Nonlinear Systems in Electrical Engineering
http://jnsee.sut.ac.ir
Journal of Nonlinear Systems in Electrical Engineering - Journal articles for year 2019, Volume 5, Number 1Yektaweb Collection - https://yektaweb.comen2019/2/12A New Blind Downlink Channel Estimation Method for Massive MIMO
http://jnsee.sut.ac.ir/jnsee/browse.php?a_id=171&sid=1&slc_lang=en
<p>Downlink channel estimation of Massive MIMO is an important challenge is 5G wireless communication. A classic method for this purpose is training-based method which leads to decreasing in transmitted information rate. To cope with this problem, recently, a blind channel estimation method has been presented in which by assuming that the value of large scale fading coefficient is known, the channel gain is estimated in multiuser Massive MIMO system. In this paper, we propose a new method that simultaneously estimates both channel gain and large scale fading coefficient by applying two different power control gain in the coherence interval. The proposed method is applicable for ZF and MR precoding. The proposed method has higher transmitted information rate (does not need to transmit the large scale fading coefficient) and lower MSE in high SNR values with respect to reference method.</p>
Mahmoud AtashbarTwo-stage estimation method presentation to improve electrical distribution networks state estimation
http://jnsee.sut.ac.ir/jnsee/browse.php?a_id=155&sid=1&slc_lang=en
<p>The development of renewable energy sources, distributed generation, energy storage and nonlinear controllable loads in modern distribution networks has led to the consideration of the state estimation in intelligent and active distribution networks. The performance of the Energy Management Central's distribution network depends on the results of the state estimation. In this paper, two-stage estimation with the network reduction process is proposed. The number of distribution network meter is low, so obtaining accurate initial information from network conditions improves performance state estimation. The initial state estimation with the network reduction process to obtain accurate initial data is performed. The initial data are used as a measure to improve the performance of secondary estimation. This method solves the problem of scarcity of accurate measurements and improves the accuracy of the state estimation in distribution network. The results of the proposed methodology are demonstrated on the 69 nodes of IEEE standard distribution network.</p>
Rasool KazemzadehA novel bridgeless ac-dc buck-boost converter fed brushless dc motors drive
http://jnsee.sut.ac.ir/jnsee/browse.php?a_id=160&sid=1&slc_lang=en
<p>In this paper, a novel structure based on Bridgeless AC/DC Converters for BLDC Motor is proposed. For now, to drive this kind of dc motors, step down and step up converters and converters with capability of increase and decrease in output voltage with bridgeless diode structures are presented. In this paper by using a novel structure, this possibility is provided to have a converter that can work in desired and separate states such as buck, boost or buck boost operations. In this paper focus will be upon buck-boost operation to access appropriate usage of both decrease and increase at output voltage advantages. Also this converter would not need to a diode bridge at primary of circuit. At output of this converter only a dc-link capacitor exists, that it will decrease the need of electrolytic capacitors that result to decreased circuit volume and cost. Removing of input diode bridge and input dc-link capacitor has caused to a better quality of input current waveforms. As well as, power factor for input power supply of this converter will work near to unit amounts.</p>
navid Taghizadegan kalantariAn Electrolytic Capacitor-less High Power Factor LED Driver with Pulsating Output Current
http://jnsee.sut.ac.ir/jnsee/browse.php?a_id=183&sid=1&slc_lang=en
<p style="margin-left:17.85pt;">Conventional Off-Line (50-60Hz) light emitting diode (LED) drivers usually need an electrolytic capacitor to reduce power imbalance between ac input and dc output, and to decrease the low-frequency component of the output ripple. However, electrolytic capacitor is the key component which limits the lifespan of LED driver. If a driver uses a pulsating output current, the electrolytic capacitor can be omitted. This paper proposes a high power factor LED driver with high frequency pulsating driving current, in which electrolytic capacitor has omitted from the topology. The driver has two outputs that allow the number of driving LEDs to increase, an LED string will be connected to each output and a single switch is used in series with each LED string, thus the number of switches is equal to the number of outputs. Output and Storage capacitor voltages are sensed and used to implement the control method to regulate the output current. Low cost and high efficiency can be obtained due to the power structure and the proposed control method. Simulations, calculations and experimental results are provided for the proposed circuit.</p>
Ali GhaemiThree-Dimensional Human Pose Estimation from a Single Image Using Non-linear Convolutional Neural Network Based on Shape Information
http://jnsee.sut.ac.ir/jnsee/browse.php?a_id=179&sid=1&slc_lang=en
<p style="margin: 16px 0px 4px; text-align: justify; unicode-bidi: embed; direction: ltr;"><span style="margin: 0px; color: rgb(13, 13, 13);"><font face="Times New Roman" size="2">3D human pose estimation is one of the most significant tasks in computer vision with wide range of applications. The works for estimating human pose initialized from 2D skeletal estimation from multiple data and has proceeded toward 3D skeletal estimation from minimum input information. In this paper, 3D human pose estimation from a single RGB image is investigated. The proposed work is considered as the ones which firstly estimate 2D pose and then lift the estimated 2D configuration to 3D space. Since most of the errors in this attitude are originated by inaccurate 2D pose inference, we have proposed a method for predicting more accurate 2D poses to obtain 3D poses with less errors. The proposed approach for estimating 2D pose has leveraged deep learning along with the information of the edge map. In other words, we have made use of edge features, which are hand-designed features, in order to guide the deep neural network in training and in learning the features in accordance with the defined objective. Experimental results have demonstrated less errors in 2D and consequently 3D pose estimation in Human3.6M and HumanEva-I benchmarks.</font></span></p>
hossein ebrahimnezhadStudy of the Nonlinear Effects of Squeeze Film Damping RF MEMS Ring Resonators
http://jnsee.sut.ac.ir/jnsee/browse.php?a_id=162&sid=1&slc_lang=en
<p><strong>Abstract:</strong>This paper presents an analytical study of the nonlinear effect of squeeze film damping on the previously designed ring shape anchored contour mode RF MEMS disk resonators. Varations of damping coefficient and stiffness constant of the resonator due to squeeze film phenomenon are evaluated and their efects on quality factor of the resonator is calculated. Analytical calculations mention that due to ultra high spring constant of the resonator, resulting frequency pulling and damping related to this effect could be neglected. Based on these derivations, there is no requirement for high price<br>
vacuum packaging for these resonators for increasing their quality factor. Extracting of the behavioral equations for the resonator in the presence of squeeze film effect is crucial in design of resonators in packaging, fabrication process and total cost points of view.</p>
Masoud Baghelani