... CONTINUES.

Russell began his published work in 1896 with German Social Democracy, a study in politics that was an early indication of a lifelong interest in political and social theory. In 1896, he taught German social democracy at the London School of Economics, where he also lectured on the science of power in the autumn of 1937. He was also a member of the Coefficients dining club of social reformers set up in 1902 by the Fabian campaigners Sidney and Beatrice Webb. He now started an intensive study of the foundations of mathematics at Trinity during which he discovered Russell's paradox which challenged the foundations of set theory. In 1903 he published his first important book on mathematical logic, The Principles of Mathematics showing that mathematics could be deduced from a very small number of principles, and contributing significantly to the cause of logicism.

The Idea of Righteousness

The third psychological impulse which is embodied in religion is that which has led to the conception of righteousness. I am aware that many freethinkers treat this conception with great respect and hold that it should be preserved in spite of the decay of dogmatic religion. I cannot agree with them on this point. The psychological analysis of the idea of righteousness seems to me to show that it is rooted in undesirable passions and ought not to be strengthened by the imprimatur of reason. Righteousness and unrighteousness must be taken together; it is impossible to stress the one without stressing the other also. Now, what is "unrighteousness" in practise? It is in practise behaviour of a kind disliked by the herd. By calling it unrighteousness, and by arranging an elaborate system of ethics around this conception, the herd justifies itself in wreaking punishment upon the objects of its own dislike, while at the same time, since the herd is righteous by definition, it enhances its own self-esteem at the very moment when it lets loose its impulse to cruelty. This is the psychology of lynching, and of the other ways in which criminals are punished. The essence of the conception of righteousness, therefore, is to afford an outlet for sadism by cloaking cruelty as justice.

But, it will be said, the account you have been giving of righteousness is wholly inapplicable to the Hebrew prophets, who, after all, on your own showing, invented the idea. There is truth in this: righteousness in the mouths of the Hebrew prophets meant what was approved by them and Yahweh. One finds the same attitude expressed in the Acts of the Apostles, where the Apostles began a pronouncement with the words "For it seemed good to the Holy Ghost, and to us" (Acts xv, 28). This kind of individual certainty as to God's tastes and opinions cannot, however, be made the basis of any institution. That has always been the difficulty with which Protestantism has had to contend: a new prophet could maintain that his revelation was more authentic than those of his predecessors, and there was nothing in the general outlook of Protestantism to show that this claim was invalid. Consequently Protestantism split into innumerable sects, which weakened one another; and there is reason to suppose that a hundred years hence Catholicism will be the only effective representation of the Christian faith. In the Catholic Church inspiration such as the prophets enjoyed has its place; but it is recognized that phenomena which look rather like genuine divine inspiration may be inspired by the Devil, and it is the business of the church to discriminate, just as it is the business of the art connoisseur to know a genuine Leonardo from a forgery. In this way revelation becomes institutionalized at the same time. Righteousness is what the church approves, and unrighteousness is what it disapproves. Thus the effective part of the conception of righteousness is a justification of herd antipathy.

It would seem, therefore, that the three human impulses embodied in religion are fear, conceit, and hatred. The purpose of religion, one may say, is to give an air of respectability to these passions, provided they run in certain channels. It is because these passions make, on the whole, for human misery that religion is a force for evil, since it permits men to indulge these passions without restraint, where but for its sanction they might, at least to a certain degree, control them.

I can imagine at this point an objection, not likely to be urged perhaps by most orthodox believers but nevertheless worthy to be examined. Hatred and fear, it may be said, are essential human characteristics; mankind always has felt them and always will. The best that you can do with them, I may be told, is to direct them into certain channels in which they are less harmful than they would be in certain other channels. A Christian theologian might say that their treatment by the church in analogous to its treatment of the sex impulse, which it deplores. It attempts to render concupiscence innocuous by confining it within the bounds of matrimony. So, it may be said, if mankind must inevitably feel hatred, it is better to direct this hatred against those who are really harmful, and this is precisely what the church does by its conception of righteousness.

To this contention there are two replies -- one comparatively superficial; the other going to the root of the matter. The superficial reply is that the church's conception of righteousness is not the best possible; the fundamental reply is that hatred and fear can, with our present psychological knowledge and our present industrial technique, be eliminated altogether from human life.

