Planar antenna pattern nulling using differential evolution algorithm

Differential evolution algorithm is used for the pattern synthesis of planar antenna arrays with prescribed pattern nulls by position-only and position-amplitude optimization. The position-only optimization for a planar array allows null synthesis in any prescribed direction. For planar antenna array thinning it is necessary to use position-amplitude optimization for problems involving more than two nulls.     

A paper on the unsettled question of Turkish electricity market: Balancing and settlement system (Part I)

Turkish electricity market law (EML) came into force in 2001 aiming at establishing a financially strong, stable, transparent and competitive electricity market based on bilateral contracts. Also, a balancing and settlement system (BSS) was put into practice in November 2004 to create a market where uncontracted generation can be traded, and actual implementation of the BSS started on August, 1st 2006 following a 21-month virtual implementation period. However, BSS has always been criticized from its beginning as transferring excessive profits to private generation companies. The present paper analyzes the implementation of BSS and argues that current BSS not only undermines the healthy development of the electricity market in Turkey but also prevents power investments due to uncertainties it created. It concludes that since the inconsistency between the objectives of EML and results of BSS in practice is obvious, Turkish policy makers need to modify current electricity market policy in line with suggestions presented in the paper.     

Effect of biogenic substrate concentration on the performance of sequencing batch reactor treating 4-CP and 2,4-DCP mixtures

Effect of a biogenic substrate (peptone) concentration on the performance of sequencing batch reactor (SBR) treating 220 mg/l 4-chlorophenol (4-CP) and 110 mg/l 2,4-dichlorophenol (2,4-DCP) mixtures was investigated. In this context, peptone concentration was gradually decreased from 300 mg/l to null in which chlorophenols were fed to the reactor as sole carbon and energy sources. By this way, the effect of peptone concentration on observed yield coefficient (Y), biomass concentration, chlorophenols and COD removal performances were investigated. Decreasing peptone concentration accompanied with lower biomass concentration led to increase in peak chlorophenol and COD concentrations within the reactor during each SBR cycle. This, in turn, caused noteworthy declines in the removal rates as chlorophenol degradations followed Haldane substrate inhibition model. Also, increased peak chlorophenol concentrations led to the accumulation of 5-chloro-2-hydroxymuconic semialdehyde (CHMS), which is -meta cleavage product of 4-CP. Despite the decreased removal rates, complete chlorophenols and CHMS degradation, in addition to high COD removal efficiencies (>90%), were observed for all studied conditions, even chlorophenols were added as sole carbon and energy sources. Another significant point is that 2,4-DCP at slightly elevated concentrations (>20 mg/l) within the reactor caused a strong competitive inhibition on 4-CP degradation. In SBR, feeding the influent to the reactor within a certain period (i.e. filling period) provided dilution of coming wastewater, which decreased the chlorophenols concentrations to which microorganisms were exposed. Therefore, use of SBR may help to avoid both self and competitive inhibitions in the treatment of 4-CP and 2,4-DCP mixture especially in the presence high biogenic substrate concentrations. In addition, isolation and identification studies have indicated that Pseudomonas sp. and Pseudomonas stutzeri were dominant species in the acclimated mixed culture.     

Comment on “realization of series and parallel R-L and C-D impedances using single differential voltage current conveyor”

The comment is related to the recently published paper given in [1] dealing with the implementation of series and parallel R-L and C-D impedances using a single differential voltage current conveyor (DVCC). Nevertheless, straightforward analysis of the circuit in Fig. 3(b) of [1] and also given in Fig. 1 shows that it has a problem because it makes its input voltage V _in = 0. Therefore, it can not realize parallel (–L)–(–R) simulator as claimed in [1]. Alternatively, a circuit given in Fig. 2 for realizing parallel (–L)–(–R) simulator employing a single minus-type DVCC (DVCC–) and a minimum number of passive components is proposed. The introduced circuit employs a grounded capacitor, and requires no critical component matching constraints thus it is suitable for fully integrated circuit technology. If plus-type DVCC (DVCC+) is replaced instead of the DVCC–, this proposed simulator can realize parallel (L)–(R) simulator. Fig. 1 The circuit proposed in Fig. 3(b) of [1]

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Fig. 2 Presented circuit for realizing parallel (+L)–(+R) and parallel (L)–(R) simulators depending on the type of the DVCC

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Effects of essential oils on the survival of Salmonella Enteritidis and Listeria monocytogenes on fresh Atlantic salmons (Salmo salar) during storage at 2 ± 1 °C

In this study, the effects of coriander, garlic, rosemary, and orange peel oils on the survival of Salmonella Enteritidis and Listeria monocytogenes were examined 2 ± 1 °C during storage of inoculated fresh Atlantic salmon samples (96 hr). At the end of storage population decrease in Salmonella Enteritidis was significantly lower (p < .05) in the essential oil groups compared with control group. Salmonella Enteritidis count of rosemary oil treated group was higher than (p < .05) other groups (coriander, garlic, and orange peel oils) at the end of storage. Essential oils decreased the population of L. monocytogenes while the population in untreated samples were higher at the end of storage period (p < .05). Results of this study indicated that treatment of salmon fish samples with essential oils may be an effective natural antimicrobial application to control Salmonella Enteritidis and L. monocytogenes.

Practical applications

In the present study, it was concluded that essential oils had an antimicrobial effect Salmonella Enteritidis and Listeria monocytogenes. Use of essential oils during storage of fish or fish products may play an important role against Salmonella Enteritidis and L. monocytogenes. Essential oils are easily applicable and a cheaper method. The results of this experiment propose that addition of essential oils to fish flesh can be recommended to seafood processors and fish market retailers.