Engineering and Technology Journal

Directional sensors in wireless visual sensor networks attract growing attention as a promising tool for monitoring the real world; directional sensors consume energy for two main tasks: sensing and communication. Since a VSN contains a number of configurable visual sensors with changeable spherical sectors of restricted angle known as a field of view that is intended to monitor a number of targets located in a random manner over a given area. Therefore maximizing the network lifetime through minimizing power consumption while covering the targets remains a challenge. In this paper, the problem of obtaining a disjoint set cover includes a minimum number of camera sensors is solved. The problem is known to be NP-complete. The sustainable design is improving an existing Iterative Target Oriented Algorithm (ITOA) to cover moving targets move randomly over a given area of deployment starting from entry points reaching to exit ones in a realistic simulation. To evaluate the performance of the modified algorithm, a comparison is provided with three existing algorithms (Iterative centralized Greedy Algorithm (ICGA), Iterative Centralized Forced-directed Algorithm ICFA, and Iterative Target Oriented Algorithm ITOA). Simulation results revealed that the sustainable scheme can find a disjoint set with a minimum number of sensors covers the maximum number of moving targets in an energy-efficient way and extended network lifetime.

Recently the subject of energy-efficient is very important in cognitive radio (CR), especially during spectrum sensing, since the large energy consumption (EC) cost, produces a restriction in their implementation especially in devices with limited power, i.e battery. In these design, energy detector consumes a significant part of energy during spectrum sensing to detect the activity of the primary user (PU). In this paper, we investigated a method for improving EC in two scenarios: non-cooperative and cooperative. The idea behind the improvement is based on sensing the spectrum with low-density samples. The optimization concept for reducing EC through controlling the number of frequency samples to be sensed is illustrated as well as the probability of detection in both scenarios. To evaluate the proposed method a comparison is made between the proposed method and censoring method. The performance of energy detection system is evaluated in AWGN and Rayleigh fading channels. The simulation results show that in non-cooperative scenario at Eb/No equal 10 dB, and for sensing ratio equal 50%, EC decreases by 50% and 46% with sma loss in of detection probability of 5% in AWGN channel and 12% in Rayleigh channel. In cooperative scenario, the results show that as the number of cognitive users (CU) increased the average EC per user decreased with an improvement in probability of detection. In case of sensing ratio 50%, the EC is decreased by 43.6% as compared with censoring method.

To reduce the impact of the high current on the power grid from the start process of the large induction motor and eliminate the negative influences of traditional reduced voltage start on the electronic and mechanical equipments and enhance the ability of the energy saving of the system. We studied and improved the intelligent soft start of such motors, this paper presents the design of intelligent soft starting controller in viewpoint of energy saving for power electronic systems. The proposed controller was compared through experimental studies under identical conditions with the thyristor soft starting controller (conventional controller). The performance comparison is made on the aspects of power quality and energy saving advantages. It is found that
the proposed controller has superior operating and performance characteristics as compared to the conventional one.