Sensorless stator field orientation controlled induction motor drive with a fuzzy speed controller

AbstractA sensorless stator-field oriented control induction motor drive with a fuzzy logic speed controller is presented. First, a current-and-voltage parallel-model stator-flux estimator is established using measured phase currents and voltages of the induction motor. Then the estimated rotor shaft position is obtained from the magnitude and position of the estimated stator flux. The speed controller is developed by utilizing fuzzy logic control techniques. The control algorithms are realized by a DSP 6713 and, using a DSP F2812 to generate PWM signals to the power stage, drive the motor to experimentally validate the proposed approach

Low-complexity face-assisted video coding

[[abstract]]This paper presents a novel face-assisted video coding scheme to enhance the visual quality of the face regions in video telephony applications. A skin-color based face detection and tracking scheme is proposed to locate the face regions in real-time. After classifying the macroblocks into the face and non-face regions, we present a dynamic distortion weighting adjustment (DDWA) scheme to drop the static non-face macroblocks, and the saved bits are used to compensate the face region by adjusting the distortion weighting of the face macroblocks. The quality of face regions will thus be enhanced. Moreover, the computation originally required for the skipped macroblocks can also be saved. The experimental results show that the proposed method can significantly improve the PSNR and the subjective quality of face regions, while the degradation introduced on the non-face areas is relatively insensitive to human perception. The proposed algorithm is fully compatible with the H.263 standard, and the low complexity feature makes it well suited to implement for real-time applications[[fileno]]2030144030041[[department]]電機工程學

Gender Determination using Fingerprint Features

Several previous studies have investigated the gender difference of the fingerprint features. However, regarding to the statistical significance of such differences, inconsistent results have been obtained. To resolve this problem and to develop a method for gender determination, this work proposes and tests three fingertip features for gender determination. Fingerprints were obtained from 115 normal healthy adults comprised of 57 male and 58 female volunteers. All persons were born in Taiwan and were of Han nationality. The age range was18-35 years. The features of this study are ridge count, ridge density, and finger size, all three of which can easily be determined by counting and calculation. Experimental results show that the tested ridge density features alone are not very effective for gender determination. However, the proposed ridge count and finger size features of left little fingers are useful, achieving a classification accuracy of 75% (P-valu

Obstacle-Resistant Deployment Algorithms for Wireless Sensor Networks

[[abstract]]Node deployment is an important issue in wireless sensor networks (WSNs). Sensor nodes should be efficiently deployed in a predetermined region in a low-cost and high-coverage-quality manner. Random deployment is the simplest way to deploy sensor nodes but may cause unbalanced deployment and, therefore, increase hardware costs and create coverage holes. This paper presents the efficient obstacle-resistant robot deployment (ORRD) algorithm, which involves the design of a node placement policy, a serpentine movement policy, obstacle-handling rules, and boundary rules. By applying the proposed ORRD, the robot rapidly deploys a near-minimal number of sensor nodes to achieve full sensing coverage, even though there exist unpredicted obstacles with regular or irregular shapes. Performance results reveal that ORRD outperforms the existing robot deployment mechanism in terms of power conservation and obstacle resistance and, therefore, achieves better deployment performance.[[incitationindex]]SC

Dynamic region of interest transcoding for multipoint video conferencing

This paper presents a region of interest transcoding scheme for multipoint video conferencing to enhance the visual quality. In a multipoint videoconference, usually there are only one or two active conferees at one time which are the regions of interest to the other conferees involved. We propose a Dynamic Sub-Window Skipping (DSWS) scheme to firstly identify the active participants from the multiple incoming encoded video streams by calculating the motion activity of each sub-window, and secondly reduce the frame-rates of the motion inactive participants by skipping these less-important subwindows. The bits saved by the skipping operation are reallocated to the active sub-windows to enhance the regions of interest. We also propose a low-complexity scheme to compose and trace the unavailable motion vectors with a good accuracy in the dropped inactive sub-windows after performing the DSWS. Simulation results show that the proposed methods not only significantly improve the visual quality on the active subwindows without introducing serious visual quality degradation in the inactive ones, but also reduce the computational complexity and avoid whole-frame skipping. Moreover, the proposed algorithm is fully compatible with the H.263 video coding standard. 1

Power Allocation and Time-Domain Artificial Noise Design for Wiretap OFDM with Discrete Inputs

Optimal power allocation for orthogonal frequency division multiplexing (OFDM) wiretap channels with Gaussian channel inputs has already been studied in some previous works from an information theoretical viewpoint. However, these results are not sufficient for practical system design. One reason is that discrete channel inputs, such as quadrature amplitude modulation (QAM) signals, instead of Gaussian channel inputs, are deployed in current practical wireless systems to maintain moderate peak transmission power and receiver complexity. In this paper, we investigate the power allocation and artificial noise design for OFDM wiretap channels with discrete channel inputs. We first prove that the secrecy rate function for discrete channel inputs is nonconcave with respect to the transmission power. To resolve the corresponding nonconvex secrecy rate maximization problem, we develop a low-complexity power allocation algorithm, which yields a duality gap diminishing in the order of O(1/\sqrt{N}), where N is the number of subcarriers of OFDM. We then show that independent frequency-domain artificial noise cannot improve the secrecy rate of single-antenna wiretap channels. Towards this end, we propose a novel time-domain artificial noise design which exploits temporal degrees of freedom provided by the cyclic prefix of OFDM systems {to jam the eavesdropper and boost the secrecy rate even with a single antenna at the transmitter}. Numerical results are provided to illustrate the performance of the proposed design schemes.Comment: 12 pages, 7 figures, accepted by IEEE Transactions on Wireless Communications, Jan. 201