Better droplet condensation could boost power efficiency

Researchers at MIT have developed an innovative approach to improving heat transfer in power plants and cooling systems. The new system could provide a 100 percent improvement in the efficiency of heat transfer over conventional systems, the researchers say.

Heat transfer by condensation is key to the operation of today’s power plants, where fossil fuels are used to boil water and the resulting steam drives turbines to generate electricity. The steam must then condense back to water, which is collected and sent back to the boiler to start the cycle again.
The new system is an improvement of the condensers used to turn steam back into water. The same principle might also be used to improve condensers in desalination plants and in thermal-management systems.
Three key qualities contribute to the efficiency of heat transfer in such systems: Droplets must form easily and abundantly on a condenser surface; the area of contact between the droplet and the surface must be large enough to easily conduct heat; and the droplets must quickly fall away from that surface to allow new droplets to start condensing.
While most previous research on improving condensers has focused on the third part, the new work improves all three aspects at once, says associate professor of mechanical engineering Evelyn Wang, senior author of a paper just published in the journal Scientific Reports. The report was co-authored by Rong Xiao and Nenad Miljkovic, both of whom just completed their PhDs at MIT, and former postdoc Ryan Enright.
The innovation combines two properties: First, a nanopatterned surface, etched with tiny pillars, reduces contact between droplets and the surface. Second, a layer of oil coats the surface, helping droplets to form abundantly on the surface and also making it easy for them to slide off.
“We know it’s a combination of these qualities that is optimal,” Wang says. “We believe the big contribution of this work is to drastically enhance [droplet] densities. … We see [droplets] form on every single one of those pillar tops.”

Condensers’ contradictory need to enhance both droplet formation (requiring a hydrophilic surface) and droplet release (requiring a hydrophobic surface) is satisfied by the combination of nanostructures and an oily surface. This results in a surface that is locally hydrophilic — attracting droplets to the tops of the tiny pillars — while still being hydrophobic overall, causing droplets to fall away quickly as they grow in size. The new system produces much greater density of droplets than has been achieved on most other nanopatterned surfaces, Wang says.
Because the droplets condense right through the thin coating of oil, and end up being immersed in oil, the researchers coined the term “immersion condensation” to describe their new system. The new approach can be applied to ordinary copper plates or tubes, typically used in today’s condensers, so it should be relatively easy to incorporate into existing plants, Wang says.
The group initially did computer modeling of the system, then carried out experiments to verify the models’ predictions. The experiments confirmed a 100 percent enhancement of heat-transfer efficiency, compared to untreated copper surfaces.
Further research, using different kinds of oil and different texture patterns, could yield even greater improvements, Wang says. “There’s lots of opportunity for optimization of the structures to get better performance,” she says.
Anthony Jacobi, a professor of mechanical science and engineering at the University of Illinois at Urbana-Champaign, says this research “is very exciting to me, because it not only demonstrates the innovative use of surface heterogeneity to promote immersion condensation, but it carries that idea to a potentially scalable and inexpensive deployment that may be useful in real power-generation or water-recovery systems. … The impact on energy efficiency could be tremendous.”
This work was supported by the Office of Naval Research and MIT’s Solid State Solar Thermal Energy Conversion Center, which is funded by the U.S. Department of Energy.
 

Researchers use video game tech to steer roaches on autopilot

North Carolina State University researchers are using video game technology to remotely control cockroaches on autopilot, with a computer steering the cockroach through a controlled environment. The researchers are using the technology to track how roaches respond to the remote control, with the goal of developing ways that roaches on autopilot can be used to map dynamic environments – such as collapsed buildings.

The researchers have incorporated Microsoft’s motion-sensing Kinect system into an electronic interface developed at NC State that can remotely control cockroaches. The researchers plug in a digitally plotted path for the roach, and use Kinect to identify and track the insect’s progress. The program then uses the Kinect tracking data to automatically steer the roach along the desired path.

