10 sonuçlar
Arama Sonuçları
Listeleniyor 1 - 10 / 10
Yayın Energy and data cooperation in energy harvesting multiple access channel(IEEE, 2016) Gürakan, Berk; Şişman, Berrak; Kaya, Onur; Ulukuş, SennurWe consider the energy harvesting two user Gaussian multiple access channel (MAC), where both users harvest energy from nature. The users cooperate at the physical layer (data cooperation) by establishing common messages through overheard signals and then cooperatively sending them. In addition, the users cooperate at the battery level (energy cooperation) by wirelessly transferring energy to each other. We find the jointly optimal offline transmit power and rate allocation policy together with the energy transfer policy that maximizes the departure region. We provide necessary conditions for energy transfer, and prove some properties of the optimal transmit policy, thereby shedding some light on the interplay between energy and data cooperation.Yayın Benefiting innovative capabilities of software developer/user communities in developing countries(IEEE, 2010) Ansal, Hacer; Yıldırım, NihanSince technological innovation is generally considered to be a major force in global economic growth, the development of innovative capabilities in developing countries has been a very important policy issue. Free/Libre Open Source Software (FLOSS) has reshaped software technology through the creation of developer/user communities which enabled the collaboration of different parties resulting in the production of Linux and similar software projects. FLOSS user/developer community networks serve not only as "learning, reviewing, and testing" environments for developers, but they may also act as innovation networks that contribute to the improvement of the innovative capabilities of individual developers within the community. Therefore, understanding the characteristics, the motivating factors and the innovative dynamics of these developer communities will provide valuable insight into how to improve the innovative capabilities of developing countries in relation to software.The aim of this paper is to explore the characteristics of FLOSS developer communities in order to discover what benefits they may offer developing countries in generating innovative capabilities related to software. By conducting a survey in the FLOSS user/developer community in Turkey, the demographic characteristics, motivation factors and innovative characteristics of the community are explored and the question of whether these communities may act as innovation networks is examined. It is concluded that FLOSS community networks mostly serve as knowledge sharing and collaboration platforms, however, they do have the potential to evolve into innovation networks if they receive support from the local software industry and academic institutions.Yayın Circuit model for given reflectance data constructed with mixed lumped and distributed elements for high speed/high frequency communication systems(IEEE, 2005) Yarman, Bekir Sıddık Binboğa; Şengül, Metin; Kılınç, Ali; Aksen, AhmetIn this paper, a reflectance-based "non linear interpolation method" is presented to model the measured or computed data, obtained from a "passive one-port physical device" using mixed lumped and distributed elements. Mixed element model is constructed with cascade connection of series inductors [L], commensurate transmission lines or so called Unit Elements [UE] and shunt capacitors[C]. Basis of the new model rests on the numerical generation of the scattering parameters of the lossless two-port constructed with cascade connection of simple [L]-[UE]-[C] elements which describes a lossless 2-port in Darlington sense. The new modeling technique does not require direct optimization of the circuit elements of the selected topology. Rather, two-variable reflection coefficient is directly determined by means of a non linear but "convergence guaranteed" interpolation process to best fit the given data. A low-pass filter input reflection coefficient modeling example is included to exhibit the utilization of the proposed modeling method.Yayın Force-directed approaches to sensor localization(SIAM, 2006) Efrat, Alon; Forrester, David; Iyer, Anand; Kobourov, Stephen G.; Erten, CesimWe consider the centralized, anchor-free sensor localization problem. We consider the case where the sensor network reports range information and the case where in addition to the range, we also have angular information about the relative order of each sensor's neighbors. We experimented with classic and new force-directed techniques. The classic techniques work well for small networks with nodes distributed in simple regions. However, these techniques do not scale well with network size and yield poor results with noisy data. We describe a new force-directed technique, based on a multi-scale dead-reckoning, that scales well for large networks, is resilient under range errors, and can reconstruct complex underlying regions.Yayın Channel adaptive