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Yayın Positive solutions for a sum-type singular fractional integro-differential equation with m-point boundary conditions(Politechnica University of Bucharest, 2017) Aydoğan, Seher Melike; Nazemi, Sayyedeh Zahra; Rezapour, ShahramWe study the existence and uniqueness of positive solutions for a sum-type singular fractional integro-differential equation with m-point boundary condition. Also, we provide an example to illustrate our main result.Yayın Maximum likelihood blind channel estimation for space-time coding systems(Hindawi Publishing Corporation, 2002-05) Çırpan, Hakan Ali; Panayırcı, Erdal; Çekli, ErdinçSophisticated signal processing techniques have to be developed for capacity enhancement of future wireless communication systems, In recent years, space-time coding is proposed to provide significant capacity gains over the traditional communication systems in fading wireless channels. Space-time codes are obtained by combining channel coding, modulation, transmit diversity, and optional receive diversity in order to provide diversity at the receiver and coding gain without sacrificing the bandwidth. In this paper, we consider the problem of blind estimation of space-time coded signals along with the channel parameters. Both conditional and unconditional maximum likelihood approaches are developed and iterative solutions are proposed. The conditional maximum likelihood algorithm is based on iterative least squares with projection whereas the unconditional maximum likelihood approach is developed by means of finite state Markov process modelling. The performance analysis issues of the proposed methods are studied. Finally, some simulation results are presented.Yayın Using the ultrasonic stress wave technique to evaluate structural timber members of an old masonry building(Kastamonu Univ, Orman Fak, 2018) Koca, Gülru; