Monthly Archives: July 2014

Transfer Power Efficiently – Through Superconductors

At some point in our daily lives, almost all of us have heard of superconductors. These materials conduct electricity very well – with almost zero resistance. In comparison with normal wires carrying electricity, superconductors – because they offer no resistance – are almost loss-free. The caveat – superconductors need to be cooled to very low temperatures, making them almost impossible to operate at regular operating temperatures.

However, the situation may be about to change. Argonne National Laboratory has been researching on superconductors. Lately, scientists there have discovered that iron arsenics, a special class of superconductors, have a unique phase that has remained undiscovered so far. Using iron arsenics as a superconductor material may make it possible to harness the capabilities of energy efficient power transmission and use it in addition for a wide range of other technologies as well.

Electricity conduction is dependent on electrons, atoms and their interactions. Superconductivity occurs when these atoms and electrons behave in a special way, mostly at very low temperatures also called cryogenic temperatures.

The new discovery is about a magnetic phase of the electrons and atom interaction. This has offered significant implications over our understanding of unconventional superconductivity.

The new material is BAFe2As2 and scientists have doped 24% of the barium sites on the material with sodium. When neutrons are diffracted from a polycrystalline sample of the doped material, three different diffraction peaks are observed. These peaks vary with temperature as the magnetic and atomic structures change. In the graph, the structures are shown on the right, the blue balls represent the iron atoms and the red arrows show the direction of their magnetic moments.

Although superconductors allow electric current to flow without any resistance, they are not used for power transmission lines because they require to be cooled to cryogenic temperatures to operate efficiently. In comparison, copper wires operate at normal ambient temperatures and since they have resistance, are not loss-free. The recently discovered specific range of unconventional superconductors may soon offer better prospects.

Researchers at Argonne are trying to figure out how the new unconventional superconductor works. This knowledge might help to raise the temperature at which superconductors work, paving the way for harnessing their power for a wider range of new technologies.

In conventional metals carrying current, electrons bounce off atoms, thereby producing heat. In conventional superconductors, electrons – instead of repelling each other – pair off by binding together. This distorts the surrounding atoms, helping each other to travel through the metal. In the new type of superconductors also, the main process is still electron pair formation, but it is yet to be discovered what binds them together.

Normally superconductors have to be coaxed into allowing free flow of electricity. Although iron arsenide is normally magnetic, addition of sodium suppresses the magnetic behavior. As the material is cooled, it turns superconductive at roughly below -400 degree F, the transition temperature. Where, at room temperatures, iron atoms form a square lattice with a four-fold symmetry, at the transition temperature, this distorts to a rectangular lattice and a two-fold symmetry.

However, close to the onset of superconductivity, the new material demonstrates a phase where it returns to its four-fold symmetry. This is the phase intriguing the researchers.

What are Class D Amplifiers

The class AB type of audio amplifiers has been around for a long time, and most high quality ones are still typically class AB. Two things plague this excellently performing device – a quiescent bias current to keep the output semiconductors in their active region of operation and an operating efficiency that refuses to rise above 75%. In reality, this type of audio amplifiers operates with a compromise between frequency response, power output, low distortion and efficiency. Although special efforts and additional circuitry can improve the performance and efficiency of class AB amplifiers, it also makes the resulting audio amplifier prohibitively expensive.

To rid the audio amplifiers of their dependence on quiescent currents for biasing, the output semiconductors in a class D amplifier are switched on and off at a high rate. That allows the signal to appear at the output as chopped with respect to time. An averaging circuit transforms this chopped output back into analog form for feeding to the speakers. The result is an amplifier that has zero quiescent current requirement and efficiencies above 90%.

Class D amplifiers are also called digital amplifiers, of which there are two types. The first type is entirely digital while the second is a switching amplifier with analog control. Although both use switching power stages and exhibit high power efficiencies, the fully digital version has no feedback. The analog signal input is converted into digital using Analog to Digital converters and fed to the PWM switching output stage. However, achieving low distortion and good performance in all-digital class D amplifiers demands an extremely complex and expensive design.

In contrast, class D amplifiers with switching outputs but with analog controls are simpler to design and achieve very good performance with surprisingly simple circuitry. They can easily achieve extremely low output impedance over and beyond the audio range with equally low frequency-independent distortion levels.

Listening tests bear out the good performance shown in measurements. At low frequencies, because of low filter impedance, the bass is commanding and dynamic. Low THD and level response at 20 KHz produce transparent and neutral sound that real audiophiles admire.

