Sustainable energy production and consumption in Turkey: A review

In this century, energy has been the driving force of the global economy and it will, for sure, continue to be one of the most important element for the sustainable socio-economic development for the coming centuries. Therefore, energy producers and governors have a vital duty to provide enough energy in good quality continuously with low cost for the sustainable development. The subject of energy production and energy politics in Turkey generally comes at first privilege. Ahead of the 21st century, Turkish energy diplomacy started to affect the future course of Turkey’s relations with the Eurasian countries as well as the Western countries. This paper describes energy production and consumption strategies in Turkey and criticizes Turkish energy policies. If the present pattern of energy production and consumption in Turkey is maintained, there will be serious problems to meet future energy demands due to shortages of resources and low financial inputs, combined with the environmental care for the country. As a result, major components of Turkey’s strategy for sustainable development should include changing the present energy production and consumption patterns, expanding energy sources and the structure of power production, and creating an energy structure that is less or not at all risky to the environment.     

Impact of Parameter Variations on Circuits and Microarchitecture

Parameter variations, which are increasing along with advances in process technologies, affect both timing and power. Variability must be considered at both the circuit and microarchitectural design levels to keep pace with performance scaling and to keep power consumption within reasonable limits. This article presents an overview of the main sources of variability and surveys variation-tolerant circuit and microarchitectural approaches     

Realization of Current-Mode Third Order Butterworth Filters Employing Equal Valued Passive Elements and Unity Gain Buffers

This paper describes current-mode third-order Butterworth filter topologies realized with unity gain active elements and minimum number of passive components. All capacitors and resistors are equal valued. The core of the circuit realizes HP, BP and LP functions easily. The filter exhibits high output impedance. Experimental results are included to verify theory.     

Effects of surface-finishing forms and cement-filling on porous dimension limestone deterioration in cold regions

This work studies the influences of both surface-finishing forms and cement-filling on the durability of dimension limestone in cold regions. Freeze-thaw cycles, aqueous saline solution and their interactions with surface-finishing forms and cement-filling on stones were investigated for two types of porous limestone, Caribbean and Pewter Blend. Both deionised water and saline water composed of 20% NaCl by weight were used, and 28 freeze-thaw cycles were applied to the samples. The change in dry weight, porosity, and Böhme abrasion loss value was obtained for all test samples. It was observed that two types of porous limestone with cement-filling and different types of surface-finishing were influenced to different extents by freeze-thaw and salt. Experiments showed that stones to be used outdoors in cold regions should have relatively low initial porosity and that they should be fine-finished and cement-filled; these modifications to the stones will maximise the benefit received from the stones.     

Clozapine Increases Nestin Concentration in the Adult Male Rat Hippocampus: A Preliminary Study

Patients with schizophrenia, and rodent models of the disease, both exhibit suppressed neurogenesis, with antipsychotics possibly enhancing neurogenesis in pre-clinical models. Nestin, a cytoskeletal protein, is implicated in neuronal differentiation and adult neurogenesis. We hypothesized that schizophrenia pathogenesis involves nestin downregulation; however, few studies have related nestin to schizophrenia. We assessed nestin protein concentration, prepulse inhibition (PPI), and social interaction in the MK-801 model of schizophrenia, with or without antipsychotic (clozapine) treatment. Adult male Sprague–Dawley rats were intraperitoneally administered saline or MK-801 (0.1 mg/kg) to produce a schizophrenia-like phenotype, with concomitant subcutaneous injections of vehicle or clozapine (5 mg/kg). PPI was assessed on days 1, 8, and 15, and social interaction was assessed on day 4. Hippocampus tissue samples were dissected for Western blotting of nestin concentration. MK-801 alone did not alter nestin concentration, while clozapine alone enhanced hippocampal nestin concentration; this effect was not apparent in animals with MK-801 and clozapine co-administration. MK-801 also produced schizophrenia-like PPI disruptions, some of which were reversed by clozapine. Social interaction deficits were not detected in this model. This is the first report of clozapine-induced enhancements of hippocampal nestin concentration that might be mediated by NMDA receptors. Future studies will explore the impact of neurodevelopmental nestin concentration on symptom onset and antipsychotic treatment.     