encoding and decoding strategies and rate regions for the three user cooperative multiple access channel(IEEE, 2008) Edemen, Çağatay; Kaya, OnurFor a cooperative Gaussian multiple access channel (MAC), we propose a new channel adaptive three user cooperation strategy, based on a non-trivial extension of block Markov super-position encoding. We obtain the expressions for the resulting achievable rate region. We demonstrate through simulations that the participation of an extra user in cooperation provides significant rate improvements. The proposed strategy also improves upon our earlier results on the three user cooperative MAC [1], under certain channel conditions.Yayın Achievable rates for the three user cooperative multiple access channel(IEEE, 2008) Edemen, Çağatay; Kaya, OnurFor a three user Gaussian multiple access channel (MAC), we propose a new superposition block Markov encoding based cooperation scheme. Our scheme allows the three users to simultaneously cooperate both in pairs, and collectively, by dividing the transmitted messages into sub messages intended for each cooperating partner. The proposed encoding and decoding at the transmitters take into account the relative qualities of the cooperation links between the transmitters. We obtain and evaluate the achievable rate region based on our encoding strategy, and compare it with the achievable rates for the two user cooperative MAC. We demonstrate that the added diversity by the presence of the third user improves the region of achievable rates, and this improvement is especially significant as far as the sum rate of the system is concerned.Yayın Constructing a Turkish constituency parse treeBank(Springer Verlag, 2016) Yıldız, Olcay Taner; Solak, Ercan; Çandır, Şemsinur; Ehsani, Razieh; Görgün, OnurIn this paper, we describe our initial efforts for creating a Turkish constituency parse treebank by utilizing the English Penn Treebank. We employ a semiautomated approach for annotation. In our previouswork [18], the English parse trees were manually translated to Turkish. In this paper, the words are semi-automatically annotated morphologically. As a second step, a rule-based approach is used for refining the parse trees based on the morphological analyses of the words. We generated Turkish phrase structure trees for 5143 sentences from Penn Treebank that contain fewer than 15 tokens. The annotated corpus can be used in statistical natural language processing studies for developing tools such as constituency parsers and statistical machine translation systems for Turkish.Yayın A frequency transformation based real frequency design approach for dual-band matching(IEEE, 2017) Aksen, Ahmet; Yıldız, Serkan; Yarman, Bekir Sıddık BinboğaThis work describes a real frequency design approach for dual-band matching networks. The proposed design technique employs a direct low-pass to dual pass band frequency transformation in the scattering based real frequency design of transformer free double band matching filters. For prescribed matching pass-bands, the parameters of dual-band frequency transformation are also iterated to enhance the matching band control in the nonlinear optimization process. A dual band matching network design example is presented to illustrate the application of the design approach.Yayın A new block Markov coding strategy for pairwise and collective cooperation in the three user MAC(IEEE, 2013) Edemen, Çağatay; Kaya, OnurFor a three user cooperative multiple access channel (MAC), we propose a new block Markov superposition encoding strategy, which enables all three users to cooperate collectively as well as in pairs. We obtain the resulting achievable rate expressions and compare them with existing two and three user cooperative strategies. We demonstrate that significant rate gains may be possible, without resorting to adaptive encoding/decoding techniques. We investigate the contributions from pairwise and collective cooperation signals while achieving tuples on the rate region boundary, and compare by simulations the sum rates achievable by two user versus three user grouping in cooperative MACs with fixed total resources.Yayın Reflectance data model with mixed lumped and distributed elements for wireless communication systems(IEEE, 2005) Yarman, Bekir Sıddık Binboğa; Şengül, Metin; Kılınç, Ali; Aksen, AhmetIn this paper, a new method is presented to model the given reflectance data obtained from a "passive one-port physical device", as a lossless two port consists of lumped and distributed elements. Basis of the new method rests on the interpolation of the given data as a realizable bounded-real (BR) reflection function in two variables. The desired circuit model is then obtained as the result of the synthesis of this function in two kinds of elements; namely, distributed and lumped circuit elements. An algorithm is presented to generate the circuit model step by step and an example is also included to exhibit the utilization of the new modeling algorithm.