With the music industry moving towards mobile gadgets as their main sound producing devices, interest in class D amplifiers is gaining momentum. With conservation of battery power at top priority, designers find the high efficiency of a class D amplifier very attractive. Fully integrated class D amplifiers that require the bare minimum components are now the norm in tablets and computers.

For example, the CX20952 is a high-definition audio codec from Conexant. It offers high-quality audio, low power consumption, two capacitor-free headphone amplifiers and a fully integrated class D amplifier. The intelligent single chip device keeps a check on the amount of power it delivers to the speakers, ensures maximum sound pressure levels and an optimal performance without allowing damage to system components.

With two headphone/line outputs, the CX20952 accepts a universal jack, while automatically detecting and configuring itself to different type of headsets. The single 3.5mm audio jack accepts various peripheral devices such as line-in, microphones, powered speakers, headsets and headphones.

Forget Keys Use Raspberry Pi Face Recognition

Now it is no longer necessary to use a key or a password to protect your treasures from prying eyes. Just teach your treasure box to recognize your face and it will open to no one except only when you are near it. The trick is to use the tiny, credit card sized, single board computer, the Raspberry Pi (RBPi) and its camera. When you are near, the camera and the RBPi recognize your face and the box unlocks itself.

The RBPi is the best-suited platform for this project, as it is very small and you can fit it almost anywhere. Additionally, all algorithms for this project are from the OpenCV computer vision library, which the RBPi is able to run. The advantage in building this project is that being an intermediate-level design, the project will teach you how to compile and install software on the RBPi.

For this project, you will need an RBPi model A or B and it should be running the Raspbian or the Occidentalis OS. You will also need Internet access when you are building the project. Additionally, you will require the RBPi camera module.

For the treasure box, you can use any type as long as it opens from the top and is big enough to hold the RBPi, and of course, your treasure. Among the other things you will require are a battery holder to hold 4x AAA batteries – this will be used to power the servo. For making the latch, you may use a wooden dowel and a few planks – these will be used to make a frame for the RBPi. A momentary push button may also be used – you can mount that on the side of the box.

As a start, you will have to make a hole on the top cover of the box for fitting the RBPi camera. You will also need a few more holes on the side of the box for the power cables and the push button. Mount a dowel in front of the box – the latch will catch this when the servo turns. You will need a small frame to support the RBPi and the latch servo. Clamp the servo to the frame using some wood scraps and machine screws. Fit the RBPi under the top cover of the box, such that the latch servo can swing down and catch the dowel to lock the box.

For the software, you will require the latest version of OpenCV. However, you will need to compile this from source, as the binary versions available are too old to be of use for face recognition. Compiling OpenCV on the RBPi will take about 5 hours.

For training the system to recognize you, you need to press the button to let the camera take a picture of your face and save the picture in the training directory. RBPi requires at least five pictures from different angles, with different lighting etc., for making a positive identification. The images form a database of the permitted faces that are allowed to open the treasure box.

Large scale electricity storage with graphene

At the National Graphene Institute, University of Manchester, researchers are trying to reduce the size and weight of batteries. For this, they are experimenting with graphene, as this will also increase the lifespan of the batteries. However, before they can start building lighter batteries, they need to understand how graphene interacts with the other chemical components within the battery, especially the electrolytes.

The new project has attracted considerable attention and many commercial partners are involved. They include Morgan Advanced Materials, Sharp and Rolls-Royce. All of them are interested in the future applications of graphene. The research project and applications has attracted over 30 companies from around the world.

Among the many experiments that researchers are conducting, one is to analyze the chemical interaction that takes place between graphene and lithium ions. The quest is to find out how quickly electrons move across graphene, the magnitude of capacitance and the amount of electrical energy that a graphene surface can hold.

The project is also focusing on super-capacitors, especially graphene based, as these tend to have high power densities and longer cycles of life compared to batteries, although their energy storage capacities are lower. However, the advantage they have is they can complement batteries and form an integrated storage solution.

For example, electric cars could use a combination of graphene batteries and super-capacitors to lighten up their load. Typically, batteries for electric cars weigh 200kg or as much as three passengers. If the weight of batteries were to be reduced, it would boost the efficiency of the vehicle and increase its driving range. Electric cares typically have a limitation of 100km, and this is a hindrance to their widespread use.

Increasing the distance the cars travel between charge points will definitely improve their popularity. However, it is still not very clear how the batteries will be able to stand up to the rigors and strains of daily driving. Like all other vehicles, electrical cars too are not driven smoothly; as drivers accelerate, the power demand on the batteries peaks. That stresses the battery and may be a potential cause for limiting its lifespan.

