Active and reactive power sharing and frequency restoration in a distributed power system consisting of two UPS units

A distributed power system consisting of two uninterrupted power supplies (UPS) is investigated in this paper. Parallel operation of the two sources increases the established power rating of the system. One of the sources can supply the system even when the other system is disconnected due to some faults, and this is an important feature. The control algorithm makes sure that the total load is shared between the supplies in accordance with their rated power levels, and the frequency of the supplies are restored to the rated values after the transitions. As the UPSs operate at an optimum power level, losses and faults due to overloading are prevented. The units safely operate without any means of communication between each other. The focus of the work is on the inverter stages of the UPSs. Simulations performed in Matlab Simulink environment have been verified with experimental work via DS1103 controller card.     

Optimal solution to the multinomial selection problem for two alternatives

The multinomial selection problem is to find a stopping policy for repeated independent trials, each of which reports a winner among competing alternatives that has low expected cost and high probability of correct selection (PCS) of the best alternative. In 1959, Bechhofer, Elmaghraby, and Morse formulated the problem as minimizing the worst-case expected number of trials, subject to a lower bound on PCS and upper bound on the maximum number of trials, over all probability vectors outside an indifference zone. For the case of two alternatives, we prove that if one employs a particular probability vector known as the slippage configuration, then a linear program always finds an optimal stopping policy.     

Electropolymerization of Cu-(N,N′-bis(3-methoxysalicylidene)-2-aminobenzylamine) on platinum electrode: Application to the electrocatalytic reduction of hydrogen peroxide

The complex of copper (II) with N,N′-bis(3-methoxysalicylidene)-2-aminobenzylamine (H₂L) was synthesized and characterized by elemental analysis, magnetic susceptibility, UV–vis. and FT-IR spectroscopy. The results showed that the tetradentate ligand coordinated to the Cu(II) ion through the azomethine nitrogen and phenolic oxygen atoms. The prepared complex [CuL] was electropolymerized on platinum electrode surface in a 0.1 mol dm⁻³ solution of lithium perchlorate in acetonitrile by cyclic voltammetry between 0 and 1.6 V vs. Ag/Ag⁺. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), conductance measurements, FT-IR and SEM were used to characterize polymer film of Cu(II) complex. The reduction of hydrogen peroxide on poly[CuL] has been investigated mainly in phosphate buffer medium (pH 7.2), between 0 and −0.8 V versus Ag/Ag⁺ at a scan rate 0.1 V s⁻¹.     

Effects of differences in diet and seasonal changes on the fatty acid composition in fillets from farmed and wild sea bream (Sparus aurata L.) and sea bass (Dicentrarchus labrax L.)

The effects of dietary fatty acids and seasonal variation on the fatty acid profiles of farmed and wild sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) were determined by analysis of their fillets. Farmed sea bream and sea bass were fed on the same commercial feeds all year. Fatty acid profiles in the fillets reflected the fatty acid profiles of the commercial feeds. The predominant fatty acids in the trial feeds, fillets of farmed and wild sea bream and sea bass were 16:0, 18:1n‐9, 18:2n‐6, 20:5n‐3 and 22:6n‐3. The fatty acid profiles in the fillets of farmed sea bream and sea bass did not differ (P > 0.05) except in the winter season compared with those of their wild counterparts. However, the content of eicosapentaenoic acid (20:5n‐3), docosahexaenoic acid (22:6n‐3) in the fillets of the farmed and wild sea bass were significantly (P < 0.05) higher than the farmed and wild sea bream. The wild sea bream had significantly (P < 0.05) higher total saturated fatty acid and monounsaturated fatty acid (MUFA) levels, and lower total n‐6 and n‐3 polyunsaturated fatty acid (PUFA) levels in winter than in the summer and spring seasons. Similarly, in the fillets of wild sea bass, total n‐3 PUFA levels were significantly (P < 0.05) lower, and the MUFA levels were higher in winter than in the other seasons. These results indicate that the farmed fish fillets were good sources of n‐3 PUFA in each of the three seasons. However, wild fish were good sources of n‐3 PUFA in the spring and summer.     