To take the first point first. The church's conception of righteousness is socially undesirable in various ways -- first and foremost in its depriciation of intelligence and science. This defect is inherited from the Gospels. Christ tells us to become as little children, but little children cannot understand the differential calculus, or the principles of currency, or the modern methods of combating disease. To acquire such knowledge is no part of our duty, according to the church. The church no longer contends that knowledge is in itself sinful, though it did so in its palmy days; but the acquisition of knowledge, even though not sinful, is dangerous, since it may lead to a pride of intellect, and hence to a questioning of the Christian dogma. Take, for example, two men, one of whom has stamped out yellow fever throughout some large region in the tropics but has in the course of his labors had occasional relations with women to whom he was not married; while the other has been lazy and shiftless, begetting a child a year until his wife died of exhaustion and taking so little care of his children that half of them died from preventable causes, but never indulging in illicit sexual intercourse. Every good Christian must maintain that the second of these men is more virtuous than the first. Such an attitude is, of course, superstitious and totally contrary to reason. Yet something of this absurdity is inevitable so long as avoidance of sin is thought more important than positive merit, and so long as the importance of knowledge as a help to a useful life is not recognized.

The second and more fundamental objection to the utilization of fear and hatred practised by the church is that these emotions can now be almost wholly eliminated from human nature by educational, economic, and political reforms. The educational reforms must be the basis, since men who feel hatred and fear will also admire these emotions and wish to perpetuate them, although this admiration and wish will probably be unconscious, as it is in the ordinary Christian. An education designed to eliminate fear is by no means difficult to create. It is only necessary to treat a child with kindness, to put him in an environment where initiative is possible without disastrous results, and to save him from contact with adults who have irrational terrors, whether of the dark, of mice, or of social revolution. A child must also not be subject to severe punishment, or to threats, or to grave and excessive reproof. To save a child from hatred is a somewhat more elaborate business. Situations arousing jealousy must be very carefully avoided by means of scrupulous and exact justice as between different children. A child must feel himself the object of warm affection on the part of some at least of the adults with whom he has to do, and he must not be thwarted in his natural activities and curiosities except when danger to life or health is concerned. In particular, there must be no taboo on sex knowledge, or on conversation about matters which conventional people consider improper. If these simple precepts are observed from the start, the child will be fearless and friendly.

On entering adult life, however, a young person so educated will find himself or herself plunged into a world full of injustice, full of cruelty, full of preventable misery. The injustice, the cruelty, and the misery that exist in the modern world are an inheritance from the past, and their ultimate source is economic, since life-and-death competition for the means of subsistence was in former days inevitable. It is not inevitable in our age. With our present industrial technique we can, if we choose, provide a tolerable subsistence for everybody. We could also secure that the world's population should be stationary if we were not prevented by the political influence of churches which prefer war, pestilence, and famine to contraception. The knowledge exists by which universal happiness can be secured; the chief obstacle to its utilization for that purpose is the teaching of religion. Religion prevents our children from having a rational education; religion prevents us from removing the fundamental causes of war; religion prevents us from teaching the ethic of scientific co-operation in place of the old fierce doctrines of sin and punishment. It is possible that mankind is on the threshold of a golden age; but, if so, it will be necessary first to slay the dragon that guards the door, and this dragon is religion.

THE END.

His synergetic design is a floating permaculture, comprised of many green systems including wind power. Made possible by a grant from the Bakema Foundation and partnering with the Netherlands Architecture Institute and A10, Koering’s system is radical, futuristic, and would float about the North Sea.

Floating Permaculture offers a solution to the inevitable depletion of fossil fuels and its effect on food. “Normal” farming as we know it puts a strain on fossil fuels, as produce is often trucked hundreds of miles to consumers, which contributes to traffic, air pollution and carbon emissions. Koering feels that recent alternative methods, like rooftop farming, will still not be enough to sustain the population, as not every roof can support a farm or produce enough food.

