Biodiesel from the perspective of Turkey: Past, present and future

WOS: 000325830900028Energy is an indispensable factor of today's developed and developing societies. However, supplying most of the energy need through nonrenewable fossil fuels has come to the threatening position for both the energy demand and the sustainable development in the future. For this reason, most of the developed countries have started to reduce the foreign dependency in order to stabilize their economies and head towards more environmental and renewable resources. Particularly, economic fluctuation and environmental damages depending on the oil need which increases day by day raise the importance of biofuels. Biodiesel developed as an alternative of diesel fuel has reached up to 17.6 billion liters of production amounts over the last 20 years. It is predicted that this increase would be much more rapid in the next decade and reach up to 42 billion liters. EU, Argentina, Brazil, Malaysia and the USA supply the 93% of the biodiesel production of the world. Turkey, which is 78% foreign-dependent in terms of energy and imports its 93% of oil need, supported biodiesel production in 2000s in order to close its current deficit and prevent oil's environmental damages. However, the desired aims could not be achieved and many biodiesel facilities were shut down. Along with the amendments in the legislation of petroleum products by the end of 2011, it is aimed that the biodiesel sector would be boosted through arousing interest in biodiesel again. (C) 2013 Elsevier Ltd. All rights reserved

Experimental Comparison of Biogas and Natural Gas as Vibration, Emission, and Performance in a Diesel Engine Converted to a Dual Fuel

WOS: 000587750600004Biogas, natural gas, and their usage in the diesel engine will be important in the future. For this purpose, the effects of biogas on engine performance, emissions, and engine vibrations of the diesel engines with dual fuel system are investigated in comparison with natural gas. It has also been included in evaluating the deformation of the engine oil due to hydrogen sulfide combustion reactions. in this study, a constant speed, naturally aspirated, and direct injection of the diesel engine with volume of 2.5 liter has been converted into a dual fuel system that can be included in gas fuels. in order to determine engine performance, exhaust emissions, engine vibration, and noise, the tests were carried out at load stages of 5, 10, 15, 20, and 25 kW and at a constant speed of 1500 rpm. the experiments were first performed in a mono operation condition of the conventional diesel fuel. Subsequently, tests were repeated under natural gas/diesel and biogas/diesel dual fuel operation conditions, respectively. As a result of the tests, it was observed that the vibration amount decreased and the noise emission was reduced by 3.5% in all stages where biogas was used as the main fuel. Depending on fuel or operation system change, no significant change was observed in cylinder block, cylinder heat, exhaust, and intake manifold temperature. the exhaust gas temperature is measured to be lower because of the carbon dioxide (CO2) content in the biogas. When approaching from the point view of engine emissions, it was determined that the carbon monoxide (CO) emission increased at all engine loads while a decrease of 50% in oxides of nitrogen (NOx) emission occurred

Przegląd materiałów i struktur pochłaniających promieniowanie radarowe

The development of technologies that can rival the devices used by other countries in the defense industry, and more importantly, can disable their devices is becoming more critical. Radar absorber materials (RAM) make the detection of the material on the radar difficult because of absorbing a part of the electromagnetic wave sent by the radar. Considering that radar is one of the most important technologies used in the defense industry, the production of non-radar materials is vital for all countries in the world. Covering a gun platform with radar absorber material reduces the radar-cross-sectional area (RCA) value representing the visibility of that platform on the radar. This review aims to present the electromagnetic principles and developed Radar Absorbent Materials (RAM) during decades from the 1960s. The frequency range 8-12 GHz in the electromagnetic spectrum is named the microwave region and used in airport radar applications. Revised basis of electromagnetic theory and defined by a variety of absorbent materials and some design classification types and techniques are described in this article.Coraz większego znaczenia nabiera rozwój technologii mogących konkurować z produktami przemysłu obronnego używanymi przez inne kraje oraz, co istotniejsze, uniemożliwiać prawidłowe działanie tych produktów. Materiały pochłaniające promieniowanie (RAM – radiation-absorbent material) utrudniają wykrycie obiektu przez radar, absorbując część wiązki elektromagnetycznej wysłanej przez to urządzenie. Biorąc pod uwagę to, że radiolokacja stanowi jedną z najistotniejszych technologii stosowanych w przemyśle obronnym, produkcja materiałów zakłócających jej skuteczność ma kluczowe znaczenie dla wszystkich krajów świata. Pokrycie platformy bojowej materiałem pochłaniającym promieniowanie ogranicza skuteczną powierzchnię odbicia (SPO), od której zależna jest widoczność tej platformy na radarze. Niniejszy artykuł ma na celu przedstawienie zasad elektromagnetyzmu oraz rozwoju materiałów pochłaniających promieniowanie począwszy od lat sześćdziesiątych XX w. Fale elektromagnetyczne o częstotliwości 8-12 GHz określane są jako mikrofale i mają zastosowanie w urządzeniach radiolokacyjnych lotnisk. W artykule przedstawiono uaktualnione podstawy teorii elektromagnetycznej, zdefiniowano różnorodne materiały pochłaniające oraz przedstawiono niektóre typy i techniki