Adaptive RSSI-based localization scheme for wireless sensor networks

Range of applications for Wireless Sensor Networks (WSNs) is increasing rapidly. One class of such applications is Energy-Aware Wireless Positioning Systems for situation awareness. Localization deals with determining a target node’s position in WSN by analyzing signals exchanged between nodes. Received Signal Strength Indicator (RSSI) represents the ratio between received signal power and a reference power, and is typically used to estimate distances between nodes. RSSI distance estimations are affected by many factors. This paper aims to enhance the accuracy of RSSI-based localization techniques in ZigBee Networks through studying the communication channel status between two nodes. As the network nodes are exposed to high noise levels, position estimation accuracy deteriorates. A novel adaptive localization scheme is proposed; Two-State Markov model with moving average is employed to detect unpredictable RSSI readings that may reflect badly on the estimation. The proposed scheme achieves better estimation accuracy, for example, the estimation error was reduced from 11.7 m to just 3 m using the proposed scheme.     

Tabu search for attribute reduction in rough set theory

In this paper, we consider a memory-based heuristic of tabu search to solve the attribute reduction problem in rough set theory. The proposed method, called tabu search attribute reduction (TSAR), is a high-level TS with long-term memory. Therefore, TSAR invokes diversification and intensification search schemes besides the TS neighborhood search methodology. TSAR shows promising and competitive performance compared with some other CI tools in terms of solution qualities. Moreover, TSAR shows a superior performance in saving the computational costs.     

[2.2]Paracyclophane-Based TCN-201 Analogs as GluN2A-Selective NMDA Receptor Antagonists

Recent studies have shown the involvement of GluN2A subunit-containing NMDA receptors in various neurological and pathological disorders. In the X-ray crystal structure, TCN-201 ( 1 ) and analogous pyrazine derivatives 2 and 3 adopt a U-shape (hairpin) conformation within the binding site formed by the ligand binding domains of the GluN1 and GluN2A subunits. In order to mimic the resulting π/π-interactions of two aromatic rings in the binding site, a [2.2]paracyclophane system was designed to lock these aromatic rings in a parallel orientation. Acylation of [2.2]paracyclophane ( 5 ) with oxalyl chloride and chloroacetyl chloride and subsequent transformations led to the oxalamide 7 , triazole 10 and benzamides 12 . The GluN2A inhibitory activities of the paracyclophane derivatives were tested with two-electrode voltage clamp electrophysiology using Xenopus laevis oocytes expressing selectively functional NMDA receptors with GluN2A subunit. The o-iodobenzamide 12 b with the highest similarity to TCN-201 showed the highest GuN2A inhibitory activity of this series of compounds. At a concentration of 10 μM, 12 b reached 36 % of the inhibitory activity of TCN-201 ( 1 ). This result indicates that the [2.2]paracyclophane system is well accepted by the TCN-201 binding site.     

Optimal DG Allocation in Radial Distribution Systems with High Penetration of Non-linear Loads

This paper addresses the optimal distributed generation sizing and siting for voltage profile improvement, power losses, and total harmonic distortion (THD) reduction in a distribution network with high penetration of non-linear loads. The proposed planning methodology takes into consideration the load profile, the frequency spectrum of non-linear loads, and the technical constraints such as voltage limits at different buses (slack and load buses) of the system, feeder capacity, THD limits, and maximum penetration limit of DG units. The optimization process is based on the Genetic Algorithm (GA) method with three scenarios of objective function: system power losses, THD, and multi-objective function-based power losses and THD. This method is executed on the IEEE 31-bus system under sinusoidal and non-sinusoidal (harmonics) operating conditions including load variations within the 24-hr period. The simulation results using Matlab environment show the robustness of this method in optimal sizing and siting of DG, efficiency for improvement of voltage profile, reduction of power losses, and THD. A comparison with particle swarm optimization (PSO) method shows that the proposed method is better than PSO in reducing the power losses and THD in all suggested scenarios.     

