Trophic Characteristics of the Sapanca Lake (Turkey)

Systematic measurements of optical properties, concentrations of major and minor chemicals and primary production throughout 1989-1992 enabled us to identify the oligotrophic state of Sapanca lake, Marmara region, Turkey. Lake waters which have low concentrations of major anions and cations (total = 49 μM) overturn every February-March, ventilating the bottom waters and enriching the surface waters with nutrients. Surface waters cool down to 6.5 °C by late winter and then warm steadily to 26 °C by late summer, while temperatures in deep waters range between 6.5 and 10.0 °C throughout the year. When the seasonal thermocline develops, the dissolved oxygen profiles exhibit a subsurface maximum in the thermocline, while in the hypolimnion water, the content varies seasonally from 11.5-12.0 ppm (350-375 μM) in March to 0.5-1.7 ppm (16-56 μM) in late autumn. Surface nitrate concentrations vary markedly with season, from < 0.15 μM in summer to 5.7 μM in early March, whilst the bottom water concentrations range from 13.5-14.0 μM in late autumn to 5.7 μM after the winter overturn. Phosphate concentrations are always less than 0.1 μM throughout the entire water column. Subsurface chlorophyll-a maximum descends in late summer to 20-25 m depths, where the light intensity is less than 1% of the surface value. Below 10-15 m depths, corresponding to the upper thermocline, primary productivity is very low. The range was from 35 to 93 mg C/ m2 day-1 during 1989-1991, consistent with the values in other oligotrophic lakes

Detection of gamma responses in EEG signals [EEG sinyallerinde gamma tepkisinin tespiti]

In the detection of the existence of the early gamma response, subjective methods have been used. In this study, an automated gamma detection technique is developed based on the features obtained from the time - frequency representation of the EEG signal in the gamma frequency band. The technique easily discriminates the gamma response existing and non-existing cases for the generated synthetic data. The classification of the technique and that of the expert opinion coincide %77 for real EEG data. © 2006 IEEE

A heuristic procedure for a single-item dynamic lot sizing problem

An O(T) heuristic proceudre for a single-item dynamic lot sizing problem is introduced in this paper. The algorithm tries to establish the regeneration points of the problem whether either the production or the beginning inventory must be equal to zero. The proposed algorithm is very easy to implement and compares very favourably with the existing heuristic procedures.Publisher's Versio

An investigation on decrease in the efficiency of IMAC HP-IIIE type resins

In this study, the efficiency of the resins, whose commercial name is IMAC HP-IIIE type strong acidic cationic resins, for removing hardness from water is investigated. For this purpose, water with hardness of 62, French unit was passed through 100 mi of the resin in a column at a rate of 80 ml/minute to obtain the breakthrough curve. This process was repeated two times after regenerating the resins at the end of the each run. Later, the experiment was continued in the same way using waters with 84 and 108 French hardness, respectively

A computational and experimental study on a harsh environment LED system for vehicle exterior lighting applications

Due to copyright restrictions, the access to the full text of this article is only available via subscription.Effect of compact thermal packaging approaches and challenges are investigated for a next generation automotive LED lighting. A challenging three-purpose in one (3i1) highly packaged light emitting diodes (LEDs) lighting system has been studied computationally and experimentally. A tightly packed light engine printed circuit board (PCB) with both LEDs and electronics in a very hermetically sealed enclosure close to the vehicle engine department pose significant thermal and mechanical challenges for the thermal design as well as optical considerations. Challenge is due to local high ambient temperatures and aggressive operating conditions. Finite element based computational models have been developed first to study a single package thermal performance, and then followed by system level computational fluid dynamics (CFD) models. Later, a series of experiments and analytical studies have been performed for validation of computational results. It is found that interface layer at the package poses significant bottlenecks for meeting the design requirements. System level CFD models showed that having a two-sided flame retardant (FR4) based board causes local hot spots that need innovative system level cooling solutions.Turkish Ministry of Science ; Industry and Technology SANTEZ ; FARBA AŞ