Istanbul Technical University

About: Istanbul Technical University is a education organization based out in Istanbul, Turkey. It is known for research contribution in the topics: Fuzzy logic & Large Hadron Collider. The organization has 12889 authors who have published 25081 publications receiving 518242 citations. The organization is also known as: İstanbul Teknik Üniversitesi & Technical University of Istanbul.

One-Component Bimolecular Photoinitiating Systems, 2†

Abstract: The compounds 2-thioxanthone-thioacetic acid and 2-(carboxymethoxy)thioxanthone, bimolecular photoinitiators for free radical polymerization, are synthesized and characterized. Their capability to act as initiators for the polymerization of methyl methacrylate was examined. The postulated mechanism is based on the intermolecular electron-transfer reaction of the excited photoinitiator with the sulfur or oxygen atom of the ground state of the respective photoinitiator followed by decarboxylation. The resulting alkyl radicals initiate the polymerization. Structures of the photoinitiators.

Optimization of Base-Catalyzed Transesterification Reaction of Used Cooking Oil

Abstract: Biodiesel is one of the environmentally friendly alternative liquid biofuels that has proven itself commercially, with international standards all around the world. Industrial and scientific studies on reducing biodiesel production costs are one of the major contributions that have strengthened the position of biodiesel commercially. The type of vegetable oil used for biodiesel production is the parameter that has the greatest effect on biodiesel production cost. For this reason, investigations on the types of no-to-low-cost vegetable oils become crucial. In this study, the optimum conditions for biodiesel production from restaurant-originated used cooking oil (which is composed primarily of oleic and linoleic acids) and the refining procedure were investigated. A refining method of “washing with hot water” was used for biodiesel refinement. One of the properties of biodiesel that has an influence on biodiesel purity is glycerin content. In the refining studies, the effects of glycerin amount, used washin...

Enhanced Orthogonal Frequency Division Multiplexing With Index Modulation

Abstract: Index modulation concept has attracted considerable research interest in the past few years As a realization of index modulation in the frequency domain, orthogonal frequency division multiplexing with index modulation (OFDM-IM) has recently been proposed, which conveys information bits through both the subcarrier activation patterns and the amplitude phase modulation constellation points This paper proposes two enhanced OFDM-IM schemes aimed at achieving higher spectral efficiency and diversity gain, respectively The first one, termed OFDM with hybrid in-phase/quadrature index modulation (OFDM-HIQ-IM), explores the I- and Q- dimensions jointly for index modulation, allowing transmission of more index modulation bits in each subcarrier group The second one, termed linear constellation precoded OFDM-IQ-IM (LP-OFDM-IQ-IM), spreads information symbols across two adjacent active subcarriers through linear constellation precoding to harvest additional diversity gain By maximizing the minimum squared Euclidean distance, two different realizations of LP-OFDM-IQ-IM are derived, which leads to a rotated and a diamond-shaped constellation, respectively The proposed OFDM-HIQ-IM and LP-OFDM-IQ-IM, as revealed by both theoretical analyses and computer simulations, enable low-complexity detection and exhibit superior error rate performance over the existing OFDM-IM schemes

A Review on the Effect of Drying on Antioxidant Potential of Fruits and Vegetables

Abstract: The role of antioxidants in human nutrition has gained increased interest, especially due to their associated health beneficial effects for a number of chronic diseases, including cardiovascular diseases and certain types of cancer. Fruits and vegetables are perishable and difficult to preserve as fresh products. Dried fruits and vegetables can be easily stored, transported at relatively low cost, have reduced packing costs, and their low water content delays microbial spoilage. Air-, freeze-, microwave- and sun-drying are among the most thoroughly studied drying methods. This review provides an overview of recent findings on the effects of different drying techniques on major antioxidants of fruits and vegetables. In particular, changes in ascorbic acid, carotenoids, flavonoids, phenolic acids, total phenolics, and antioxidant activity are discussed in detail.

Identification of trends in hydrological and climatic variables in Urmia Lake basin, Iran

Abstract: The drawdown trend of the water level in Urmia Lake poses a serious problem for northwestern Iran which has had negative impacts on agriculture and industry. This research investigated likely causes of the predicament by estimating trends in the time series of hydroclimatic variables of the basin. Three non-parametric statistical tests, the Mann–Kendall, Spearman rho, and Sen’s T, were applied to estimate the trends in the annual and seasonal time series of temperature, precipitation, and streamflow at 95 stations throughout the basin. The Theil–Sen method was also used to estimate the slopes of trend lines of annual time series. The results showed a significant increasing trend of temperature throughout the basin and an area-specific precipitation trend. The tests also confirmed a general decreasing trend in the basin streamflow that was more pronounced in the downstream stations. The annual trend line slope was found to be from 0.02 to 0.14 °C/year, −7.5 to 3.8 mm/year, and −0.01 to −0.4 m3/s/year for temperature, precipitation, and streamflow, respectively. The homogeneity of the monthly trends was also evaluated using the Van Belle and Hughes tests as confirmation. Temporal analyses of the trends for the temperature and streamflow of the basin detected significant increasing trends beginning in the mid-1980s and 1990s. The correlations between streamflow and climate variables (temperature and precipitation) were detected by Pearson’s test. The results showed that the streamflow in Urmia Lake basin is more sensitive to changes in temperature than precipitation. In general, the decline in the lake water level can be related to both the increase of temperature in the basin and an improvement in over-exploitation of the water resources.