For testing the batteries, researchers will be subjecting prototype graphene batteries and super-capacitor combination to real world stresses that will mimic the profiles presented by different driving conditions. They will even test the batteries under driving in extreme conditions. Batteries are notorious underperformers in cold conditions; therefore, weather chamber tests will be rigorous. That will be instrumental in\ bringing out the weaknesses in the combinations.

The best part is that graphene based storage is useful not only in transport, but in the case of renewable energy sources as well. Usually, wind and solar energy are reliable, but there are times when the wind drops or clouds eclipse the sun. High capacity electrical storage will help to store electricity during periods of low generation.

Manchester is going to be home to a system consisting of a converter system and a grid-scale battery. This will be used for testing possibilities for large-scale electrical storage.

What are terrorist robots?

Increases in terrorist activities around the world are forcing the military to train their units in different ways for tackling the menace, especially for urban engagements. Marathon Robotics, an Australian company, in conjunction with the Australian Department of Defense, has revolutionized the way police and military personnel can train their personnel. They have adapted the two-wheeled gyro-stabilized Segway personal transporter and turned it into a Terrorist Robot.

Marathon fits their Terrorist Robots with a Segway transporter and target silhouettes. These form the remote controlled, wheeled robot targets for the military personnel to practice. Moving and responding like humans, these Segway robots can duck into doorways or disperse at the sound of gunfire. That provides the police and military sharpshooters a challenging and ultra-realistic training in engaging the moving enemy. Australian Special Forces units train using mock urban centers populated with the rolling robots from Marathon. Now, the US Marine Corps is looking forward to a similar live-fire training venue, fully equipped with Marathon’s Terrorist Robots.

Marathon has created the ultimate moving targets of the twenty-first century. They have done this by combining remote-controlled, armored Segway and computer gaming technology. With the lower half of the robots armor-plated, the expensive electronic innards remain safe from errant shots. The top has a replica of a human torso. During the training, clothing the torso section differently, enables distinguishing military targets from civilians or hostages from terrorists.

Marathon uses sophisticated software for controlling multiple Segway robots simultaneously. The software program allows a group of these robots to mimic a group of terrorists holding hostages or simply a squad on a patrol. Furthermore, the control part of the software allows the robots to demonstrate autonomous or intelligent behavior.

For example, the sound of a gunshot makes the robots disperse automatically, just as humans would. The robots can further be trained to seek cover behind objects or in hallways. More importantly, the robots can behave very similar to humans – stopping quickly, turning a full circle, retreating slowly or accelerating to a human pace of running. Just as people do, the Segbots also lean forward slightly as they move forward. To avoid running into obstacles or people on the move, Marathon equips their robots with laser range finders. Watch the Terrorist Robots in action below.

For the military or the police personnel, a battlefield is not the right place for on-the-job training. The Marathon smart targets thus provide a realistic method to address this fundamental gap in training. This is the first time shooters can fire live ammunition in a firefight at realistically moving targets. That provides the soldiers the optimum way of training to fight – using live ammunition against unpredictably moving targets.

Programming the robots is simple. The computer shows a map of the entire terrain and the placement of the robots. The possible routes that the robots can take are superimposed on the map. From here onwards, the Terrorist Robots are on their own, moving around autonomously, avoiding obstacles in their path and other robots, until a sudden gunshot changes their behavior.

Carberry for your car

Why do you need a Carberry for your car? Carberry forms a link between the car electronics and the tiny, inexpensive, versatile single board computer, the Raspberry Pi (RBPi). In sort, Carberry is a shield for the RBPi microcomputer and allows an enthusiast to develop end-user applications such as internet, carputing, burglar alarms, blackboxes, tracking, fleet management, data logging, vehicle diagnostics, media centers and much more.

Carberry can sit directly atop your RBPi, as it has the same form factor, and connects to the RBPi with the help of a 26-pin GPIO header, which is located on the Carberry PCB. You connect it to your car via a 22-pin Microfit connector, also on the PCB. Although the Carberry needs a 12VDC supply, it generates the 5V, 1A onboard for the RBPi and uses the ground connection from the vehicle. For managing the power flow to the RBPi, Carberry controls the 5V supply with a mosfet.

This also helps in performing a controlled shutdown, as it controls the power to the RBPi in the case of a logical shutdown. The entire combination follows automotive standards of low power consumption and normally consumes less than 3mA. Carberry communicates with the RBPi through the UART and utilizes pins 15 & 16 of the RBPi header.

Carberry provides ignition signal output at +12V, 2.5A controlling it through a mosfet. It reserves two CAN Bus lines and two GMLAN lines for parallel or series connection to the vehicular bus. On board, two channels are reserved for controlling a resistive steering wheel and this has the capability of being bypassed with a single key.

