In this paper, a novel adaptive PID-like controller is introduced. Compared to the conventional methods, better responses are achieved by using the proposed method. The proposed controller is based on neural networks ...
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ISBN:
(纸本)9781424487554
In this paper, a novel adaptive PID-like controller is introduced. Compared to the conventional methods, better responses are achieved by using the proposed method. The proposed controller is based on neural networks technology and is applied to different kind of black box systems, linear or nonlinear systems and time variant and/or time invariant systems. Generally speaking, it is known that classical tuning methods for PID controllers provided unsatisfactory results for industrial plants where the time delay exceeds the dominant lag time;that is the reason for studying alternative strategies. In this context the most popular rule is Smith predictor. Generally, dead time is a variable parameter and leads to changing the model of system during process of control. Therefore we need to estimate this variable parameter using an online algorithm. We have done and proven this estimation via Smith rule for different systems with first order or second order models. In order to show the actual performances of mentioned methods, we have run them on the level control of tanks in water refinement process of Neka power plant which generally is a very nonlinear and delayed system. In order to control this system we apply our neural networks controller and Smith predictor rule simultaneously. Simulation results in this chapter show the perfect performance of our adaptive controllers and rules.
Low-cost and low-power sensor nodes forming Wireless Sensor Networks have become suitable for a wide range of applications during recent years. These networks demand the implementation of energy-aware techniques and l...
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ISBN:
(纸本)9780769528892
Low-cost and low-power sensor nodes forming Wireless Sensor Networks have become suitable for a wide range of applications during recent years. These networks demand the implementation of energy-aware techniques and low complexity protocols in all layers. Recently, a MIMO - based structure has been proposed to offer enhanced energy savings in WSNs, compared with simple SISO transmission. In this paper we consider the most common transmission structure for WSNs, using multiple hops. We examine and compare MIMO - based WSN with a multihop transmission in terms of energy efficiency. The results mainly depend on the channel conditions and the distance to the destination node. We reach analytical expressions to calculate threshold values of these parameters, which determine the areas where the MIMO - based structure outperforms multihop transmission.
Low-cost and low-power sensor nodes forming Wireless Sensor Networks (WSNs) have become suitable for a wide range of applications during recent years. These networks, due to their special functional characteristics, d...
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ISBN:
(纸本)9781424426430
Low-cost and low-power sensor nodes forming Wireless Sensor Networks (WSNs) have become suitable for a wide range of applications during recent years. These networks, due to their special functional characteristics, demand the implementation of energy-aware techniques in all layers. Recently a MIMO based structure has been proposed to offer enhanced energy savings in WSNs under certain circumstances. Based on that idea several alternatives have been examined, mainly focusing on 2x2 MEMO systems. In this paper, we summarize two MIMO schemes and compare their performance in terms of energy efficiency. Moreover, we investigate more complex NUM systems, emphasizing on 4x4 structures, and prove that depending on the scenario, such systems may offer remarkable energy gains.
Orthogonal frequency division multiplexing (OFDM) is a very popular modulation scheme because it requires a very simple receiver in transforming a frequency-selective channel into multiple flat-fading channels. Furthe...
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ISBN:
(纸本)9781424493326
Orthogonal frequency division multiplexing (OFDM) is a very popular modulation scheme because it requires a very simple receiver in transforming a frequency-selective channel into multiple flat-fading channels. Furthermore, multiple-input-multiple-output (MIMO) OFDM systems employing transmit diversity techniques, such as space-time (ST) and space-frequency (SF) coding, increase robustness and reliability over wireless fading channels. However, time-variation of the channel due to mobility disrupts orthogonality among subcarriers and yields intercarrier interference (ICI), limiting the performance of OFDM. In this paper we first recall a reduced-complexity technique to mitigate ICI in single-input-single-output (SISO) OFDM systems denoted per sub-block equalization (PSE) which operates on sub-blocks of the received OFDM symbol. Next we propose an extension of PSE to MIMO SF-OFDM systems. In particular, the Alamouti scheme is used in conjunction with PSE to combat ICI. Performance of the proposed scheme is evaluated for mobile digital video broadcasting DVB-T2 2 x 1 and 2 x 2 MIMO scenarios that suit with a possible extension to handheld devices in a next generation DVB-H. Numerical results show that the new receiver provides a gain from 21% to 33% with respect to the conventional OFDM receiver in terms of vehicular speed at which a target bit error rate can be maintained.
Recently, coordinated multiple-point transmission (CoMP) is one of important techniques needed to minimize intercell interference (ICI). In general, the transmission in CoMP - joint processing transmission (CoMP-JPT) ...
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Low-cost and low-power sensor nodes forming Wireless Sensor Networks (WSNs) have become suitable for a wide range of applications during recent years. These networks, due to their special functional characteristics, d...
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ISBN:
(纸本)9781424403523
Low-cost and low-power sensor nodes forming Wireless Sensor Networks (WSNs) have become suitable for a wide range of applications during recent years. These networks, due to their special functional characteristics, demand the implementation of energy-aware techniques in all layers. Recently a MIMO - based structure has been proposed to offer enhanced energy savings in WSNs under certain circumstances. In this paper, we present a detailed analysis of the dissipated power during a sensor node's operation, to prove that as microelectronics develop the MIMO - based architecture will outperform the equivalent SISO structure for almost any case, in terms of energy efficiency. Moreover, we introduce a simple Cooperative Node (CN) Selection algorithm to achieve additional energy gains in the MIMO approach along with enhanced network lifetime. We examine the scalability of the algorithm on different channel conditions and varying network density, and investigate the effect of the power dissipation analysis on its efficiency.
This paper proposes the joint beamforming space-time block coding (JBSTBC) scheme for multi-input multi-output (MIMO) communication systems. To enhance the order of spatial diversity in presence of deteriorate fading ...
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This paper proposes the joint beamforming space-time block coding (JBSTBC) scheme for multi-input multi-output (MIMO) communication systems. To enhance the order of spatial diversity in presence of deteriorate fading correlations as well as inter-substream interferences, the proposed JBSTBC method employs joint eigen-beamforming technique together with the block-ordered layered detector (BOLD) for MIMO-STBC. In order to confirm the superiority of the proposed JBSTBC method, computer simulations are conducted in highly correlated fading situations while providing detailed mathematical derivations for clarifying functionality of the proposed scheme.
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