Vah, Yahya Kemal, vah!

Taha Toros Arşivi, Dosya No: 182-Yahya Kemal Beyatlı. Not: Gazetenin "Dile Gelen İstanbul" köşesinde yayımlanmıştır.İstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

Cumhuriyetle yaşıt bir öykücü:Oktay Akbal

Taha Toros Arşivi, Dosya No: 130-Oktay AkbalUnutma İstanbul projesi İstanbul Kalkınma Ajansı'nın 2016 yılı "Yenilikçi ve Yaratıcı İstanbul Mali Destek Programı" kapsamında desteklenmiştir. Proje No: TR10/16/YNY/010

On the classification of binary space shift keying modulation

Blind and non-cooperative classification of the modulation employed in signals originating from unknown or partly known sources has widespread applications in civilian and military contexts. One of the most recent and interesting approaches to digital modulation which has been enabled by multiantenna transceivers is the spatial modulation, where the indices of the transmit antennas activated in a given symbol period are utilized to transmit information bits. Clearly, existing modulation classification methods, designed for the identification of conventional modulation types, are not capable of classifying the family of spatially modulated signals that make use of the space dimension. In this work, for the first time in the literature, a modulation classification method is proposed for a modulation type belonging to the family of Spatial Modulations: the Binary Space Shift Keying modulation (BSSK

Retail productivity in space: Capturing productivity returns to market potential in the Swedish retail sector

This paper investigates the impact of market accessibility on productivity, where market potential is calculated in terms of the time-distances between market places of different aggregation levels, and wage sums in the respective markets. In particular, the empirical analysis explores the productivity in retail sector where overall economy is used as a benchmark. Analysis is conducted for central and peripheral market places separately to see whether there is a notable variation implying an urban-periphery structure when it comes to the impact of market size on productivity in the Swedish economy. Retail sector is in the focus of the study because it is constituted by economic activities that are highly dependent on proximity to demand and density in the market place. Consequently, following the theoretical foundation on productivity returns to scale and density, one can expect an higher impact in the retail sector compared to the rest of the economy. Based on this proposition, this paper provides an empirical investigation where individual earnings in the entire economy are investigated first on establishment level and on individual level. Several characteristics of establishments, the economic milieu and individuals are taken into consideration in the empirical design. This paper contributes to the existing literature by introducing an overall retail productivity analysis where the entire economy is in question. Instead of examining retail trade in terms of geographically aggregate measures, and sector specific output measures that are not easy to compare across industries, paper treats individual earnings as a proxy for productivity which enables for an in-depth comparative analysis

Receding contact problem for two elastic layers resting on a Winkler foundation

In this study, receding contact problem for two elastic layers resting on a Winkler foundation and loaded by means of a rigid circular punch is considered. The elastic layers have different heights and elastic constants. External load is applied to the upper elastic layer by means of a rigid circular punch and the lower elastic layer rests on a Winkler foundation. The problem is solved under the assumptions that the contact between elastic layers, and between the rigid punch and the upper elastic layer are frictionless and the effect of gravity forces is neglected. Since the contact between two bodies is assumed to be frictionless, then only compressive normal tractions can be transmitted in the contact areas. General equations of stresses and displacements which are required for the solution of the problem are obtained by using the theory of elasticity and the integral transform techniques. Using integral transform technique and boundary conditions of the problem, the problem is reduced to a system of singular integral equations in which the contact stresses and areas are the unknown functions. The system of singular integral equations is solved numerically by making use of appropriate Gauss-Chebyshev integration formulas and an iterative scheme is employed to obtain the correct contact half-areas that satisfies the equilibrium conditions. Numerical results for the contact stresses and the contact areas are given for various dimensionless quantities

Winkler Zemine Oturan Elastik İki Tabaka İçin Sürekli Temas Probleminin Sonlu Elemanlar Yöntemi Kullanılarak Çözümü