The general purpose UART operates at 5V or 3V3, as required by the user, while the two general purpose, open collector outputs can sink 500mA. There are two general purpose user-programmable LEDs and two general purpose inputs – the user can select the referencing to the ground or to 5V.

Carberry operates on a Microchip PIC32X microcontroller and provides a button and two-color LEDs for resetting and learning can bus profiles. If required, the user can send PWM signals to the RBPi for managing LIRC.

Cranberry can emulate infrared remote controls for media centers via the controls of the steering wheel, with the infrared sensor being suitable for 38 KHz. The board has an infrared LED onboard for the IR codes emission.

Other features of the Carberry are the user can develop applications under Linux that are ready for Apple MFI compatible. The on-board RTCC is capable of handling date and time along with battery wakeup and RBPi wakeup at programmed date/time.

An onboard external EEPROM comes with a unique identifier and users can utilize it for any license related to the card. Onboard accelerometer and magnetometer provide anti-theft features, blackboxing and positioning. The accelerometers and magnetometers can wake up the RBPi with their events, while the microusb device connector offers a stand-alone functionality for the shield in the future.

The user can upgrade the Carberry firmware via the RBPi and they can interface the Carberry to the RBPi via ASCII strings, similar to controlling modems with AT commands.

Making City Streetlights Smart with DALI

Big cities are changing over to LED lights for illumination of their streets. They find this to be a smart solution in terms of cost-reduction and efficiency. STMicroelectronics is taking an important next step by adopting LEDs for street illumination. They are doing this in conjunction with smart power supplies that turn the LED street lamps into intelligent devices. For example, the streetlamps reduce their brightness as the sun rises while gradually increasing their brightness with failing daylight. They also communicate with the smart grid in their effort to reduce the power consumption.

To avoid losses and manage electricity consumption smartly, STMicroelectronics is using LEDs that are dimmable and connected to smart grid systems. Microcontrollers drive the LEDs, and the system avoids the power losses commonly associated with non-optimized management of power such as with the use of incandescent bulbs and other forms of commonly utilized lights.

STMicroelectronics present their new solution in the form of a demo board based on STLUX385A, a digital power controller. Using a proprietary power conversion protocol, the controller drives a row of LEDs for the smart-lighting applications. DALI forms the core of the new STsystem for smartly driving the LED row.

DALI or the Digital Addressable Lighting Interface, is also standardized as IEC 929, and is a new interface for controlling lighting as defined by the lighting industry. The DCM or the DALI Communication Module generally implements DALI protocol. DCM is a serial communication circuit designed especially for controllable electronic ballasts – the device or circuit that provides the required starting voltage and operating current for the LEDs.

LEDs are different from CFLs and incandescent bulbs. LEDs require a supply of constant current. They start emitting light as soon as their forward electric threshold voltage is reached. Effectiveness of the illumination provided by a string of LEDs depends on the product of the current and the voltage applied to the string, and this must be stable in time.

HF fluorescent ballasts use the DSI protocol, and DALI is a step further. Unlike DSI and other 1-10V devices that address and control devices in a group, DALI can address each device separately on a segment of a data cable. Therefore, for achieving similar control functionality, DALI requires a simpler wiring topology as compared with DSI or 1-10V devices.

Devices that DALI can control include, apart from LEDs, wall switches, gateways to other protocols, motion detectors, PE cells, low-voltage transformers and HF ballasts for Fluorescent tubes. A single DALI network can address up to 64 DALI devices. When sites require more than 64, multiple separate DALI networks are established, each limited to 64 devices. DALI gateways then link these separate networks together, forming a data backbone running a high-level protocol, typically, DyNet from Dynalite.

Implementation of DALI facilitates equipment from different vendors to the integrated easily. This reduces the installation costs drastically, offering a finer granularity of control for a given price. However, DALI still does not totally remove the need for a data cable connect to fixtures. It also does not reduce the time required for programming and commissioning the lights. Additionally, unless extra equipment is used, DALI does not help to save the maximum possible amount of energy.

LED High Bay Lighting Produces 23650 Lumens

Hubbell Lighting, the pioneer in lighting innovation, has recently launched LUNABAY. This is an LED high bay lighting for the company’s high output categories, one that maintains an optimum efficiency of 95 Lumens per watt. The LUNABAY range can generate as high as 23,650 Lumens. Three levels of lighting are available in this range: 23,650 Lumens, 18,000 Lumens and 12,300 Lumens. Another aspect is the lights offer a CRI of 68 and is tagged with Uplight components. The LED high bay lighting ranges from 130W to 260W of total the system wattage. The lighting functions in an ambient environment within a temperature range of -40°C to +40°C. The lighting has an assured life of 50,000 hours at L70.

