Some thoughts on the Turkish electricity distribution industry

Over the past decade or so, the electricity industry of the Republic of Turkey (and indeed the world) has undergone profound reform in its structure, ownership and mindset. Increasing public concern about efficiency in the sector has led Turkey to discard the traditional model of a vertically integrated industry subject to cost-based regulation in favor of the unbundling of activities and the introduction of competition where it is possible. The industry has been structurally separated into generation, transmission, distribution and retail segments. The competitive segments of the industry (generation and retail) are planed to progressively expose to competition; the monopoly segments (especially, distribution) are to be reoriented to foster competition. Further, the ownership of the industry is under increasing pressure to move away from the public domain into the private one. The present article not only presents an analysis of the Turkish distribution sector and proposed privatization process but also provides some guidelines for policy makers.     

Universal Current-Mode Active-C Filter Employing Minimum Number of Passive Elements

A universal current-mode active-C filter simultaneously realizing low-pass, band-pass and high-pass responses is proposed. The filter can also realize notch and all-pass responses with interconnection of relevant output currents. The presented filter employs four second-generation current controlled conveyors (CCCIIs) as active elements and only two capacitors as passive elements. The proposed active-C filter can be tuned electronically, and has low element sensitivities.     

Experimental investigation of spray induced gas stratification break-up and mixing in two interconnected vessels

To analyze the effect of containment spray on gas mixing and depressurization, two experiments (ST3_1 and ST3_2) were performed with two interconnected vessels. These experiments were conducted in the frame of the OECD/SETH-2 project using the PANDA facility. The vessels were preconditioned such that a helium-rich layer is formed in the upper section of the first vessel, henceforth referred to as Vessel-1. In the case of the first experiment (ST3_1), the remaining volume of Vessel-1 and the entirety of the second vessel, Vessel-2, were filled with pure steam. For ST3_2, the second experiment presented here, pure steam was replaced with a steam-air mixture instead. Water was injected from the top of Vessel-1 with a spray nozzle projecting downwards. Transient behavior of system pressure, as well as global redistribution of gases is investigated. The results reveal that spray activation is very effective in containment system depressurization. Additionally it is found that the depressurization occurs at a higher rate for the systems containing more steam and less non-condensible gas. The depressurization rate gradually slows down, however, as the steam concentration decreases due to condensation, and non-condensible gases spread over the vessel system. It is also observed that the spray activation initiates the breakup of the helium-rich layer. The composition of the gas atmosphere plays a crucial role in determining the initiation time of the breakup; the presence of large amounts of non-condensible gas such as air delays the beginning of the helium layer breakup by approximately 200 s. The downward component of spray momentum causes the entrainment and the recirculation of the ambient gas atmosphere. Together with the entrainment and condensation effect, spray activation influences the gas mixture density in Vessel-1 and this generates a driving force for inter-compartment flow. As a result of this, an increase of helium-rich gas mixture is observed in the regions far away from the spray, i.e., in Vessel-2.     

麻花钻锥面刃磨参数的确定

根据锥面刃磨法的工作原理,基于LabVIEW软件的开发环境,设计了确定锥顶距A和偏距e的可执行程序。当给定钻头公称直径、半锥角等参数后,即可获得后角和横刃斜角临界值范围内的A、e值及此组A、e所对应的后角、横刃斜角值,同时还可以方便记录、保存合适的刃磨参数以便使用。此程序为高品质后刀面的刃磨提供了一种简捷而高效的方法。     

Changes in quality characteristics during cold storage of shucked mussels (Mytilus galloprovincialis) and selected chemical decomposition indicators

The following chemical changes were observed during the cold storage of mussels for 6 days at 4 °C. Total volatile basic nitrogen (TVB‐N, mg N per 100 g) and trimethylamine values (TMA‐N, mg N per 100 g) were increased from 22.55 and 5.96 mg per 100 g at day 0 to 12.38 and 0.42 mg per 100 g, respectively, at the end of the storage period. The indole value and putrescine concentration were increased from 15.36 µg kg^?1 and 24.7mg kg^?1 to 34.46 µg kg^?1 and 63.86 mg kg^?1, respectively, on the fourth day of storage. The pH was slightly reduced and tyramine and cadaverine were not detected during storage. TVB‐N, TMA‐N and indole value could be selected as decomposition indicators for mussels during their cold storage. Acceptable limits of 15 mg per 100 g for TVB‐N, 3 mg per 100 g for TMA‐N, 35 µg kg^?1 for indole and 60 mg kg^?1 for putrescine are suggested. Sensory and chemical results indicated that the shelf‐life of mussels at 4 °C is limited to 4 days. Copyright © 2005 Society of Chemical Industry     

Small shaking table testing and numerical analysis of free-field site response and soil-structure oscillation under seismic loading

Bulletin of Engineering Geology and the Environment - In this study, the accuracy level of geometric scaling factor (herein, λ = 45) selected for the shaking table test model...     

Development of 3D rock fragmentation measurement system using photogrammetry

ABSTRACT

Run-of-mine fragmentation is an important aspect of mine productivity optimisation, as it affects all mine-to-mill processes. In this study, a 3D rock fragmentation measurement (3DFM) system is proposed that can surmount the limitations of conventional 2D photo-based rock fragmentation measurement methods. To validate the proposed 3DFM performance, a laboratory-based comparison study was conducted using 100 randomly collected rock fragments. Conventional method exhibits relatively low and diffused results than the 3DFM. The proposed 3DFM can be considered as a new particle size distribution measurement method that should efficiently aid in improving mine productivity.     

Cyber victim and bullying scale: A study of validity and reliability

The purpose of this study is to develop a reliable and valid scale, which determines cyber victimization and bullying behaviors of high school students. Research group consisted of 404 students (250 male, 154 male) in Sakarya, in 2009–2010 academic years. In the study sample, mean age is 16.68. Content validity and face validity of the scale was provided via field specialists’ judgment. Confirmatory and exploratory factor analyses were performed for investigation of the factor structure of the scale. As a result of principal component analysis of cyber victim subscale three factors emerged which accounted for the 46.38% of the total variance. Also for cyber bullying subscale, same three factors emerged accounting for the 49.18% of the total variance. Scales with 22 items under 3 factors were tested with confirmatory factor analysis for each victim and bullying variables. Three factors were named as cyber verbal bullying, hiding identity and cyber forgery. Three factors model of scales were found theoretically and statistically fitted after confirmatory factor analysis. For criterion related validity the correlation between cyber victim and bullying scale and Aggression Scale was calculated as .27 and .36, respectively. The internal consistency coefficients calculated for reliability. Cyber victim and bullying scales’ internal consistency coefficients were .89 and split-half coefficients were .79. for both scales. Test-retest reliability for cyber victim .85, for cyber bullying respectively .90 was found. These results demonstrate that the Cyber Victim and Bullying Scale’ is a valid and reliable instrument.     

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.