Turkish support to Kyoto Protocol: A reality or just an illusion

The long-term increase in Earth's temperature is known as the global warming or the greenhouse effect. Taking into account the fact that the ice age only involved a global temperature variation of around 4 °C, it is clear climate change is arguably one of the greatest environmental threats the world is facing today. The impacts of disruptive change leading to catastrophic events such as storms, droughts, sea level rise and floods are already being felt across the world. In this context, the signing of the Kyoto Protocol in 1997 has been argued to be a historic step in reversing the inexorable increase in the emission of the greenhouse gases. The primary achievement of the Protocol has been so-called commitment of countries referred in the Annex I of the Protocol to reduce their emission of GHGs some 5% below their country specific 1990 level. On February 5, 2009, Turkish Parliament ratified an agreement to sign the Kyoto Protocol after intense pressure from both the European Union and international environmental organizations; however, so far it has not taken any step to bring about real reductions in emissions. In short, Turkey simply signed but ignored the Protocol. Present paper investigates Turkish position vis-à-vis Kyoto Protocol and critically questions Turkish policies in that area.     

Modeling of hydrogen production with a stand-alone renewable hybrid power system

Hydrocarbon resources adequately meet today’s energy demands. Due to the environmental impacts, renewable energy sources are high in the agenda. As an energy carrier, hydrogen is considered one of the most promising fuels for its high energy density as compared to hydrocarbon fuels. Therefore, hydrogen has a significant and future use as a sustainable energy system. Conventional methods of hydrogen extraction require heat or electrical energy. The main source of hydrogen is water, but hydrogen extraction from water requires electrical energy. Electricity produced from renewable energy sources has a potential for hydrogen production systems. In this study, an electrolyzer using the electrical energy from the renewable energy system is used to describe a model, which is based on fundamental thermodynamics and empirical electrochemical relationships. In this study, hydrogen production capacity of a stand-alone renewable hybrid power system is evaluated. Results of the proposed model are calculated and compared with experimental data. The MATLAB/Simscape^® model is applied to a stand-alone photovoltaic-wind power system sited in Istanbul, Turkey.     

Improvement of PEMFC performance with Nafion/inorganic nanocomposite membrane electrode assembly prepared by ultrasonic coating technique

Membrane electrode assemblies with Nafion/nanosize titanium silicon dioxide (TiSiO₄) composite membranes were manufactured with a novel ultrasonic-spray technique and tested in proton exchange membrane fuel cell (PEMFC). Nafion/TiO₂ and Nafion/SiO₂ nanocomposite membranes were also fabricated by the same technique and their characteristics and performances in PEMFC were compared with Nafion/TiSiO₄ mixed oxide membrane. The composite membranes have been characterized by thermogravimetric analysis, scanning electron microscopy, X-ray diffraction, water uptake, and proton conductivity. The composite membranes gained good thermal resistance with insertion of inorganic oxides. Uniform and homogeneous distribution of inorganic oxides enhanced crystalline character of these membranes. Gas diffusion electrodes (GDE) were fabricated by Ultrasonic Coating Technique. Catalyst loading was 0.4 mg Pt/cm² for both anode and cathode sides. Fuel cell performances of Nafion/TiSiO₄ composite membrane were better than that of other membranes. The power density obtained at 0.5 V at 75 °C was 0.456 W cm⁻², 0.547 W cm⁻², 0.477 W cm⁻² and 0.803 W cm⁻² for Nafion, Nafion/TiO₂, Nafion/SiO₂, and Nafion/TiSiO₄ composite membranes, respectively.     

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.     

