Control of an Ultracapacitor-Based Energy Storage System for Source and Load Support Applications

This paper presents a simple pulse width modulation algorithm for control of an ultracapacitor based energy storage system used for source and load support applications. As opposed to dual loop control philosophy that is widely used for backup applications, this paper presents a simple single loop current control that is only useful for controlling the ultracapacitor based DC/DC converters used in source and load support applications. The proposed PWM blocking method necessitates the DC/DC converter to operate in five states and takes into consideration the essential operational limits associated with the ultracapacitors. The performance of the proposed algorithm is verified experimentally using a 24 V laboratory prototype setup. Further, the shortcomings of dual loop control when applied to source and load support applications are demonstrated

Susceptor-Assisted Rapid Microwave Sintering of Al-Kaolin Composite in a Single-Mode Cavity

The present research addresses the low-temperature sintering of 4% kaolin clay reinforced aluminium composite using susceptor-aided microwave sintering at 2.45 GHz frequency. Kaoline clay the naturally available mineral in the north-eastern regions of india. The study aims to convert this kaoline clay into the value added product with enhanced mechanical properties. The Al-x% Kaolin (x = 2, 4, 6, 8, 10) composite was fabricated through the powder metallurgy process by the application of 600 MPa compaction pressure. The composite corresponding to optimum ultimate tensile strength (U.T.S) was subjected to single-mode cavity microwave-assisted sintering by varying the sintering temperatures as 500°C, 550°C and 600°C. The effect of incorporating kaolin clay on the dielectric characteristics of composite powders, as well as the effect of sintering temperature on the microstructural changes and mechanical characteristics of Al-4%Kaolin composites were also examined. Results concluded that the addition of 4 wt% kaolin powder improves the dielectric characteristics of the composite powder. The maximum Hardness. Compression strength and U.T.S of 97 Hv, 202 MPa and 152 MPa respectively achieved for the Al-4% Kaolin composite sintered at 550°C. The higher fracture toughness of 9.56 Ma. m1/2 reveals the ductile fracture for the composite sintered at 550°C

Optimal trade credit and replenishment policies for non-instantaneous deteriorating items

The present study presents a fuzzy inventory model for non-instantaneous deteriorating items under conditions of permissible delay in payments. In the current paper, we incorporate the condition in which, the supplier accepts the partial payment at the end of the credit period and the reaming amount after that period under the term and condition. Here, the demand rate is a function of the selling price. Also, it is assumed that shortages are allowed and are fully backlogged. The present paper also considers that the interest earned (IE) on the fixed deposit amount, i.e., revenue generated by fulfilling the shortage, balance amount, after settling the account is higher than that of usual interest rate (Ie). Hence, the objective of this study is to determine the retailer’s optimal policies that maximize the total profit. Also, some theoretical results are obtained, which shows that the optimal solution not only exists, it is unique also. The impact of the new proposed credit policy is investigated on the optimality of the solution for the non-instantaneous deteriorating products. The validation of the proposed model and its solution method is demonstrated through the numerical example. The results indicate that the inventory model, along with the solution method, provides a powerful tool to the retail managers under real-world situations. Results demonstrate that it is essential for the managers to consider the inclusion of new proposed credit policy significantly increases the net annual profit

Processing and evaluation of nano SiC reinforced aluminium composite synthesized through ultrasonically assisted stir casting process

Aluminium composites were synthesized through an ultrasonically assisted stir casting method by reinforcing 0.5 wt%SiC, 1.0 wt%SiC, 1.5 wt%SiC and 2.0 wt%SiC nanoparticles. Ultrasonication was carried out to the composite melt to refine the grain size and to achieve uniform nano-SiC dispersion in the aluminium matrix. Scanning electron microscopy (SEM) reveals the uniform dispersion of nano-SiC particles in the 0.5 wt%, 1.0 wt% and 1.5 wt% SiC reinforced compose. However, the X-Ray Diffraction (XRD) peaks confirm the Al2Cu intermetallic phases in the Al- 2.0 wt% SiC composite. The mechanical properties of the synthesized composites were significantly enhanced with the incorporation of SiC reinforcements and the maximum hardness and ultimate tensile strength (U.T.S) of 163 BHN and 431 MPa was attained for 1.5 wt% SiC reinforced composite. Nevertheless, the generated brittle agglomeration at 2.0 wt% SiC reinforcements decreases the mechanical properties of the composite due to the variation of thermal expansion coefficients between the matrix and the agglomerations. The yield strength of the fabricated Al– SiC composites was analyzed through different strengthening mechanisms. Results concluded that the yield strength contribution due to thermal mismatch is more influenced followed by the Orowan strengthening and grain refinement strengthening mechanism. In addition to this, the contribution of the strengthening mechanisms was found to be increased with the addition of SiC nanoparticles. Fractography investigation for the fractured tensile specimens reveals the ductile fracture for unreinforced aluminium and brittle fracture for the SiC-reinforced composites due to the presence of cleavage texture of the fractured surfaces of Al–SiC nanocomposites

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