The program also uses Kinect to collect data on how the roaches respond to the electrical impulses from the remote-control interface. This data will help the researchers fine-tune the steering parameters needed to control the roaches more precisely.
“Our goal is to be able to guide these roaches as efficiently as possible, and our work with Kinect is helping us do that,” says Dr. Alper Bozkurt, an assistant professor of electrical and computer engineering at NC State and co-author of a paper on the work.
“We want to build on this program, incorporating mapping and radio frequency techniques that will allow us to use a small group of cockroaches to explore and map disaster sites,” Bozkurt says. “The autopilot program would control the roaches, sending them on the most efficient routes to provide rescuers with a comprehensive view of the situation.”
The roaches would also be equipped with sensors, such as microphones, to detect survivors in collapsed buildings or other disaster areas. “We may even be able to attach small speakers, which would allow rescuers to communicate with anyone who is trapped,” Bozkurt says.
Bozkurt’s team had previously developed the technology that would allow users to steer technology remotely, but the use of Kinect to develop an autopilot program and track the precise response of roaches to electrical impulses is new.
The interface that controls the roach is wired to the roach’s antennae and cerci. The cerci are sensory organs on the roach’s abdomen, which are normally used to detect movement in the air that could indicate a predator is approaching – causing the roach to scurry away. But the researchers use the wires attached to the cerci to spur the roach into motion. The wires attached to the antennae send small charges that trick the roach into thinking the antennae are in contact with a barrier and steering them in the opposite direction.

 

Video Games an Effective Tool for Stroke Rehabilitation

In the months following a stroke, patients undergo hours of rehabilitation to restore movement, speech, and overall functionality. But many still return home without the ability to perform daily tasks, such as dressing, cooking or driving.

Now occupational therapist Dr. Debbie Rand of Tel Aviv University’s Stanley Steyer School of Health Professions at the Sackler Faculty of Medicine, has turned to common interactive video games as an affordable and effective alternative to traditional therapy. In a recent study, done in collaboration with a team from Sheba Medical Center and funded by the Marie Curie International Reintegration Grant, she found that people recovering from stroke who use video games as a therapeutic method are more physically active during rehabilitation sessions, making more movements overall than those who experience traditional motor therapy.
The results were presented at the 9th International Conference on Disability, Virtual Reality and Associated Technologies (ICDVRAT 2012).
Goal-directed movement
Interactive game consoles require players to move continuously to interact with the virtual games, Dr. Rand explains. In her study, not only did the players perform double the number of arm movements during each session compared to patients in traditional therapy, but all of their movements were purposeful or “goal-directed” and not just repetitive exercises.
When individuals plan their movements and move deliberately in order to accomplish a specific goal, it is likely to have a positive impact on brain plasticity — changes in the brain that are crucial for recovery from brain damage caused by stroke, Dr. Rand notes. Players’ movements require precision and balance, and there is a cognitive benefit in that video games require strategy and planning. And because the individuals are motivated and enjoy the activity, it’s more likely that they will continue the treatment regime long-term, she believes.
To test the effectiveness of interactive video games compared to traditional therapy, individuals who had experienced a stroke one to seven years before the study began were randomly assigned to one of two groups of 20 participants each — a traditional therapy group, who completed traditional rehabilitation exercises, and a video games group which played video games using Xbox Kinect, Sony PlayStation and Nintendo Wii gaming consoles. Each group received two sessions a week with occupational therapists for a period of three months.
Although both groups showed improvement in functions such as grip strength of their weaker and stronger hands and gait speed, participants in the video games group continued to improve their grip strength for three months following the intervention, while the traditional group did not.
Having fun with therapy
Beyond the physical advantages, Dr. Rand believes that video games could be an excellent alternative to traditional therapy simply because they’re more fun. In the video game group, 92 percent of participants reported enjoying the experience “extremely” or “very much,” opposed to 72 percent of the traditional group. If patients are enjoying the therapy experience, it’s more likely that they will adhere to the therapy regime long-term, noting that game consoles are now widely available and fairly inexpensive. Participants who were in the video game playing group reported: “It was lots of fun,” “it stimulated all of my senses,” and “I finished the sessions wet from sweat, which proves that I really worked hard.”
The group environment also contributed to the success of the therapy, Dr. Rand says. Often, individuals with stroke are isolated and don’t have a very active social life. This program allowed them to connect with people like themselves, and encourage and support one another’s efforts.
In future studies, she intends to investigate whether these interactive video games will be as effective if they are used independently by patients at home to keep up activity levels — a crucial element of rehabilitation following a stroke.

Dear Internet Don’t Do This

And you too, computer, now that I think of it. I have a list here of things that are annoying that are similar to each other in that they interfere with my most basic use of the computer. Most of the time I demand very little of a computer. Writing text in a text editor or in the text boxes of web pages, and reading things. That is mostly what I do. It is astonishing that in 2012 when we are about to do this that these simple tasks can be thwarted by poor design and engineering in the software running on what is really pretty advanced hardware.

