电气与电子系统杂志

In recent years, cases of vehicles being accidentally driven into the sea or flooded sewers have been frequently reported. However, due to strong external water pressure in such situations, drivers sometimes fail to open a door for escape, causing irreversible results. Moreover, the inhalation of dangerous gases, as generated by the air conditioner and circulated in the vehicle, can cause permanent damage to the occupants of the vehicles. Considering the abovementioned scenario, this author believes that if a device can break the windshield and automatically make an emergency phone call when the vehicle is under water and there is a gas leakage, it would enable drivers and passengers to immediately escape, thus, effectively improving their safety. Therefore, this study focuses on this issue as its major research direction and aim; moreover, a review of domestic and overseas research regarding vehicle safety devices and accessory products shows that such windshield-breaking devices do not exist.

This paper presents a comparative study of metaheuristics algorithms in evaluation of economic load dispatch problem in power generating station with MATLAB codes. In this paper, the formulation of the ELD problems using mathematical illustrations and MATLAB codes were presented. This consists of the ELD cost model, Model calculations, cost function and parse solution. It also presents the application of some metaheuristics algorithms (solution algorithms) such as ACSA and PSO in solving ELD problem with MATLAB codes. The ELD problem was modeling using Egbin thermal power station, Nigeria as our case study.

Distributed generators (DGs) play a vital role in present power distribution networks. The integration of distributed generators in distribution systems require optimal placement and sizing of distributed generators to yield minimum power losses and improved voltage profile. Often single DG placement may not be sufficient for power distribution system and multiple DGs may be required to be integrated to power distribution network. Concerning this, optimal location of multiple DGs in power distribution systems is very important. This paper presents a Particle Swarm Optimization (PSO) based algorithm for optimal location of multiple DGs into the power distribution network for power loss minimization. The proposed algorithm has two major steps; first step is the finding of optimal location and active power injections of multiple DGs and later is the computation of optimal reactive power injection of DGs. A bio-inspired particle swarm optimization algorithm is used in the first step to locate multiple DGs optimally and to obtain optimal active power injections of DGs. In the second step, reactive power injections of DGs are selected based on the reactive power requirement of the area fed by the DG. The proposed method is successfully tested on IEEE 13 bus system and its performance has been benchmarked with the Improved Analytical method.

Study of human pathologies and acquisition of anatomical images without any surgical intervention inside human body is possible because of magnetic resonance imaging (MRI). This work exploits the notable properties of zero permeability (0 μ) split ring resonators (SRR) metamaterial (MM) magnetic polarizer which could distort, control and reject uniform RF (radio frequency) magnetic field for 1.5-T MRI systems. Unique polarizer was proposed to etch on PCB (printed circuit board) slabs for compact thickness of 5 mm only. In addition, polarizer was loaded with novel combination of parametric elements (capacitors, inductors) which could made the structure tunable to achieve resonance at different working frequencies. We achieved the value of relative permeability, μ_r=0.02+j0.1 for 1.5-T MRI systems at 63.85 MHz. Furthermore polarizer, when used with MRI scanner at optimized position, uniformly redistributed and enhanced the magnetic field while lowered specific absorption ratio (SAR), induced electric field, power dissipation, and locally improved SNR (signal to noise ratio) at the scanned region of phantom {real case was human body}. The polarizer minimized the damaging effects of RF energy absorption in human tissue and prevented them from heating.

This paper proposed a modification of the Artificial Fish Swarm Algorithm (AFSA) using adaptive behaviour base combination of normative and situational knowledge inherent in cultural algorithm. Four variations (wCAFSA_ Ns, wCAFSA_Sd, wCAFSA_NsSd and wCAFSA_NsNd) of the AFSA called weighted Cultural Artificial Fish Swarm Algorithm (wCAFSA) were then proposed with the hope of reducing the chance of falling into local minima by the standard AFSA. The performances of these were first evaluated using a collection of seven optimizations benchmark functions. Thereafter, all the variants were used to design an optimized PID controller for the dc motor of deep space antenna azimuth position control with the hope of minimizing the cost function and maximizing the steady state responses. Simulation results demonstrated the effectiveness of the algorithms in determining efficiently the optimized PID controller gains. Even though all the developed algorithms demonstrated their effectiveness, the wCAFSA_NsSd appears to be more efficient.

The inability to quickly isolate the faulty sections of the direct current (DC) network damages the converters and the transmission system. Further delay in fault interruption can be escalated to the generation system thus shutting down the whole power system. Currently, Voltage Source Converter-High Voltage Direct Current (VSC-HVDC) systems provide the best mode of bulky power transmission over long distance. Though VSC-HVDC have their own internal protection, they still suffer from short-circuit faults especially on the DC side hence requiring a novel fast DC breaker. The novel design of the DC breaker in this paper utilizes a systematically calculated mutual inductance to divert the energy generated during fault to resistive elementson both sides of the DC breaker thus, preventing the transient voltage and backward current generated at the time of clearing the fault. The major challenge for DC breaker is that current is not alternating inferring that it has no natural zero current occurring point. Thus, the current has to be artificially forced to cross a current zero point so that the fault can be easily interrupted.This study aims at reviewing the currently available DC breakers with a fault clearing time of 5msby modelinga novel fast DC breaker therefore, providing the best possible protection against short-circuit faults on VSC systems. The results indicate that the proposed DC breaker model has a fault clearing time of 1ms. This is a major contribution towards the development a fast DC breaker.