The idea of a permaculture loop originates from the Aztecs, who sought to create self-sufficient farm systems. The multilayered floating farms draw energy from alternative resources, outfitted with solar receivers, wind turbines and wave turbines. Wastewater and rain water are filtered naturally, through either an algae farm and subsequent reactor, or through a filter system using zebra mussels, and then re-circulated to nourish the organic produce. The zebra mussels also provide nourishment for fish and chickens which are raised on the mass. The excrement from the fish and other animals is used to fertilize the rice paddies, which in turn feed the chickens – as does the excess algae from the water purification system. Each feeds the next.

One problem of this idealistic system is that the current technology that harvests wind and sun energy cannot maintain or store enough energy to sustain the permacultures. A hydrogen-fuel cell can help generate the necessary energy, which can then be stored in a hydro-electric power-plant.

This fantastical floating utopia may seem like a science fiction movie from the 1960s now, but could be a viable option in the future if our natural resources do in fact run out. Complex self-sufficient and looped systems may be the answer to food production if traditional farming is no longer an option.

Source: Inhabitat.com

Scientists at the University of Illinois (U of I) believe they've stumbled upon a breakthrough that could eventually lead to the development of a lithium-ion battery that, much like some parts of the human body, actually heals itself. The researchers took an in-depth look at rechargeable li-ion batteries used in everyday items – cellphones, laptop computers and digital cameras – and discovered that those batteries tend to degrade over time.

Scott White, a University of Illinois materials engineer, stated, "There are many different types of degradation that happen, and fixing this degradation could help us make longer-lasting batteries." White claims that a battery's anode, which swells while charging and then shrinks during the discharge cycle, can eventually crack and that, in due time, is what can lead to a battery's demise.

After extensive testing, the U of I scientists discovered that by embedding tiny self-healing polymers that tear open and release indium gallium arsenide (a liquid metal alloy) the microscopic cracks in the anode could be filled in, thus rejuvenating the battery and potentially extending its useful life.

Source: Autoblog Green

The last time an ocean submersible took a crew down to Challenger Deep, the deepest known point in the Mariana Trench (about 36,000 feet below the surface), it was 1960. Now, submersible designers Triton Submarines aims to take humans down to Challenger Deep again using their newly designed submersible Triton 36,000.

The Triton 1000 Modeled after earlier iterations of Triton's submersibles, the borosilicate glass dome of the Triton 36,000 will be able to withstand far greater pressures. Triton Submarines.

This is something of a technological leap for Triton. Its current submersibles are mostly designed for scientists and yacht owners and only dive to depths of about 3,300 feet. To move its maximum depth by an order of magnitude Triton enlisted the help of Rayotek Scientific, who redesigned the company’s domed passenger compartment with a novel new kind of material.

Triton 36,000, in Profile:  Triton Submarines.

This borosilicate glass gets stronger under compression, so the deeper you take the submersible, the stronger the glass gets. Up to a point, of course. Before Triton 36,000 attempts to take a crew of three down to the deepest point in the oceans, it will have to undergo testing at pressures at least one and a quarter times the pressure at Challenger Deep.

Source: PopSci

Four theoretical physicists, led by Allan Widom, of Northeastern University, have published a paper in arXiv, where they show a possible way for some bacteria to produce radio waves. Taking note of the fact that bacteria DNA forms in loops rather than the familiar helix seen in humans, Widom, et al, describe a process whereby free electrons that flow through such a loop by hopping from atom to atom, wind up producing photons when energy levels change.

While the paper hasn’t whipped up nearly as much controversy as happened when French virologist Luc Montagnier, (Nobel Prize winner for linking HIV and AIDS) first suggested back in 2009 that bacteria might be able to communicate with one another via radio waves, it has nonetheless sparked tremendous debate among biologists and other scientists in the field. The problem has been that Montagnier showed that when compared to pure water, samples chockfull of bacteria, emitted more radio waves, and no one could explain why.

Low-temperature electron micrograph of a cluster of E. coli bacteria, magnified 10,000 times. Each individual bacterium is oblong shaped. Photo by Eric Erbe, digital colorization by Christopher Pooley, both of USDA, ARS, EMU.

Researchers have known for years that some bacteria do communicate via nanowires, which led Widom and his team to conclude that it wasn’t so farfetched to believe more highly developed bacteria, such as E. coli or Mycoplasma pirum, might instead communicate via wireless medium.
Basing their findings on modeling, Widom and his team, calculated that the transition frequencies broadcast (0.5, 1 and 1.5 kHz) when free electrons traversed bacterial DNA loops and met with differing energy levels, corresponded with just the amount of signal emission found in the E. coli bacterial studies by Montagnier.