1) Reloading web pages. This is best exemplified with our local CBS affiliate, WCCO, news site. Let’s say I open up a web page that has an interesting news story. I read part of the page and then I get distracted by something shiny for, say, 20 seconds, then I go back to finish reading the story and the page reloads. I’m now back to the top of the page. I work my way down the text to find where I left off, and start reading again. Then, I get to the end of the page and I’m about to read the last sentence, and the page reloads. Or, worse, I start up one of the embedded videos on the page. And while the video is still playing, the page reloads. Why does this page keep reloading? How can you make a news site that reloads pages while the reader is reading them almost every time if the story is longish, or, amazingly, if the reader is watching a video? Why?

I’ve actually emailed WCCO about this. This problem has been going on for at least a year, and I’m sure others have complained as well. Haven’t they? I guess there is no internal mechanism at CBS or WCCO for problems with the user eperience to translate into a redesign of the technology.

2) Moving text boxes. This is a BIG problem with Google+ but it also happens in Facebook. You have a text box in which you are entering a post, status update, or comment, and while you are typing this in, suddenly the pages shifts. This is like the reloading page mentioned above but with a different technology and effect. The point is, your text box is gone and now you have to find it to write that last one or two words of the brilliant thought you were just about to post which you may have lost track of because of this distraction. This is like if Hemmingway was writing a novel and at random intervals somebody walked into the room and rolled the typewriter platten on him. The people who designed that technology clearly don’t use the technology.

3) Text Boxes that go on vacation. This is where you are typing text into a text box, like where you put your Facebook status, and suddenly you are typing and nothing is happening. Then, suddenly, all the text you were typing comes flying out. This actually has been known to happen to me in my text editor when it decides to take too much time saving backups and maybe something is wrong with the hard disk system. So, OK, I replaced the hard drive and fixed that, but still.

4) And another thing. Why is it that bringing up a simple file manager and having it populated with the file data takes so long? Isn’t that the most basic function of my system? Shouldn’t that happen instantaneously?

Internet and Computer Software Industry, please fix these things.

Thank you very much, that is all.

I can’t get my monitor display brightness to stay up/adjust

This is an informational post for those of you who are using Linux on a laptop and are having a hard time adjusting the display brightness. This is problem that can cause your laptop to become more or less useless, assuming you want to see the screen but the brightness is wrong (usually too low, i.e., not maximum or near maximum) so I don’t want to call it a low level problem, but it is low level in that it affects only a few people. Complaints about this problem are scattered thinly across the internet, and every person with this problem seems to have two things: 1) A different computer or system from every other person with this problem and 2) only lame answers that generally don’t work.
Well, I have a generalizable solution that should work on a wide range of configurations. This might even work on Windows computers, but who cares about them. Anyway, here it is:

How to adjust the brightness of the monitor of your laptop running Linux:

This assumes that the two usual methods are not working. Those methods are:
1) find an adjustment slider bar or something in the system configuration thingie and turn it up or down; or
2) press the blue fn key (lower left part of your keyboard somewhere) along with the appropriate brightness adjustment key (there is a pair of function keys next to each other that do this) to invoke an on-screen doohickie virtual slider bar and make it go up and down.
If those two obvious answers are not working for you, there is a third temporary method that works intermittantly on some computers but not the real answer:
3) Unplug the power supply to your computer, if it is plugged in, and see what happens. Not the power supply INSIDE your computer, silly, just the batter charger wire coming from the brick.
OK, so none of those things work which is why you are here. So, now try this method which should work. There are four steps:
i) Accept, and be happy with, the fact that your computer will have one brightness setting and you can’t change it.
ii) Go to the system settings (#1 above), and especially your Power Settings, and change everything around so that the display brightness slider switch is where you want it (or would want it if it worked), ie., maximum, AND (this is important) disable/turn off any settings that promise to change the display settings, such as “dim screen after 20 minutes of inactivity” or “dim screen when using battery” etc. In other words, get the settings like you want them, but referring back to item i above, that will not include allowing your system to change the display brightness.
iii) Turn off your computer, turn it back on again (or “restart” if you like) and hit F2 (or another key as needed) to invoke the BIOS screen.
iv) Now that you are at the BIOS screen, you’ll notice that there is no adjustment there for this problem, but that does not matter. The thing is, the function key buttons (see #2 above) should work while you have the BIOS screen up! So, adjust the brightness to where you want it, and hit F10 or whatever to exit out of BIOS and let your computer boot.
Then, it should stay fixed. If it breaks later, repeat.