and droplet dynamics.

Su received a bachelor’s degree in physics from the University of Chicago in 1990 and then three degrees from the University of Michigan: a master’s in aerospace engineering in 1991, a master’s in applied mathematics in 1994 and a doctorate in aerospace engineering in 1995.

Part of the Johns Hopkins University’s Whiting School of Engineering, Engineering for Professionals offers master’s degrees in 15 distinct disciplines. There are currently more than 2,300 students enrolled in EP programs at eight education centers throughout the Baltimore/Washington area and online. For more information on EP programs and functions, call 410-516-2300, visit http://ep.jhu.edu/ or send e-mail to jhep@jhu.edu .

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Johns Hopkins University news releases can be found on the World Wide Web at http://www.jhu.edu/news_info/news . Information on automatic e-mail delivery of science and medical news releases is available at the same address.

November 30, 2010
FOR IMMEDIATE RELEASE
MEDIA CONTACT: Phil Sneiderman
(443) 287-9960
prs@jhu.edu

WHEN: 1:30 to 2:20 p.m. on Wednesday, Dec. 1, 2010.

WHERE: In the lobby outside the auditorium (room B17) in the basement of Hackerman Hall on The Johns Hopkins University’s Homewood campus, 3400 N. Charles St., Baltimore, Md.

WHO: 18 three-member teams of Johns Hopkins students in a freshman mechanical engineering course will compete in a series of races to deliver a “payload” past obstacles and across a finish line.

WHAT: Each student team was required to design a device powered only by the energy stored in two mousetraps and six rubber bands provided by the instructor. Each device must proceed along an 8-foot-long course, avoiding two barriers as it moves toward the finish line. The device must carry or hurl its payload—an object the size of a credit card—past the finish line. Along the way, the carrier device can shed parts of itself, like a rocket leaving its booster sections behind. In a series of races along two parallel courses, student devices will compete to be first to get their payload across the finish line. Accuracy and speed are required to win.

WHY: While working on their projects, students have been learning about design approaches, potential and kinetic energy, friction, prototyping methods and other topics relevant to mechanical engineering.

FACULTY SUPERVISOR FOR THE EVENT: Allison Okamura, professor of mechanical engineering in Johns Hopkins’ Whiting School of Engineering.

More information about the design project and competition rules can be found at this Web site: https://haptics.lcsr.jhu.edu/wiki/images/b/b3/Freshman_project_fall10.pdf

A video about a previous Johns Hopkins mousetrap and rubber band design competition can be viewed here: http://www.youtube.com/watch?v=Y3DhgSXha-M

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Johns Hopkins University news releases can be found on the World Wide Web at http://www.jhu.edu/news_info/news/ . Information on automatic E-mail delivery of science and medical news releases

Johns Hopkins researchers have discovered that, under the right conditions, newly developed nanocrystalline materials exhibit surprising activity in the tiny spaces between the geometric clusters of atoms called nanocrystals, from which they are made.

This finding, detailed recently in the journal Science, is important because these nanomaterials are becoming more ubiquitous in the fabrication of microdevices and integrated circuits. Movement in the atomic realm can affect the mechanical properties of these futuristic materials—making them more flexible and less brittle—and may alter the material’s lifespan.

“As we make smaller and smaller devices, we’ve been using more nanocrystalline materials that have much smaller crystallites—what materials scientists call grains—and are believed to be much stronger,” said Kevin Hemker, professor and chair of Mechanical Engineering in Johns Hopkins’ Whiting School of Engineering and senior author of the Science article. “But we have to understand more about how these new types of metal and ceramic components behave, compared to traditional materials. How do we predict their reliability? How might these materials deform when they are subjected to stress?”

Kevin Hemker, seated between models representing how atoms are packed within an individual grain in a material, holds a silicon wafer onto which nanocrystalline aluminum thin film specimens have been deposited. Photo: Will Kirk/Homewoodphoto.jhu.edu

The experiments conducted by a former undergraduate research assistant and supervised by Hemker focused on what happens in regions called grain boundaries. A grain or crystallite is a tiny cluster of atoms arranged in an orderly three-dimensional pattern. The irregular space or interface between two grains with different geometric orientations is called the grain boundary. Grain boundaries can contribute to a material’s strength and help it resist plastic deformation, a permanent change of shape. Nanomaterials are believed to be stronger than traditional metals and ceramics because they possess smaller grains and, as a result, have more grain boundaries.

Most scientists have been taught that these grain boundaries do not move, a characteristic that helps the material resist deformation. But when Hemker and his colleagues performed experiments on nanocrystalline aluminum thin films, applying a type of force called shear stress, they found an unexpected result. “We saw that the grains had grown bigger, which can only occur if the boundaries move,” he said, “and the most surprising part of our observation was that it was shear stress that had caused the boundaries to move.”

“The original view,” Hemker said, “was that these boundaries were like the walls inside of a house. The walls and the rooms they create don’t change size; the only activity is by people moving around inside the room. But our experiments showed that in these nanomaterials, when you apply a particular type of force, the rooms do change size because the walls actually move.”

The discovery has implications for those who use thin films and other nanomaterials to make integrated circuits and microelectromechanical systems, commonly called MEMS. The boundary movement shown by Hemker and his colleagues means that the nanomaterials used in these products likely possess more plasticity, higher reliability and less brittleness, but also reduced strength.

“As we move toward making things at much smaller sizes, we need to take into account how activity at the atomic level affects the mechanical properties of the material,” Hemker said. “This knowledge can help the microdevice makers decide on the proper size for their components and can lead to better predictions about how long their products will last.”

The journal article describing this discovery was inspired by a Johns Hopkins master’s thesis produced by Tim Rupert, then a combined bachelor’s/master’s degree student in mechanical engineering. Rupert, who is now a doctoral student at MIT, is lead author of the Science piece. Along with Hemker, the co-authors are Daniel Gianola, a former doctoral student and postdoctoral fellow in Hemker’s lab who is now an assistant professor of materials science and engineering at the University of Pennsylvania; and Y. Gan of the Karlsruhe Institute of Technology in Germany.

Funding for the research was provided by the U.S. Department of Energy and the National Science Foundation.

Digital color photo of the Kevin Hemker available; contact Phil Sneiderman.

Related links:

Kevin Hemker’s Lab Page: http://www.me.jhu.edu/hemker/MicroNano/index.html

Johns Hopkins Department of Mechanical Engineering: http://www.me.jhu.edu/

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Johns Hopkins University news releases can be found on the World Wide Web at http://www.jhu.edu/news_info/news . Information on automatic E-mail delivery of science and medical news releases is available at the same address.