Current Issue : January - March Volume : 2011 Issue Number : 1 Articles : 10 Articles
This paper presents the application of dynamic voltage restorer (DVR) on Power distribution systems for mitigation of voltage sags at critical loads. DVR is one of the compensating types of custom power devices. This paper presents a selective harmonic elimination using diode clamped multi level inverter. These topologies are well suited for high-power, high-voltage level and low harmonic. Computer simulations results are presented to verify the performance of the 8 bus DVR system...
A novel battery recharging system for an all-electric driveline comprising a flywheel with a permanent magnet double wound synchronous machine (motor/generator) is presented. The double winding enables two voltage levels and two different power levels. This topology supersedes other all-electric drivelines. The battery operates in a low-power regime supplying the average power whereas the flywheel delivers and absorbs power peaks, which are up to a higher order of magnitude. The topology presents new challenges for the power conversion system, which is the focus of this investigation. The main challenge is the control of the power flow to the battery when the vehicle is parked despite the decay of the flywheel machine voltage; which is dependent on its charge state, that is, rotational speed. The design and simulation of an unidirectional DC/DC buck/boost converter for a variable rotational speed flywheel is presented. Conventional power electronic converters are used in a new application, which can maintain a constant current or voltage on the battery side. Successful PI current control has been implemented and simulated, together with the complete closed loop system....
Video applications using mobile wireless devices are a challenging task due to the limited capacity of batteries. The higher complex functionality of video decoding needs high resource requirements. Thus, power efficient control has become more critical design with devices integrating complex video processing techniques. Previous works on power efficient control in video decoding systems\r\noften aim at the low complexity design and not explicitly consider the scalable impact of subfunctions in decoding process, and seldom consider the relationship with the features of compressed video date. This paper is dedicated to developing an energyscalable video decoding (ESVD) strategy for energy-limited mobile terminals. First, ESVE can dynamically adapt the variable energy resources due to the device aware technique. Second, ESVD combines the decoder control with decoded data, through classifying the data into different partition profiles according to its characteristics. Third, it introduces utility theoretical analysis during the resource allocation process, so as to maximize the resource utilization. Finally, it adapts the energy resource as different energy budget and generates the scalable video decoding output under energy-limited systems. Experimental results demonstrate the efficiency of the proposed approach....
Green Networking can be the way to help reduce carbon emissions by the Information and Communications Technology (ICT) Industry. This paper presents some of the major components of Green Networking and discusses how the carbon footprint of these components can be reduced....
This paper is about the intelligent decision-making system for the smart grid based electricity market which requires distributed decision making on the competitive environments composed of many players and components. It is very important to consider the renewable energy and emission problem which are expected to be monitored by wireless communication networks. It is very difficult to predict renewable energy outputs and emission prices over time horizon, so it could be helpful to catch up those data on real time basis using many different kinds of communication infrastructures. On this backgrounds this paper provides an algorithm to make an optimal decision considering above factors....
Cutting force and energy are often used as parameters for monitoring the stone cutting process. Empirical models are required to guide the selection of the cutting conditions. This paper shows a simple empirical model to predict the variation of the cutting energy. It puts into relationship the cutting force and the cutting energy with the idealized chip thickness. It has been tested on six different kinds of stone. The models can be used to guide the selection of cutting conditions. The chip generation and removal process has been quantified with the intention of assisting both the toolmaker and the stonemason in optimizing the tool composition and cutting process parameters, respectively....
Today, many wireless devices are mobile and battery powered. Based on the fact that battery capacity is still limited, energy saving is an important issue in wireless communication.Meanwhile, the number of wireless devices continues to increase and this creates interference problems between wireless devices. In this paper, we look at transmission power control and propose a mechanism that tries to achieve minimum energy consumption or emission under any circumstance. Lower transmission power levels may result in more retransmissions, but in total, energy consumption or emission still can be reduced in many scenarios. To evaluate the performance of our mechanism, we used real wireless channels in an indoor environment to carry out measurements. The measurement results indicate that a significant amount of energy consumption or emission reduction can be achieved for the transmitter in most scenarios compared to using a fixed transmission power level for all packets....
A hybrid car is a means of transportation using two power sources; it uses a rechargeable energy storage system found on board and a fuelled power source as the vehicle’s driving force. The hybrid car pollutes less and uses less fuel. Since the 1990s hybrid cars have become a viable alternative to standard petrol or diesel cars. Petrol (gasoline) prices are creeping up and the consensus is they are likely to continue rising. The world's oil deposits are limited and many pundits believe that the amount of extractable oil available is likely to decline over the next few years. This means ever rising fuel prices (supply and demand).So, the logical thing to do is to find good alternatives to gasoline as a fuel and to become more efficient in using gas. Hybrid cars offer very real fuel savings so they are increasingly popular with motorists.A vehicle having an electric hybrid power system is provided. The vehicle includes an electric motor drivably connected to one or more ground engaging vehicles. A battery pack stores electricity to power the electric motor. An engine is drivably connected to the wheels with an alternator connected to the engine for recharging an accessory battery. The alternator has at least a voltage output range of between approximately the standard output voltage of the accessory battery and the standard output voltage of the battery pack. In accordance with the present invention, a mechanism for electrically connecting the alternator to the battery pack is provided such that the alternator recharges both the battery pack and the accessory battery....
We present a photovoltaic energy harvester, realized in 0.35-�µm CMOS technology. The proposed system collects light energy from the environment, by means of 2-mm2 on-chip integrated microsolar cells, and accumulates it in an external capacitor. While the capacitor is charging, the load is disconnected. When the energy in the external capacitor is enough to operate the load for a predefined time slot, the load is connected to the capacitor by a power management circuit. The choice of the value of the capacitance determines the operating time slot for the load. The proposed solution is suitable for discrete-time-regime applications, such as sensor network nodes, or, in general, systems that require power supply periodically for short time slots. The power management circuit includes a charge pump, a comparator, a level shifter, and a linear voltage regulator. The whole system has been extensively simulated, integrated, and experimentally characterized....
The use of compressed air as a potential zero pollution power source for motorbikes is new challenge. The motorbike is proposed to be installed with an air turbine transforms the energy of the compressed air into shaft work in place of an internal combustion engine. The paper describes a mathematical modeling and performance evaluation of a small capacity compressed air driven vaned type novel air turbine. The effect of isobaric admission and adiabatic expansion of high pressure air for different rotor to casing diameter ratios at optimum vane and injection angles as 45o, 60o respectively have been considered and analyzed. It is concluded that the work output is found optimum for some typical values of rotor / casing diameter ratios. In this study, the maximum power obtained for linear expansion as 3.977 kW (5.50 HP) when casing diameter is 100 mm and rotor to casing diameter ratio are 0.75 to 0.70 at 90 psi (6 bar) and speed of rotation 2500 rpm which is sufficient to run motorbike....
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