Biodegradability of slaughterhouse wastewater with high blood content under anaerobic and aerobic conditions

In this work, the biodegradability of wastewater from a slaughterhouse located in Ke?an, Turkey, was studied under aerobic and anaerobic conditions. A very high total COD content of 7230 mg dm^?3 was found, due to an inefficient blood recovery system. Low BOD₅/COD ratio, high organic nitrogen and soluble COD contents, were in accordance with a high blood content. A respirometry test for COD fractionation showed a very low readily biodegradable fraction (S_S) of 2%, a rapidly hydrolysable fraction (S_H) of 51%, a slowly hydrolysable fraction (X_S) of 33% and an inert fraction of 6%. Kinetic analysis revealed that hydrolysis rates were much slower than these of domestic sewage. The results underlined the need for an anaerobic stage prior to aerobic treatment. Tests with an anaerobic batch reactor indicated efficient COD degradation, up to around 80% removal. Further anaerobic degradation of the remaining COD was much slower and resulted in the build up of inert COD compounds generated as part of the metabolic activities in the anaerobic reactor. Accordingly, it is suggested that an appropriate combination of anaerobic and aerobic reactors would have to limit anaerobic degradation to around 80% of the tCOD and an effluent concentration above 1000 mg dm^?3, for the optimum operation of the following aerobic stage. © 2003 Society of Chemical Industry     

Intermodulation Distortion in CMOS Attenuators and Switches

Gain control elements are widely used in communication systems both to limit the incident power to the circuitry and to control the amplitude of the transmitted signal. Attenuators are one way of controlling the signal amplitude. The distortion performance of common CMOS attenuator topologies is investigated in this work. CMOS device equations that model the device in different regions of operation and which also model short channel effects are used for calculating distortion performance. Calculated distortion is compared with simulation results and experimental data, and qualitative explanations of the distortion curves as well as the deviation between different sources of data are given. Potential improvements in linearity performance of attenuators via circuit design techniques have also been discussed     

Entropy generation through hexagonal cross‐sectional duct for constant wall temperature in laminar flow

Second law analysis of heat transfer in laminar flow for hexagonal cross‐section duct was analysed analytically. Geometrical effect of hexagonal duct was considered. The variation of total entropy generation was studied along the duct length. As a working fluid water and unused engine oil were used to compare the effect of fluid in the duct. Results were compared with circular cross‐section duct. It is found that the non‐dimensional entropy generation in a hexagonal cross‐section duct can be as high as a factor of four than that for a circular duct. Further, the unused engine oil gives up to about ten times lower non‐dimensional entropy generation values than that of water but needs about ten times more pumping power to heat transfer ratio. Copyright © 2004 John Wiley & Sons, Ltd.     

Finite element simulation of quench hardening

In this study, an efficient finite element model for predicting the temperature field, volume fraction of phases and the evolution of internal stresses up to the residual stress states during quenching of axisymmetrical steel components is developed and implemented. The temperature distribution is determined by considering heat losses to the quenching medium as well as latent heat due to phase transformations. Phase transformations are modelled by discretizing the cooling cuves in a succession of isothermal steps and using the IT-diagrams. For diffusional transformations both Scheil's additivity method and Johnson-Mehl-Avrami equation are used, while Koistinen-Marburger equation is employed for martensitic transformation. Internal stresses are determined by a small strain elasto-plastic analysis using Prandtl-Reuss constitutive equations. Considering long cylinders, a generalized plane strain condition is assumed. The computational model is verified by several experimental measurements and by comparison with other known numerical results. Case studies are performed with St50, Ck45 and C60 type of solid and hollow steel components. The complete data and result sets provided for the verification examples establish a basis for benchmark problems in this field.