Adaptive Piezoelectric energy harvesting circuit

This paper describes an approach to harvesting electrical energy from a mechanically excited piezoelectric element. A vibrating piezoelectric device differs from a typical electrical power source in that it has a capacitive rather than inductive source impedance, and may be driven by mechanical vibrations of varying amplitude. An analytical expression for the optimal power flow from a rectified piezoelectric device is derived, and an “energy harvesting “ circuit is proposed which can achieve this optimal power flow. The harvesting circuit consists of an ac-dc rectifier with an output capacitor, an electrochemical battery, and a switch-mode dc-dc converter that controls the energy flow into the battery. An adaptive control technique for the dc-dc converter is used to continuously implement the optimal power transfer theory and maximize the power stored by the battery. Experimental result reveal that the use of the adaptive dc-dc converter increases power transfer by over 400% as compared to when the dc-dc converter is not used.

Coordinated secondary voltage control to eliminate voltage violation in power system contingencies

In order to achieve more efficient voltage regulation in a power system, coordinated secondary voltage control has been proposed, bringing in the extra benefit of enhancement of power system voltage stability margin. The study is presented by the e.g. with two SVCs and two STATCOMs in order to eliminate voltage violation in systems contingencies. In the paper, it is proposed that the secondary voltage control is implemented by a learning fuzzy logic controller. A key parameter of the controller is trained by P-type learning algorithm via offline simulation with the assistance of injection of artificial loads in controller’s adjacent locations. A multiagent collaboration protocol, which is graphically represented as a finite state machine, is proposed in the paper for the coordination among multiple SVCs and STATCOMs. As an agent, each SVC or STATCOM can provide multilocation coverage to eliminate voltage violation at its adjacent nodes in the power system. Agents can provide collaborative support to each other which is coordinated according to the proposed collaboration protocol.

Molecular Electronics:A new technology competitive to semiconductor technology

Semiconductor integration beyond Ultra Large Scale Integration (ULSI), through conventional electronic technology facing some problems with fundamental physical limitations. Beyond ULSI, a new technology may become competitive to semiconductor technology. This new technology is known is as Molecular Electronics.

Molecular based electronics can overcome the fundamental physical and economic issues limiting Si technology. Here, molecules will be used in place of semiconductor, creating electronic circuit small that their size will be measured in atoms. By using molecular scale technology, we can realize molecular AND gates, OR gates, XOR gates etc.

The dramatic reduction in size, and the sheer enormity of numbers in manufacture, are the principle benefits promised by the field of molecular electronics

Tele-Immersion (TI) :Free full Engineering seminar reort

It is 2010 and you have a very important meeting with your business associates in Chennai. However you have visitors from Japan coming for a mega business deal the same day. Is there any technology by which you can deal with both of them? The answer is yes and the name of that technology is Tele-Immersion. Tele-Immersion is a technology by which you’ll interact instantly with your friend on the other side of the globe through a simulated holographic environment. This technology, which will come along with Internet2, will change the way we work, study and get medical help. It will change the way we live. Tele-Immersion (TI) is defined as the integration of audio and video conferencing, via image-based modeling, with collaborative virtual reality (CVR) in the context of data-mining & significant computation. The 3D effect behind the tele-immersion makes it feel like the real thing. The ultimate goal of TI is not merely to reproduce a real face-to-face meeting in every detail, but to provide the “next generation” interface for collaborators, world-wide, to work together in a virtual environment that is seamlessly enhanced by computation and large databases. When participants are tele-immersed, they are able to see and interact with each other and objects in a shared virtual environment.

Tele-immersion can be of immense use in medical industry and it also finds its application in the field of education

Cylinder Deactivation: A fast emerging technology to save fuel

With alternatives to the petrol engine being announced ever so often you could be forgiven for thinking that the old favorite the petrol engine is on its last legs but nothing could be further from the truth and possibilities for developing the petrol engines are endless. One of the most crucial jobs on the agenda is to find ways of reducing fuel consumption, cutting emissions of the green house gas CO2 and also the toxic emissions which threaten air quality. One such fast emerging technology is cylinder deactivation where a number of cylinders are shut down when less is needed to save fuel.
The simple fact is that when you only need small amounts of power such as crawling around town what you really need is a smaller engine. To put it another way an engine performs most efficiently when its working harder so ask it to do the work of an engine half its size and efficiency suffers. Pumping or throttling losses are mostly to blame. Cylinder deactivation is one of the technologies that improve fuel economy, the objective of which is to reduce engine pumping losses under certain vehicle operating conditions.