Konferans Bildirisi -- Teorik ve Uygulamalı Mekanik Türk Milli Komitesi, 2015Conference Paper -- Theoretical and Applied Mechanical Turkish National Committee, 2015Bu çalışmada, düzgün yayılı yük ile yüklenmiş ve Winkler zemine oturan birbirine yapışık elastik iki tabakanın sürekli temas problemi sonlu elemanlar yöntemi kullanılarak çözülmüştür. Çözümde tabakaların kütle kuvvetleri ihmal edilmiştir. Problem düzlem hal için incelendiğinden z ekseni doğrultusundaki kalınlık birim olarak alınmıştır. Problemin sonlu eleman modeli ANSYS paket programı kullanılarak oluşturulmuş ve iki boyutlu analizi yapılmıştır. En büyük normal gerilmeler simetri ekseni üzerinde meydana geldiğinden, bu eksende oluşan sx ve sy gerilmeleri çeşitli boyutsuz büyüklükler için elde edilmiştir. Son olarak bulunan sonuçlar literatürdeki analitik sonuçlarla karşılaştırılarak doğrulanmıştır.In this paper, a continuous contact problem for two bonded elastic layers resting on a Winkler foundation and loaded by uniformly distributed load is solved using finite element method. Body forces of elastic layers are neglected in the problem. Thickness in z-direction is taken to be unit. The finite element model of the problem is constituted using ANSYS software and the two dimensional analysis of the problem is carried out. By reason of the fact that maximum value of the normal stress is on the symmetry axis, sx and sy stresses on the symmetry axis are determined for various dimensionless quantities. Finally, the results obtained from finite element method are verified by comparison with the analytical results

TRT, terör ve Ermeni sorunu üzerine belgeler, bilgiler

Taha Toros Arşivi, Dosya No: 77/A-Ermenilerİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

Robust position control of a tilt-wing quadrotor

This paper presents a robust position controller for a tilt-wing quadrotor to track desired trajectories under external wind and aerodynamic disturbances. Wind effects are modeled using Dryden model and are included in the dynamic model of the vehicle. Robust position control is achieved by introducing a disturbance observer which estimates the total disturbance acting on the system. In the design of the disturbance observer, the nonlinear terms which appear in the dynamics of the aerial vehicle are also treated as disturbances and included in the total disturbance. Utilization of the disturbance observer implies a linear model with nominal parameters. Since the resulting dynamics are linear, only PID type simple controllers are designed for position and attitude control. Simulations and experimental results show that the performance of the observer based position control system is quite satisfactory

Robust hovering control of a quad tilt-wing UAV

This paper presents design of a robust hovering controller for a quad tilt-wing UAV to hover at a desired position under external wind and aerodynamic disturbances. Wind and the aerodynamic disturbances are modeled using the Dryden model. In order to increase the robustness of the system, a disturbance observer is utilized to estimate the unknown disturbances acting on the system. Nonlinear terms which appear in the dynamics of the vehicle are also treated as disturbances and included in the total disturbance. Proper compensation of disturbances implies a linear model with nominal parameters. Thus, for robust hovering control, only PID type simple controllers have been employed and their performances have been found very satisfactory. Proposed hovering controller has been verified with several simulations and experiments

LQR and SMC stabilization of a new unmanned aerial vehicle

We present our ongoing work on the development of a new quadrotor aerial vehicle which has a tilt-wing mechanism. The vehicle is capable of take-off/landing in vertical flight mode (VTOL) and flying over long distances in horizontal flight mode. Full dynamic model of the vehicle is derived using Newton-Euler formulation. Linear and nonlinear controllers for the stabilization of attitude of the vehicle and control of its altitude have been designed and implemented via simulations. In particular, an LQR controller has been shown to be quite effective in the vertical flight mode for all possible yaw angles. A sliding mode controller (SMC) with recursive nature has also been proposed to stabilize the vehicle’s attitude and altitude. Simulation results show that proposed controllers provide satisfactory performance in achieving desired maneuvers