Characterization of activated carbon produced from almond shell and hazelnut shell

Ammonium chloride-impregnated and untreated almond shell and hazelnut shell samples were carbonized in a flow of nitrogen at relatively low temperatures. Pore structure characterization and sorption capacities of activated carbons prepared from shells of almond and hazelnut indicated that treatment with NH₄Cl increased the total surface area and improved sorption characteristics. Chemical activation carried out at 350°C gave products with surface area values above 500 m² g^?1. On the other hand, the surface area values observed for the products obtained from untreated raw materials were about half of this value. The surface area of products obtained from NH₄Cl-impregnated samples reached values of over 700 m² g^?1 when the carbonization temperature was increased 700°C.     

Carrageenin granuloma in the plaice (Pleuronectes platessa); a histopathological study of chronic inflammation in a teleost fish

The protein component of tissue thromboplastib (Factor III) from human brain was purified by extraction of a microsomal fraction with sodium deoxycholate, gel filtration of the extract on Sephadex G-100 and preparative polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. The product, apoprotein III, was homogeneous by anayltical polyacrylamide-gel electrophoresis, and it induced monospecific antibodies in rabbits and goat as shown by immunodiffusion and immunoelectrophoresis. Amino acid- and carbohydrate-analysis data for apoprotein III are presented. The carbohydrate moiety of the protein consists of fucose, mannose, galactose, N-acetylglucosamine and N-acetylneuraminate, amounting to a total content of 6.3g/100g. The apoprotein alone had no procoagulant activity. When Factor III was reconstituted by combining the pure apoprotein with a purified lipid fraction from the deoxycholate extract of crude Factor III, a high and optimal procoagulant activity was obtained at a phospholipid/protein ratio of 1.1g/g. Phosphatidylethanolamine alone had a weak but significant ability to restore activity, whereas phosphatidylcholine and phosphatidylserine separately had almost none. Two-component mixtures were on average more effective, and three-component mixtures far more effective, than the single phospholipids. The inclusion of a small amount of phosphatidylserine was very important for high activity.     

Lignin‐derived heteroatom‐doped porous carbons for supercapacitor and CO2 capture applications

The present study reports the economic and sustainable syntheses of functional porous carbons for supercapacitor and CO₂ capture applications. Lignin, a byproduct of pulp and paper industry, was successfully converted into a series of heteroatom‐doped porous carbons (LHPCs) through a hydrothermal carbonization followed by a chemical activating treatment. The prepared carbons include in the range of 2.5 to 5.6 wt% nitrogen and 54 wt% oxygen in its structure. All the prepared carbons exhibit micro‐ and mesoporous structures with a high surface area in the range of 1788 to 2957 m² g^?1. As‐prepared LHPCs as an active electrode material and CO₂ adsorbents were investigated for supercapacitor and CO₂ capture applications. Lignin‐derived heteroatom‐doped porous carbon 850 shows an outstanding gravimetric specific capacitance of 372 F g^?1 and excellent cyclic stability over 30,000 cycles in 1 M KOH. Lignin‐derived heteroatom‐doped porous carbon 700 displays a remarkable CO₂ capture capacity of up to 4.8 mmol g^?1 (1 bar and 298 K). This study illustrates the effective transformation of a sustainable waste product into a highly functional carbon material for energy storage and CO₂ separation applications.     

Implementation of an electrolysis system with DC/DC synchronous buck converter

A synchronous buck DC–DC converter that can be used to produce hydrogen through electrolysis by using the energy generated from renewable energy sources has been designed and implemented. The reason for selecting this topology is that the voltage level at the output of renewable sources, such as solar cells and storage batteries, is about 12 V DC, and the voltage level required for electrolysis is about 2 V DC. Traditional buck converters have low efficiencies at low output voltages since the voltage drops on the components are comparable to the output voltage. The converter has been designed and tested at 25 A output current. Two different electrodes were used for electrolysis and the effect of electrode opening on the operation was observed. In addition, the stability analysis of non-linear electrolysis system load has been performed.     

Recent progress in CFD for naval architecture and ocean engineering

An overview is provided of CFDShip-Iowa modeling, numerical methods and high performance computing(HPC), including both current V4.5 and V5.5 and next generation V6. Examples for naval architecture highlight capability and needs. High fidelity V6 simulations for ocean engineering and fundamental physics describe increased resolution for analysis of physics of fluids. Uncertainty quantification research is overviewed as the first step towards development stochastic optimization.