The problem here of course is that while the model does suggest that certain bacteria might be capable of producing radio waves, it doesn’t go anywhere towards proving that such radio waves are actually used as a means of communication, either by the sender bacterium, or another receiver. There’s no research thus far that shows any sort response to such radio waves or any sort of “message” that might be encoded in such missives; hence the current controversy about what to make of bacteria that can produce radio waves.

It’s likely these new findings will incite others to look a little deeper, however, as the main argument for rejecting Montagnier’s findings back in 2009, was that bacteria lacked a means for generating radio signals; an assertion that has now been overthrown.

Source: PhysOrg

The device, called GraVVITAS, is a standard tablet PC with touch screen technology that uses vibration and sounds to guide the visually impaired user around a diagram.

It is designed to enable the user to build a picture of the entire graphic in their mind.

Currently, visually impaired students are using tactile diagrams to understand graphics. These raised shapes and textures are produced on a particular type of paper by special purpose printers, known as embossers. This method can prove to be extremely costly and can take months to produce a textbook.

The Faculty of Information and Technology’s Professor Kim Marriott and PhD student Cagatay Goncu are working with Vision Australia to develop the new technology, that will make accessing diagrams for visually impaired students easier.

“The idea stemmed from a visually impaired student that I had years ago in a unit that was very diagrammatic,” Professor Marriott said.

“This particular student had major problems understanding the diagrams using the methods that were available to them at the time. We wanted to try to increase accessibility to diagrams and graphics in educational material, which is a huge issue for the visually impaired.”

Dr. Marriot and Mr Goncu testing out a prototype of the GraVVITAS

The device, which is currently a prototype, has small external vibrating motors that attach to the user’s fingers. These motors buzz when an object displayed on the screen is touched.

Cagatay Goncu said voice prompts and sounds also help to guide the user to read the diagram.

“The basic idea is to guide the user to find the object by using sound. Touching the object causes the sound to stop and a voice explains what that object is and any other information associated with it,” Mr. Goncu said.

“If it’s something on the left side, you will hear something in your left ear and vice-versa.”

Developing the technology has involved extensive testing with visually impaired volunteers, which has allowed researchers to have a better understanding of how they read diagrams.

The next stage of development will involve collaborating with haptic feedback specialists from the Faculty of Engineering who will further refine the touch technology associated with the device.

Source: physorg - Provided by Monash University

Monkeys are being trained to control what might be the world's most sophisticated and human-like robot arm. But they never touch the prosthetic limb or fiddle with a remote control: they guide it with their thoughts alone. If trials are successful, in a few months from now people with spinal cord injuries could learn to do the same.

In 2008, Andrew Schwartz of the University of Pittsburgh in Pennsylvania published a landmark paper describing how two rhesus macaques learned to feed themselves marshmallows and fruit using a crude robotic limb controlled by electrodes implanted in their brains (Nature, DOI: 10.1038/nature06996). No brain-controlled prosthetic limb had ever carried out a more complex real-world task. Still, Schwartz envisioned a more elegant and nimble device that paralysed people could use - something much closer to a human hand.

Enter the Modular Prosthetic Limb (MPL), a bionic limb that closely approximates the form and agility of a human arm and hand. Born from the US Defense Advanced Research Projects Agency's Revolutionizing Prosthetics programme, and designed by Michael McLoughlin's team at the Johns Hopkins University Applied Physics Laboratory in Maryland, the MPL is made from a combination of lightweight carbon fibre and high-strength alloys. It has 22 degrees of freedom, compared with the human arm's 30, and can grasp precisely and firmly without crushing fragile objects. The wrist and elbow rotate with ease and, like an average human limb, it weighs just under 4.5 kilograms.

"I would say it's very close to human dexterity," says McLoughlin. "It can't do absolutely everything - it can't cup the palm, for example - but it can control all fingers individually. I don't think there is another limb that approaches it."

