OpenAIRE Collection / OpenAIRE Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/11147/17

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Citation - WoS: 6
Citation - Scopus: 9
Adaptive Limited Feedback Links for Cooperative Multi-Antenna Multicell Networks
(Springer Verlag, 2014) Özbek, Berna; Ruyet, Didier Le
The overall performance of cooperative networks is quite sensitive to channel state information (CSI) of serving and interfering base stations (BSs) and affected strongly by quality of limited feedback links. In this paper, we propose two adaptive limited feedback strategies for intercell interference cancelation in multi-antenna multicell networks. The first proposed strategy is developed to improve average multicell capacity assuming a fixed rate feedback link. This algorithm is based on adaptation of the number of bits to quantize CSI of serving and interfering BSs according to transmitter power and location of the user in its own cell. The second proposed strategy is designed in a way to increase average capacity of cell-edge users assuming an adaptive rate feedback link. This algorithm is based on the idea of allocating more bits to quantize CSI of users at cell-edge regions while allocating less bits for users near the serving BS. We illustrate performance of the proposed feedback links for downlink cooperative multi-antenna multicell networks in wireless channels.
Citation - WoS: 4
Citation - Scopus: 4
Analytical Solution of Micro-/Nanoscale Convective Liquid Flows in Tubes and Slits
(Springer, 2017) Kalyoncu, Gülce; Barışık, Murat
Analytical solutions examining heat transport in micro-/nanoscale liquid flows were developed. Using the energy equation coupled with fully developed velocity, we solved developing temperature profiles with axial conduction and viscous dissipation terms. A comprehensive literature review provided the published range of velocity slip and temperature jump conditions. While molecular simulations and experiments present constant slip and jump values for a specific liquid/surface couple independent of confinement size, non-dimensional forms of these boundary conditions were found appropriate to calculate non-equilibrium as a function of flow height. Although slip and jump conditions are specific for each liquid/surface couple and hard to obtain, we proposed modeling of the slip and jump as a function of the surface wetting, in order to create a general, easy to measure methodology. We further developed possible correlations to calculate jump using the slip value of the corresponding surface and tested in the results. Fully developed Nu showed strong dependence on slip and jump. Heat transfer stopped when slip and jump coefficients became higher than a certain value. Strong variation of Nu in the thermal development length was observed for low slip and jump cases, while an almost constant Nu in the flow direction was found for high slip and jump coefficients. Variation of temperature profiles was found to dominate the heat transfer through the constant temperature surface while surface and liquid temperatures became equal at heat transfer lengths comparable with confinement sizes for no-dissipation cases. In case of non-negligible heat dissipation, viscous heating dominated the Nu value by enhancing the heating while decreasing the heat removal in cooling cases. Implementation of proposed procedure on a micro-channel convection problem from a micro-fluidics application showed the dominant effect of the model defining the slip and jump relationship. Direct use of kinetic gas theory resulted in an increase of Nu by an increase in non-equilibrium, while models developed from published liquid slip and jump values produced an opposite behavior.
Citation - WoS: 2
Citation - Scopus: 1
Ankos Publisher Application System and Its Impact on the E-Resource Evaluation Process
(Taylor and Francis Ltd., 2013-02-20) Bulut, Burcu; Uğur, Handan; Gürdal, Gültekin; Holt, İlkay; Çukadar, Sami; Akbayrak, Emre H.; Çelebi, Mustafa K.
The Publisher Application System(PAS) is aWeb-based archiving and online evaluation systemdeveloped by the Database Evaluation Group (DEG), one of the working groups formed within the Anatolian University Libraries Consortium (ANKOS). The DEG was formed in 2008 to inquire and evaluate e-resources suited to the needs of the consortium; to follow up similar consortial activities worldwide as well as developments in connection with the scientific publishing industry; and to determine, implement, and improve pricing models in accordance with the prevailing economic, legal, and academic system. Development of the PAS was essential to ensure standardization and sustainability towards a more detailed and effective analysis of e-resources qualifying for evaluation by ANKOS. The PAS played an important part not only in establishing and defining the workflow of the DEG, but also in creating an archive of both the e-resources submitted to the consortium and the applicant publishers/agents submitting these resources. This article outlines the process that started with the foundation of the DEG through the formation of the PAS as well as the present setup of the system. It is also hoped that this case study will have a positive contribution to the processes being followed by the persons and the groups engaged in similar activities.

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