The effect of high hydrostatic pressure on the microbiological, chemical and sensory quality of fresh gilthead sea bream (Sparus aurata)

The effect of different temperature/time/pressure high hydrostatic pressure (HHP) treatment on quality and shelf life of sea bream were studied. Different high-pressure treatments (at 3, 7, 15 and 25 °C, 5–10 min and 220, 250 and 330 MPa) were tested to establish the best processing conditions for quality of sea bream. The effect of the process on the quality of the sample was examined by colour, trimethylamine nitrogen and thiobarbituric acid number analysis. Based on the results of the parameter, the best combinations of HHP treatments were determined as 3 °C/5 min/250 MPa–15 °C/5 min/250 MPa for sea bream. The effects of this combination treatment on sensory, chemical and microbiological properties of sea bream stored at 4 °C were studied. The results obtained from this study showed that the shelf life of untreated and HHP treated stored in refrigerator, as determined by overall acceptability of sensory and microbiological data, is 15 days for untreated sea bream and 18 days for treated sea bream at 3 °C/5 min/250 MPa and at 15 °C/5 min/250 MPa treated sea bream.     

A Novel CMOS-Based Voltage-Mode First-Order Phase Shifter Employing a Grounded Capacitor

In this paper, a voltage-mode (VM) topology for providing first-order all-pass filter responses is suggested. The proposed circuit is composed of a smaller number of components when compared to earlier ones, as it employs only three CMOS transistors, a grounded capacitor which is advantageous in integrated circuit (IC) processes, and two resistors. Computer simulation results, using the SPICE program, are given to exhibit the performance. A second-order low-pass filter employing only grounded capacitors which are canonical in number is given as one of the applications of the presented non-inverting first-order all-pass filter topology.     

Determination of acceptable operating cost level of nuclear energy for Turkey's power system

Generally, it is very difficult to assess the true operating cost of an electrical power unit in the countries where there is little or no operational experience. Since Turkey has no experience on operating a nuclear unit, operating costs of a nuclear unit is uncertain for use in generation expansion planning (GEP). Furthermore, there is a disagreement of whether it is cheap or not. In this study, an acceptable level of operating cost of nuclear units is determined for Turkey's power system. It is aimed to find a numerical value for nuclear operating cost at which nuclear is able to compete with other energy sources. Seven types of units are chosen as candidate units to the power system. Mixed-integer programming (MIP) is used as a mathematical model of generation expansion planning. The model consists of the cost function that minimizes the construction and operating costs and the reliability constraints. Adaptive simulated annealing genetic algorithm (ASAGA) is used for optimization algorithm to determine the types, times, and number of candidate units which meet forecasted demand within a pre-specified reliability criterion over the planning horizon from 2006 to 2025. In the case studies, a high level of nuclear energy operating cost is taken and then the cost is gradually lowered. Optimizations are made for each level of nuclear operating costs within four different scenarios and the quantities of nuclear capacity selected by optimizations are recorded. It is determined that, nuclear energy is able to compete with other energy sources when the operating cost is less than 210$/kWh yr or 2.4cent/kWh.     

Effects of various sulphuring methods and storage temperatures on the physical and chemical quality of dried apricots

The effects of different sulphuring methods, i.e. sulphuring by “burning the elemental sulphites (BES),” “SO₂ gas from liquified SO₂ tank (SG)” and “dipping into sodium metabisulphite solution (DSM)” on the colour (brown colour formation and carotenoid degradation) and the loss of SO₂ in apricots from Hac?halilo?lu and Kabaa?? varieties stored at 5, 20 and 30 °C for a year were investigated. There were significant effects of variety, sulphuring method and especially storage at 30 °C on the brown colour formation and loss of SO₂ (P < 0.05). As storage temperature–time increased, β-carotene content decreased. Sulphuring methods and variety did not show significant effect on β-carotene content (P > 0.05). The changes in L^∗, b^∗ and C^∗ values were directly associated with β-carotene content and browning values. The most suitable method for all samples, except for Hac?halilo?lu variety stored at 30 °C (BES), is SG, because the samples retained their attractive golden yellow colour during storage.     

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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Comments on “SITO electronically tunable high output impedance current-mode universal filter”

A comment related to the recently published current-mode universal filter, is given. In this comment, it is claimed that this filter is derived from the previously published one without any significant change.