A prototype of the MPL has been tested by people who have had one or both arms amputated. Researchers surgically redirect nerves that would normally control the arm into unused chest muscle, where nerve signals are interpreted by electrodes that guide the robotic limb. "One of our patients, Jesse Sullivan, was able to use the arm almost from time zero. It was a very natural thing to do," says McLoughlin. "The brain still thinks the arm is there and if you can tap into those signals, you can really achieve something amazing."

But people paralysed from the neck down cannot benefit from this technique as brain signals cannot reach the chest. So in his work with rhesus macaques, Schwartz developed an array of 100 electrodes that eavesdrops on 100 neurons in the motor cortex. Once he had learned the electrical language the cortex uses to guide arm movement, he converted those signals into instructions for a crude robotic limb with a two-finger clamp. Now Schwartz is training his monkeys again, except this time he wants to teach them to use the five-fingered MPL and perform the kind of everyday but complex tasks we take for granted.

If the monkeys demonstrate that it is possible to steer the arm with brainpower alone, Schwartz and colleagues will give people with spinal cord injuries a chance to try the MPL. "For someone with spinal cord injury, it's a huge deal for them to be able to feed themselves," says McLoughlin. "Nobody has achieved this level of a control in humans with a brain-controlled prosthetic. We want to take it to a higher level than in the past."

Source: NewScientist

Imagine a swarm of microrobots—tiny devices a few hair widths across—swimming through your blood vessels and repairing damage, or zipping around in computer chips as a security lock, or quickly knitting together heart tissue. Researchers at the University of California, Berkeley, Dartmouth College, and Duke University have shown how to use a single electrical signal to command a group of microrobots to self-assemble into  larger structures. The researchers hope to use this method to build biological tissues. But for microrobots to do anything like that, researchers must first figure out a good way to control them.

"When things are very small, they tend to stick together," says Jason Gorman, a robotics researcher in the Intelligent Systems Division at NIST who co-organizes an annual microrobotics competition that draws groups from around the world. "A lot of the locomotion methods that have been developed are focused on overcoming or leveraging this adhesion."

Tiny robots: This wafer holds many individual microrobots. Each robot consists of a body (about 100 micrometers long) and an arm that it uses to turn. Several of these robots can be controlled at once.
Credit: Igor Paprotny

So far, most control methods have involved pushing and pulling the tiny machines with magnetic fields. This approach has enabled them to zoom around on the face of a dime, pushing tiny objects or swim through blood vessels. However, these systems generally require complex setups of coils to generate the electromagnetic field or specialized components, and getting the robots to carry out a task can be difficult.

Bruce Donald, a professor of computer science and biochemistry at Duke, took a different approach, developing a microrobot that responds to electrostatic potential and is powered with voltage through an electric-array surface. Now he and others have demonstrated that they are able to control a group of these microrobots to create large shapes. They do this by tweaking the design of each robot a little so that each one responds to portions of the voltage with a different action, resulting in complex behaviors by the swarm.

"A good analogy is that we have multiple, remote-controlled cars but only one transmitter," says Igor Paprotny, a post doctorate scientist at UC Berkeley and one of the lead researchers on this work, which he presented last week at a talk at Harvard University. During his talk, he passed around a container holding a wafer die the size of a thumbnail. On it were more than 100 microrobots.

"What we do is slightly change how the wheels turn," he says. "Simple devices with a fairly simple behavior can be engineered to behave slightly different when you apply a global control signal. That allows a very complex set of behaviors." The robots contain an actuator called a scratch drive, which bends in response to voltage supplied through the electric array. When it releases tension, it goes forward, in a movement similar to an inchworm's. But the key to the robots' varying behavior is the arms extending from the actuators. A steering arm on a microrobot snaps down in response to a certain amount of voltage, dragging on the surface and causing the robot to turn. By snapping the arm up and down one or two times a second, the team can control how much a given robot turns. To control a swarm, the team designed each robot with an arm that reacts differently during portions of the voltage signal. Computer algorithms vary the voltage sequence, prompting the robots to move in complex ways.

"Electrostatic robots have an advantage in that their power is supplied through an electrode array that the microrobots sit on," says Gorman. "It can be very compact. Therefore, electrostatic microrobots can be embedded inside other things [like computer chips]. For magnetic robots, you have to supply electromagnetic field, and that requires a larger set-up." Others have worked on electrostatic microrobots, he adds, but this work is the furthest along.