Defect mode in periodic and quasiperiodic one-dimensional photonic structures

The properties of one-dimensional periodic and quasiperiodic photonic crystals with a defect layer have been investigated. Transfer matrix method (TMM) has been used throughout this study. For periodic photonic crystals, results demonstrate the independence of the defect mode frequency on the defect layer while the defect mode transmission coefficient varies with the position of the defect layer position. On the other hand, defect mode frequency is not that responsive to the index of refraction of the defect layer. The quality factor of the defect mode has been studied as a function of the defect layer position as well as its thickness. For quasiperiodic photonic crystals, the frequency of the defect mode is very sensitive to the defect layer position as well as its thickness. An enhancement of the quality factor of the defect mode has been observed. This study may be valuable in designing optical devices and it may also provide a more accurate method to measure the index of refraction.     

Design and implementation of a hands-free electrolarynx device controlled by neck strap muscle electromyographic activity

The electrolarynx (EL) voice prosthesis is widely used, but suffers from the inconvenience of requiring manual control. Therefore, a hands-free EL triggered by neck muscle electromyographic (EMG) activity was developed (EMG-EL). Signal processing circuitry in a belt-mounted control unit transforms EMG activity into control signals for initiation and termination of voicing. These control signals are then fed to an EL held against the neck by an inconspicuous brace. Performance of the EMG-EL was evaluated by comparison to normal voice, manual EL voice, and tracheo-esophageal (TE) voice in a series of reaction time experiments in seven normal subjects and one laryngectomy patient. The normal subjects produced voice initiation with the EMG-EL that was as fast as both normal voice and the manual EL. The laryngectomy subject produced voice initiation that was slower than with the manual EL, but faster than with TE voice. Voice termination with the EMG-EL was slower than normal voice for the normal subjects, but not significantly different than with the manual EL. The laryngectomy subject produced voice termination with the EMG-EL that was slower than with TE or manual EL. The EMG-EL threshold was set at 10% of the range of vocal-related EMG activity above baseline. Simulations of EMG-EL behavior showed that the 10% threshold was not significantly different from the optimum threshold produced through the process of error minimization. The EMG-EL voice reaction time appears to be adequate for use in a day-to-day conversation.     

Fatigue Life Evaluation of Concrete Bridge Deck Slabs Reinforced with Glass FRP Composite Bars

Since bridge deck slabs directly sustain repeated moving wheel loads, they are one of the most bridge elements susceptible to fatigue failure. Recently, glass fiber-reinforced polymer (FRP) composites have been widely used as internal reinforcement for concrete bridge deck slabs as they are less expensive compared to the other kinds of FRPs (carbon and aramid). However, there is still a lack of information on the performance of FRP–reinforced concrete elements subjected to cyclic fatigue loading. This research is designed to investigate the fatigue behavior and fatigue life of concrete bridge deck slabs reinforced with glass FRP bars. A total of five full-scale deck slabs were constructed and tested under concentrated cyclic loading until failure. Different reinforcement types (steel and glass FRP), ratios, and configurations were used. Different schemes of cyclic loading (accelerated variable amplitude fatigue loading) were applied. Results are presented in terms of deflections, strains in concrete and FRP bars, and crack widths at different levels of cyclic loading. The results showed the superior fatigue performance and longer fatigue life of concrete bridge deck slabs reinforced with glass FRP composite bars.     

Design of Unskewed Interior Permanent Magnet Traction Motor with Asymmetric Flux Barriers and Shifted Magnets for Electric Vehicles

Abstract

Interior permanent magnet synchronous motors (IPMSMs) are commonly used in electric and hybrid electric vehicles. Nissan Leaf electric vehicle (EV) uses skewed-rotor IPMSM as a traction motor. This motor is considered as a benchmark in this work. Although, skewing improves the torque quality of the motor by reducing the torque ripple, it reduces the average torque and increases the motor manufacturing complexity and cost. This article proposes improvements to the benchmark motor torque quality without skewing. The proposed motor uses the same stator winding and rotor magnet topologies of the benchmark motor with the same geometric constraints and magnet volume. Modifications are applied to the placement of the magnets in the rotor and the shape of the flux barriers to achieve the performance requirements. The design procedure of the proposed unskewed design is illustrated. Moreover, the electromagnetic performance of the proposed design is investigated. The design shows competitive performance in terms of the average torque, torque ripple, cogging torque, and efficiency compared to the benchmark motor. The mechanical integrity of the design is also verified. The proposed design is found to be a suitable alternative to the benchmark traction motor with a reduced rotor weight and without skewing.