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This paper presents an accurate method of calculating the switching device losses in a half bridge DC-AC inverter. The analysis is based on an existing numerical method of calculating the inductor ripple current. The losses are calculated by replicating the exact current waveform flowing through the switching devices. This method allows for a more accurate loss calculation than the well-known existing...
This paper presents the design, implementation and experimental platform of a low-cost intelligent wheelchair for the motor-disabled. The first prototype developed is an electric power wheelchair which cost is one third of the commercially available ones and is capable of both manual and autonomous operation. Manual operation relies on a joystick and is intended for people that, in spite of their...
Multilevel topologies have emerged as a viable technique for medium and high voltage inverters but in the low voltage range they have failed to attract much interest due to their increased cost associated with the additional components and complicated control. This paper proposes a new and simplified control strategy for a nine-cascaded neutral-point -clamped (NPC)/H-bridge PWM inverter. The new control...
The global electrical energy consumption is steadily rising and therefore there is need to increase the power generation capacity. The required capacity increase can be based on renewable energy. Photovoltaic energy remains a largely unexploited renewable energy source due to low conversion efficiency of the photovoltaic modules. To maximize the power derived from the PV systems it is important to...
In this paper a new application of the wavelet packet cosine transform (WPCT), used in the adaptive wavelet parameterization scheme, is presented. This is an extension of the best basis algorithm. Obtained optimized wavelet decomposition schemes are used for speech feature extraction and are tested using Polish language hidden Markov model (HMM) phone-classifier.
This paper presents a comparative theoretical study of the performance of a set of controllers for improving the speed of actuators based on shape memory alloys (SMAs), especially on Nitinol (NiTi). To prevent overheating and thermal fatigue, these controllers take into account the maximum heating current at which a NiTi element can safely be heated. The thermal behavior of NiTi is first modeled for...
In this paper a three-phase linear permanent magnet generator is designed for direct waves energy conversion. Its performance is then simulated using analytical and finite element method. Cogging force in this generator causes the oscillatory output power, shortens life time and increases the maintenance cost of the generator. Effects of design parameters including permanent magnet (PM) length, skewed...
Three evolutionary computing algorithms are applied to a constrained parameter, combinatorial optimization problem; the Sudoku puzzle. These methodologies include, quantum simulated annealing, cultural genetic algorithm and a hybrid between simulated annealing and genetic algorithm. The results obtained from these techniques indicate that the most effective of these optimization techniques is quantum...
Recently, robotic surgical assistance systems are in clinical use in the field of minimally invasive surgery. We have developed a multiDOF robotic forceps manipulator using a novel omnidirectional bending technique, so far. The developed robotic forceps can bend without using wires. Without wires, it has high rigidity, and it can bend at 90 degrees in any arbitrary direction. The purpose of this paper...
This paper presents the numerical analysis of the influence of the presence of cylindrical voids in electric cables. Size, length and depth of voids are determinants of the discharge inception voltage. This analysis has been done with 2D and 3D finite element models and results have been compared with analytical formulas. The influence of depth in cylindrical voids has been analysed and discussed.
Next generation wireless networks will interwork hence combine resources of the available heterogeneous networks for connection support. Mobility across these networks will be inevitable. Thus, to support seamless connection migration between the networks, seamless handover is a necessary requirement. One of the requirements for ensuring seamless handover is the reduction of the delay that occurs...
In this paper, a tunable fuzzy logic based servo controller for monitoring and control of the micro-electro discharge machining (micro-EDM) process has been developed, which uses the behavior of discharge pulses. The fuzzy logic applies a heuristic approach in dealing with the non-linear and time varying nature of the micro-EDM process. The control parameters affecting the performance of micro-EDM...
Problems of estimation in statistical inference are mainly generalized by the samples. Assigned numerical values to a population parameter will expect a close estimation based on the available sample. In this paper, a use of sequential response surface methodology (sequential-RSM) is proposed for the power system state estimator solution. Offline Data (measurements and the state variables) are collected...
In this paper, we propose a novel packet scheduler for satellite high speed downlink packet access (S-HSDPA) air interface. We have considered a geostationary bent-pipe satellite for this work. Satellite systems are meant to complement the terrestrial access network to provide seamless global roaming and are expected to connect to the same core network. A cross-layer approach was used in designing...
The wireless mesh network (WMN) backbone is usually comprised of stationary nodes but the transient nature of wireless links results in changing network topologies. Topology Control (TC) aims to preserve network connectivity in ad hoc and mesh networks and an abundance of theoretical results on the effectiveness of TC exist. Practical evaluations of TC schemes that provide gradual transceiver power...
Nowadays robots can recognize their environment in a limited way. Future robots designed for operations in a natural environment and for communicating with humans in a natural way require the fusion of data acquired from spoken words and sensory data from the surrounding area. By means of intelligent sensors for speech recognition, proximity measurement, colour measurement and image processing an...
This paper deals with a design problem of non-minimum phase systems with input constraints and unknown disturbance using the adaptive robust anti-windup generalized predictive control (RAGPC) scheme. In essence non-minimum phase systems are characterized by presence of dead time and invariably has unstable inverse. This effect is not desirable in control processes especially when problems of static...
Performance of wireless OFDM systems significantly depends on channel estimation accuracy. However, it is difficult to take into account all possible scenarios as the variance of error at the output of the minimum mean square error (MMSE) estimator depends on the second-order channel statistics. In this paper, we derive the lower and the upper MSE bounds, characterising the best and the worst-case...
In this work, we consider the use of multiple antenna signaling technologies, specifically space-time block coding (STBC) and spatial multiplexing (SM) schemes, in multiple-input multiple-output (MIMO) communication systems employing dual polarized antennas at both ends. The use of dual-polarized antennas theoretically double the number of virtual antennas used in the system. On the other hand, the...
Video games are ubiquitous in modern day life. Unfortunately, several children are overweight or even obese because they spend a lot of time watching television or playing non-physical video games, instead of perfoming physical activities. Furthermore, this lack of exercise affects their development. The fact that children are becoming overweight or obese is a health concern for many countries that...
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