"His research is very advanced in terms of controlling multiple microrobots," says Zoltan Nagy, a roboticist at ETH Zürich who works with groups of magnetically controlled robots called Magmites.

"Most of the work to date has been on controlling a single robot that can move around in a pre-defined area on a substrate," adds Gorman. "However, many of the applications of interest will require control of lots of robots, like a colony of ants."

So far, Paprotny has been able to control up to four robots on a single surface at once, and the robots can move several thousand times their body length per second, as detailed in a paper that is currently submitted for review. His next plan is to adapt the setup for a liquid environment so that the microrobots can assemble components of biological tissue into patterns that mimic nature.

"We're trying to come up with ways of self-assembling tissue units," says Ali Khademhosseini, an associate professor at Brigham and Women's Hospital at Harvard Medical School and a specialist in tissue engineering who is collaborating with Paprotny. "In the body, tissues are made in a hierarchical way—units repeat themselves over and over to generate larger tissue structures." Muscle tissue, for example, is made from small fibers, while liver tissue has a repeating hexagonal shape.

Khademhosseini has encased cells in jelly-like hydrogels and assembled them (using methods that include liquid-air interactions and surface tensions) into different regions to mimic biological tissues. But he thinks the self-assembling microrobots will allow more control in creating the tissues.

"We can try to combine cells and materials in microfabrication systems to come up with structures and assemble them in particular ways using the techniques Igor has developed," says Khademhosseini.

He envisions fabricating the gels and cells on top of teams of robots working in parallel to construct different parts of a tissue. "We could use the robots to do assembly," he says. "The cells, once they're assembled, come off from the robots, letting cells rearrange further to make things that are indistinguishable from natural tissue." Initially, he hopes to create small patches of heart tissues, and then things like heart muscles and valves, and assemble them all together in a heart. "That's where things are heading," he says. "But right now the challenge is we're still not very good at making each of these individual components."

Source: TechnologyReview

The calculation would have taken a single computer processor unit (CPU) 1,500 years to calculate, but scientists from IBM and the University of Newcastle managed to complete this work in just a few months on IBM's "BlueGene/P" supercomputer, which is designed to run continuously at one quadrillion calculations per second.

Their work was based on a mathematical formula discovered a decade ago in part by the Department of Energy's David H. Bailey, the Chief Technologist of the Computational Research Department at the Lawrence Berkeley National Laboratory. The Australian team took Bailey’s program, which ran on a single PC processor, and made it run faster and in parallel on thousands of independent processors.

David H. Bailey Photo courtesy of Lawrence Berkely National Lab

"What is interesting in these computations is that until just a few years ago, it was widely believed that such mathematical objects were forever beyond the reach of human reasoning or machine computation," Bailey said.  
 
"Once again we see the utter futility in placing limits on human ingenuity and technology."
 
A binary digit or "bit" is the “DNA” of all computing. In a computer, everything is represented as strings of zeroes and ones. The decimal number 12, for instance, is represented as "1100," and the fraction 9/16 is represented as “0.1001.”  So as one might imagine, calculating the sixty-trillionth binary digit of a number is quite a feat.
 
According to Professor Jonathan Borwein of the University of Newcastle, this work represents the largest single computation done for any mathematical object to date. The idea for this project sparked when IBM Australia was looking for something to do related to "Pi Day" (March 14) on a new IBM BlueGene/P computer system. Borwein proposed running Bailey’s formula for Pi-squared, as the calculation had been done for Pi itself. The team also calculated Catalan’s constant, another important number that arises in mathematics.
 
Why Pi?

The importance of Pi has long been known -- multiply it by the diameter of any circle to get the circumference. Ancient Egyptians used this number in their design of the pyramids, meanwhile ancient scholars in Jerusalem, India, Babylon, Greece and China used this proportions in their studies of architecture and symbols.
 
Yet despite its longevity, Pi is one of the most mysterious numbers in mathematics. Because it is "irrational," Pi can never be expressed as a finite decimal number and humanity will never have anything but approximations of it. So why bother solving Pi to the ten trillionth decimal unit? After all, a value of Pi to 40 digits would be more than enough to compute the circumference of the Milky Way galaxy to an error less than the size of a proton.
 
