Effect of standby mode operation of some household appliances on disturbance voltage and current in frequency range of 9–150 kHz produced by other equipment in low voltage network
Most household appliances commercially available today on the market are equipped with the inverter technology favoring to its smaller size, advanced performance, and energy efficient. Notwithstanding its benefits, unfortunately, this technology may introduce current disturbance according to its relevant frequency switching and eventually degrades power quality. The switching frequency of inverter for household appliances is generally in the range of 9-150 kHz causing the disturbance and may influence the working performance of other appliances. The voltage and current disturbances in the frequency range of 9-150 kHz are not completely covered and currently subject to standardization work. Some household appliances can be operated in standby mode in order to display the time and setting information or to allow them to operate quickly even though it also gives a drawback regarding to its energy consumed. This study investigates the characteristics of standby mode operation of some appliances and its effect to the voltage and current disturbance in the frequency range of 9-150 kHz. The result shows that the standby mode operation of particular household appliances can filter and significantly reduce the voltage and current disturbance in the low voltage (LV) installation network for specific frequency in the range of 9-150 kHz.
Equivalent circuit identification of standby mode operation for some household appliances in frequency range 9–150 kHz for the investigation of conducted disturbance in low voltage installations
Many household appliances can be operated in standby mode favoring to its benefit displaying the setting information and allowing them to switch on quickly. On Frequency range 9-150 kHz, standby mode operation of some household appliances particularly equipped by EMC filter have a very low impedance which can deliver any path for intentional and unintentional signals in that frequency range. This condition can influence the voltage and current disturbance on the network and need to be further observed. The study focused on identifying the equivalent circuit parameter of standby mode operation for particular household appliances. The equivalent circuit is useful to simulate and predict the behavior of voltage and current disturbance occurred in the low voltage distribution network when standby mode appliances are connected. The appliances under test chosen are inverter based microwave, conventional microwave, and induction stove. Based on the measurement, it can be noticed that for standby mode operation, the impedance of particular appliance has series and parallel resonance properties on specific frequency causing very low impedance at certain frequency in the range of 9-150 kHz.
Diversity of Electrospinning Approach for Vascular Implants: Multilayered Tubular Scaffolds
Abstract The biomimetics of biological structures found in nature remains one of the most promising approaches to engineer functional tissues from natural or synthetic biocompatible materials for the replacement of damaged or injured parts of the human body. Recently, medical therapeutic regimes have advanced into a new era, overcoming the known mechanical and biological variances that occur when using autologous or synthetic grafts. Basically, the core concept of tissue biofabrication, commonly referred to as tissue engineering, is to find out the favorable cellular microenvironments to grow a living tissue prior to clinical uses. In fact, the ability of stem cells to regenerate is controlled via signaling pathways (growth factors) and supporting materials (scaffolds) that guide the cellular activities. After the first successful experiments to fabricate polymer fibers from their solutions, Cooley proposed the use of an electric field a century ago (Cooley (US 692:631, 1902 ). The electrospinning technique has been continually developed as a fruitful polymer processing technique to draw ultrafine nonwoven fibers. Electrospun polymer fibers have been used for a wide range of technical and biotechnical applications such as filtration, organic solar cells, tissue engineering, and drug releasing implants. In this regard, this review begins with an overview about the various spinning approaches for the fabrication of polymer fibers as well as the basic principles of electrospinning process. In addition, this review will highlight vascular bypass surgery and, in particular, the needs for vascular tissue engineering. Finally, the review includes some of the latest attempts to improve the mechanical and biological properties of electrospun polymeric fibers and summarizes the challenges and prospects for the future. Lay Summary However, vascular defects are treated successfully via bypass surgical bypass grafting using autologous or synthetic vessels. The small-diameter vessels (less than 6) are often associated with high failure rate. This review reports some of the recent features that should be highlighted to fabricate an ideal graft for small-diameter vascular grafts. The review introduces multilayered conduits as an alternative approach to overcome the known mechanical and biological mismatches of single layered vascular grafts of electrospun polymers.