When a petrol engine is working with the throttle wide open pumping losses are minimal. But at part throttle the engine wastes energy trying to breathe through a restricted airway and the bigger engine, the bigger the problem. Deactivating half the cylinders at part load is much like temporarily fitting a smaller engine.
During World War II, enterprising car owners disconnected a spark plug wire or two in hopes of stretching their precious gasoline ration. Unfortunately, it didn’t improve gas mileage. Nevertheless, Cadillac resurrected the concept out of desperation during the second energy crisis. The “modulated displacement 6.0L V-8- 6-4” introduced in 1981 disabled two, then four cylinders during part-throttle operation to improve the gas mileage of every model in Cadillac’s lineup. A digital dash display reported not only range, average mpg, and instantaneous mpg, but also how many cylinders were operating. Customers enjoyed the mileage boost but not the
side effects. Many of them ordered dealers to cure their Cadillacs of the shakes and stumbles even if that meant disconnecting the modulated-displacement system


Like wide ties, short skirts and $2-per-gallon gas, snoozing cylinders are back. General Motors, the first to show renewed interest in the idea, calls it Displacement on Demand (DoD). DaimlerChrysler, the first manufacturer to hit the U.S. market with a modern cylinder shut-down system calls its approach Multi- Displacement System (MDS). And Honda, who beat everyone to the punch by equipping Japanese-market Inspire models with cylinder deactivation last year, calls the approach Variable Cylinder Management (VCM)
The motivation is the same as before — improved gas mileage. Disabling cylinders finally makes sense because of the strides achieved in electronic power train controls. According to GM, computing power has been increased 50-fold in the past two decades and the memory available for control algorithms is 100 times greater. This time around, manufacturers expect to disable unnecessary cylinders so seamlessly that the driver never knows what’s happening under the hood.

MANUFACTURING THROUGH ELECTRO CHEMICAL MACHINING

ABSTRACT:
The machining of complex shaped designs was difficult earlier, but with the advent of the new machining processes incorporating in it chemical, electrical & mechanical processes manufacturing has redefined itself. This paper intends to deal with one of the revolutionary process called Electro Chemical Machining (ECM).

INTRODUCTION:
Electro chemical machining (ECM) is the controlled removal of metal by anodic dissolution in an electrolytic medium in which the work piece is the anode & the tool is the cathode.
Working: Two electrodes are placed at a distance of about 0.5mm & immersed in an electrolyte, which is a solution of sodium chloride. When an electrical potential of about 20V is applied between the electrodes, the ions existing in the electrodes migrate toward the electrodes.
Positively charged ions are attracted towards the cathode & negatively charged towards the anode. This initiates the flow of current in the electrolyte. The electrolysis process that takes place at the cathode liberates hydroxyl ions & free hydrogen. The hydroxyl ion combines with the metal ions of anode to form insoluble metal hydroxides &the material is thus removed from the anode. This process continues and the tool reproduces its shape in the work piece (anode). The high current densities promote rapid generation of metal hydroxides and gas bubble in the small spacing between the electrodes. These become a barrier to the electrolyzing current after a few seconds. To maintain a continuous high density current, these products have to be removed continuously. This is achieved by circulating the electrolyte at high velocity through the gap between the electrodes. It is also to be noted that the machining gap size increases. Therefore to maintain a constant gap the cathode should be advanced towards the anode at the same rate at which the material is removed.

CHEMICAL ROCKET ENGINES

Chemical rocket engines, like those on the space shuttle, work by burning two gases to create heat, which causes the gases to expand and exit the engine through a nozzle. In so doing they create the thrust that lifts the shuttle into orbit. Smaller chemical engines are used to change orbits or to keep satellites in a particular orbit. For getting to very distant parts of the solar system chemical engines have the drawback in that it takes an enormous amount of fuel to deliver the payload. Consider the Saturn V rocket that put men on the moon: 5,000,000 pounds of its total take off weight of 6,000,000 pounds was fuel. The problem is that all the energy for chemical engines comes from the energy stored in the propellants.
Electric rocket engines use batteries, solar power, or some other energy source to accelerate and expel charged particles. These rocket engines have extremely high specific impulses, so they are very efficient, but they produce low thrusts. The thrusts that they produce are sufficient only to accelerate small objects, changing the object’s speed by a small amount in the vacuum of space. However, given enough time, these low thrusts can gradually accelerate objects to high speeds. This makes electric propulsion suitable only for travel in space. Because electric rockets are so efficient and produce small thrusts, however, they use very little fuel. Some electric rockets can provide thrust for years, making them ideal for deep-space missions. Satellites or other spacecraft that use electric rockets for propulsion must be first boosted into space by more powerful chemical rockets or launched from a spacecraft.