The control of pulsed current gas metal arc (GMA) welding is highly critical owing to the simultaneous influence of the pulse parameters on thermal and metal transfer behaviours of the process. An analytical model has been developed to provide a theoretical understanding of the influence of pulse parameters on the behaviour of metal transfer and thermal characteristics in pulsed current GMA welding using Al-Mg filler wire. The variations in thermal and metal transfer behaviours with changes in pulse parameters have been satisfactorily analysed considering a summarised influence of pulse parameters defined by a dimensionless factor w5(I b /I p )ft b , proposed previously. A large number of process parameters have been considered, as a result of using four different GMA welding power sources. The hypothesis has been verified using some previously reported experimental results. The theoretical model may be useful in the control of pulse parameters to achieve desired behaviours of thermal and metal transfer under different conditions of weld fabrication, thereby facilitating more universal application of GMA welding. List of symbolsa acceleration of droplet due to plasma aerodynamic drag force, m s 22 A s total surface area of molten metal transferred per pulse, m 2 A w cross-sectional area of filler wire, m 2 C p specific heat of argon plasma510 4 J kg 21 K 21 C p(l) specific heat of liquid filler metal5 1130 J kg 21 K 21 C p(s) specific heat of solid filler metal5 1049 J kg 21 K 21 D diameter of droplets, m E w electrode extension520610 23 m f pulse frequency H A heat input due to arc heating, J s 21 H cv convective heat loss per unit mass of filler metal during flight from tip of filler wire to weld pool, J kg 21 H de heat content per unit mass of droplet at time of deposition, J kg 21 H dp heat content of total weld metal deposited per pulse, kJ H i heat content per unit mass of molten metal during its detachment from electrode, J kg 21 H O heat generated at tip of electrode per unit time, J s 21 H r radiative heat loss per unit mass of filler metal during flight from tip of filler wire to weld pool, J kg 21 H R heat input due to resistive heating, J s 21 H tl total heat loss during flight of molten metal transferred per pulse, kJ H w heat absorbed by filler wire per unit time, J s 21 I b base current, A I eff effective current, A I m mean current, A I p peak current, A j eff effective current density at tip of electrode, A m 22 j g current density of plasma in arc column, A m 22 j m mean current density at tip of electrode, A m 22 l arc length50 . 01 m L latent heat of filler wire53 . 97610 5 J kg 21 M t mass of filler wire transferred per pulse, kg N d number of molten filler metal droplets transferred per pulse N u Nusselt number P r Prandtl number r effective radius, m R resistance of electrode extension, V R e Reynolds number R O resistivity of filler wire50 . 25610 26 V m Science and Technology of Welding and Joining 2006 VOL 11 NO 2232 R w radius of filler wire50 . 8610 23 m t total pulse time t b base cur...

The authors would like to thank "Universidad Panamericana" for their support through the project "Estudio de topologías de convertidores de cd-cd" grand number: UP-CI-2022-GDL-06-ING."ABSTRACT Renewable energy utilization is the only suitable solution to diminish the increasing level of greenhouse gas emissions, fuel costs, and energy crisis in the next generation. Out of many renewable sources, solar energy sources that are clean, green, and emission-free have gained wide utilization despite their intermittency nature. Several solar photovoltaic (PV) panels are connected in series-parallel to achieve the energy demand. In such a system, it is possible that each panel operates differently due to uneven temperature and irradiation that results in uniform and partial shading conditions. Thus, a unique and efficient mechanism is required to extract maximum power from uniformly and partially shaded PV systems. Numerous maximum power point tracking (MPPT) methods have been developed to increase the efficiency and lifetime of photovoltaic systems. This study provides a unique, in-depth, and organized review of MPPT methods under four categories: classical, intelligent, optimization, and hybrid techniques. All possible selection benchmarks are considered to do a comprehensive review, which is not deliberated in the existing review literature. Based on the selection benchmarks, the advantages and disadvantages of each MPPT technique under different categories are summarized in tabulated form. To address the research gaps for further investigation in this field, a concise discussion is included at the end. This review article may find an accessible reference for engineers to understand the most useful MPPT method and to undertake extensive research in PV systems.

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Transmission line loss minimization in a power system is an important research issue and it can be achieved by means of reactive power compensation. The unscheduled increment of load in a power system has driven the system to experience stressed conditions. This phenomenon has also led to voltage profile depreciation below the acceptable secure limit. The significance and use of Flexible AC Transmission System (FACTS) devices and capacitor placement is in order to alleviate the voltage profile decay problem. The optimal value of compensating devices requires proper optimization technique, able to search the optimal solution with less computational burden. This paper presents a technique to provide simultaneous or individual controls of basic system parameter like transmission voltage, impedance and phase angle, thereby controlling the transmitted power using Unified Power Flow Controller (UPFC) based on Bacterial Foraging (BF) algorithm. Voltage stability level of the system is defined on the Fast Voltage Stability Index (FVSI) of the lines. The IEEE 14-bus system is used as the test system to demonstrate the applicability and efficiency of the proposed system. The test result showed that the location of UPFC improves the voltage profile and also minimize the real power loss.

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