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Energy efficiency is the main concern of research community while designing routing protocols for wireless sensor networks (WSNs). This concern can be addressed by using energy-harvesting scheme in routing protocols. In this paper, we propose a secure routing protocol that is based on cross layer design and energy-harvesting mechanism. It uses a distributed cluster-based security mechanism. In the cross-layer design, parameters are exchanged between different layers to ensure efficient use of energy. Energy-harvesting system is used to extract and store energy, which is used to take decisions for the node state and thus for the routing issues. Simulation results show that our routing protocol can perform better in many scenarios and in hostile attack-prone environment.

A novel maximum power point tracking (MPPT) technique based on mutual coordination of two photovoltaic (PV) modules/arrays has been proposed for distributed PV (DPV) systems. The proposed technique works in two stages. Under non-mismatch conditions between PV modules/arrays, superior performance stage 1 is active, which rectifies the issues inherited by the perturb and observe (P&O) MPPT. In this stage, the technique revolves around the perturb and observe (P&O) algorithm containing an intelligent mechanism of leader and follower between two arrays. In shading conditions, stage 2 is on, and it works like conventional P&O. Graphical analysis of the proposed technique has been presented under different weather conditions. Simulations of different algorithms have been performed in Matlab/Simulink. Simulation results of the proposed technique compliment the graphical analysis and show a superior performance and a fast response as compared to others, thus increasing the efficiency of distributed PV systems.

A thin layer of Al2O3nanoparticles has been deposited on top of a water-free PEDOT layer to modify wettability for obtaining pinhole-free homogenous tin-based perovskite films, resulting in better device performance.

Turbocharger centrifugal compressors are equipped with a “ported shroud” to reduce flow instabilities at low mass flow rate. This passive stability control device using flow recirculation has been demonstrated to extend the surge margin of a compressor, without substantially sacrificing performance. However, the actual working mechanisms of the system remain not well understood. In this paper, the relationship between inlet flow recirculation and instability control is studied using stereoscopic particle image velocimetry (PIV) in conjunction with dynamic pressure transducers at the inlet of a turbocharger compressor with and without a ported shroud. Both stable and unstable operational points are analyzed with use of phase-locked PIV measurements in surge. Detailed description of unstable flow in a centrifugal compressor is presented with the reconstruction of the complex flow structure evolution at the compressor inlet during surge. Rather than one-dimensional, the surge flow is described by a three-dimensional axisymmetric structure of combined entering and exiting swirling flows, alternating in magnitude during the self-excited pressure cycle. The correlation between pressure and velocity measurements shows that the development of compressor unsteadiness is accompanied with swirling reversed flow at the impeller tip. The influence of the ported shroud on the inlet velocity flowfield is seen with the presence of localized flow recirculation. Stability improvement with a ported shroud is thus explained by removing swirling backflow at the impeller inducer tip and recirculating it to the impeller inlet to increase the near shroud inlet blade loading and incidence angle.

A power system stabilizer using the fuzzy logic is designed and implemented in this paper. Simulation studies are performed to evaluate the performance of the fuzzy logic power system stabilizer (FLPSS) and PID power system stabilizer (PIDPSS). Genetic algorithms have been used to optimize the parameters of the fuzzy and PID stabilizers. To validate the design, different types of disturbances are applied to the system and the results of both stabilizers are compared. The simulation studies show that the fuzzy stabilizer provides a relatively better performance comparable to that of the PIDPSS over a wide range of operating conditions. The FLPSS and PIDPSS have also been experimentally implemented using MATLAB/Real-Time Windows Target toolbox software on a laboratory set up to model a simple power system of 1 KVA machine connected to an infinite bus through a transmission line. Experimental tests and results revealed the effectiveness of FLPSS, especially in vulnerable operating points.

This paper presents a new practical framework for evaluating reliability levels associated with power system supply-demand balance. The framework has been developed as part of a recent major industry-supported research and development study. The novel framework is based on three metaphors (dimensions) representing the relationship between available generation capacities and required demand levels. The first metaphor defines whether or not the capacity exists, the second metaphor defines whether or not the capacity is needed, and the last metaphor defines whether or not the capacity can reach (delivered to) the demand. The eight possible combinations associated with the 0/1 (Yes/No) values of the three metaphors would, in turn, define a set of powerful system-wide performance quality measures relating to generation deficiency, redundancy, bottling, etc. Practical applications to a portion of the Saudi power grid are also presented for demonstration purposes. The work of the paper constitutes a new line of research in system reliability assessment where the derived system-wide performance quality indices are capable of addressing and revealing areas of deficiencies and bottlenecks as well as redundancies in the composite generation- demand structure of large-scale power grids. In addition, the sensitivities of the performance quality indices with respect to variations in the system operating parameters represent powerful information, which can be used to assess the level of degradation in the reliability measure or the performance quality index under consideration.