Lighting public places require specific features. It must cover the entire area uniformly as well as it has to present a pleasant ambiance. At the same time, it must also be safe and affordable. LUNABAY from Hubbell Lighting provides efficient lighting with a low-glare light and high level of durability. The places where this LED High bay lighting could be utilized are quite vast. They include multipurpose rooms in educational institutions, retail stores, gyms, light industrial facilities and all other places where it is essential to light the interior locations in an attractive and effective manner. LUNABAY provides lighting that cannot be matched for efficiency and durability by any other product currently available in the market.

The most important aspect of LUNABAY is its low glare feature of the LED light it produces. This feature is specifically patented and it remains an exclusive domain for Hubbell. Typically, conventional downlights in large areas generate glare and create a cave-like effect. The special optical system used in LUNBAY totally removes this discrepancy. It offers smoothly and evenly distributed light, which is consistent, has a low glare and a high CRI.

Another aspect to be noted is that the two refractors, 22” crystal clear and 23” aluminum possess Uplight components of 10% and 20% respectively. The LUNABAY lighting offers five color temperatures. The chimney part at the top can have a choice of seven colors matching the interiors. Apart from custom colors, users may select colors from white, red, black, forest green, dark bronze and platinum silver. LUNBAY offers multiple options, which includes control over on/off, fusing, wire guard, no light or 50% light output – leading to additional saving of energy. In emergency, LUNABAY is also compatible with 250VA Light Gear Inverters.

Hubbell Lighting is one the leading and largest producers of lighting fixtures in the USA. Their range covers the complete category of indoor and outdoor lighting products catering to residential needs, commercial lighting, institutional requirements and industrial markets. One of the special features of Hubbell Lighting is that the company has been consistent in developing new products in lighting, resulting in energy savings while at the same time remaining affordable to customers. The LUNABAY LED High bay Lighting is their latest product and is the only one to produce up to 23,650 Lumens. This new LED lighting is sure to make a significant positive impact on the market.

Raspberry Pi Pursues Ping-Pong Balls

Ping-pong balls are light and apt to bounce around a lot. Players have a hard time running after them, and when many are playing, finding a number of balls on the floor is a common sight. This was the case at the office of the 37signals at Chicago as well, until their system administrator, Will Jessop, who runs the North West Ruby User Group in Manchester, decided that enough is enough. He designed a solution for the problem with a Raspberry Pi running a robot to pick up the balls and collect them in a basket.

Raspberry Pi or RBPi is a low-cost, credit card sized single board computer with Linux as its operating system. Will designed the original version of the robot using the Custard Pi breakout. However, he changed over to MotorPiTX motor controller developed by Jason Barnett, as this was a much neater board. Will then sourced some of the parts necessary for the robot and built the others.

For example, he designed and 3D printed the motor mounts, the caterpillar track mounts, the ball basket and even a new base. In the end, he added a PiCamera mounted with a fish-eye lens. This made the whole contraption a neat little camera robot, reminding one of Wall-E.

Since the robot had to move around and pick up ping-pong balls, it needed its own power source to allow it to roam free. Will looked at the power requirements and tested its power usage while it was running all its motors. The RBPi robot had its own lifter arm fitted to the chassis and while this was controlled independently, the robot itself streamed video over wireless. Will finally opted for a lithium battery rated at 5AH, 7.4V.

For the software, Will decided to use Go. This, he found, was a great language for the RBPi, as he could use Go to create small, efficient statistically compiled binaries. Additionally, he could also fit them easily within the resource limits of the RBPi. Will runs the Go binaries alongside his gamepad library on his laptop, and these are available as a Ruby gem in C. To allow the RBPi to shutdown cleanly via the MotorPiTX, Will had also to write a power controller script.

Now that the robot was capable of roaming free on its battery, Will controlled it with an Xbox controller, with its camera feed streaming over Wi-Fi. By watching the video stream on a laptop, it was easy to let the robot pick up ping pong balls; see it in action below.

There were some suggestions that Will considered. One of them was to allow the robot to recognize the ping-pong balls on its own and pick them up. Initially Will did think of using OpenCV for accomplishing this, but then he found that people are more excited at driving a robot around and had more fun. Another suggestion that Will is considering for the future is using a vacuum pick up, since ping-pong balls are very light, and easily slip away from the robot’s fingers.