According to Bailey, one application for computing the digits of Pi is to test the integrity of computer hardware and software, which is a focus of Bailey’s research at Berkeley Lab. “If two separate computations of digits of Pi, say using different algorithms, are in agreement except perhaps for a few trailing digits at the end, then almost certainly both computers performed trillions of operations flawlessly,” he says.
 
For example in 1986, a Pi-calculating program that Bailey wrote at NASA, using an algorithm due to Jonathan and Peter Borwein, detected some hardware problems in one of the original Cray-2 supercomputers that had escaped the manufacturer’s tests. Along this same line, some improved techniques for computing what is known as the fast Fourier transform on modern computer systems had their roots in efforts to accelerate computations of Pi. These improved techniques are now very widely employed in scientific and engineering applications. And of course, from a mathematical perspective it’s just plain fascinating to see the digits of Pi in action!

Source: PhysOrg

And the technique they found can change electrical conductivity by factors of well over 100, and heat conductivity by more than threefold.

“It’s a new way of changing and controlling the properties” of materials — in this case a class called percolated composite materials — by controlling their temperature, says Gang Chen, MIT’s Carl Richard Soderberg Professor of Power Engineering and director of the Pappalardo Micro and Nano Engineering Laboratories. Chen is the senior author of a paper describing the process that was published online on April 19 and will appear in a forthcoming issue ofNature Communications. The paper’s lead authors are former MIT visiting scholars Ruiting Zheng of Beijing Normal University and Jinwei Gao of South China Normal University, along with current MIT graduate student Jianjian Wang. The research was partly supported by grants from the National Science Foundation.

The system Chen and his colleagues developed could be applied to many different materials for either thermal or electrical applications. The finding is so novel, Chen says, that the researchers hope some of their peers will respond with an immediate, “I have a use for that!”

An artistic rendering of the suspension as it freezes shows graphite flakes clumping together to form a connected network (dark spiky shapes at center), as they are pushed into place by the crystals that form as the liquid hexadecane surrounding them begins to freeze. Image: Jonathan Tong

One potential use of the new system, Chen explains, is for a fuse to protect electronic circuitry. In that application, the material would conduct electricity with little resistance under normal, room-temperature conditions. But if the circuit begins to heat up, that heat would increase the material’s resistance, until at some threshold temperature it essentially blocks the flow, acting like a blown fuse. But then, instead of needing to be reset, as the circuit cools down the resistance decreases and the circuit automatically resumes its function.

Another possible application is for storing heat, such as from a solar thermal collector system, later using it to heat water or homes or to generate electricity. The system’s much-improved thermal conductivity in the solid state helps it transfer heat.

Essentially, what the researchers did was suspend tiny flakes of one material in a liquid that, like water, forms crystals as it solidifies. For their initial experiments, they used flakes of graphite suspended in liquid hexadecane, but they showed the generality of their process by demonstrating the control of conductivity in other combinations of materials as well. The liquid used in this research has a melting point close to room temperature — advantageous for operations near ambient conditions — but the principle should be applicable for high-temperature use as well.

The process works because when the liquid freezes, the pressure of its forming crystal structure pushes the floating particles into closer contact, increasing their electrical and thermal conductance. When it melts, that pressure is relieved and the conductivity goes down. In their experiments, the researchers used a suspension that contained just 0.2 percent graphite flakes by volume. Such suspensions are remarkably stable: Particles remain suspended indefinitely in the liquid, as was shown by examining a container of the mixture three months after mixing.

By selecting different fluids and different materials suspended within that liquid, the critical temperature at which the change takes place can be adjusted at will, Chen says.

“Using phase change to control the conductivity of nanocomposites is a very clever idea,” says Li Shi, a professor of mechanical engineering at the University of Texas at Austin. Shi adds that as far as he knows “this is the first report of this novel approach” to producing such a reversible system.

“I think this is a very crucial result,” says Joseph Heremans, professor of physics and of mechanical and aerospace engineering at Ohio State University. “Heat switches exist,” but involve separate parts made of different materials, whereas “here we have a system with no macroscopic moving parts,” he says. “This is excellent work.”

Source: PhysOrg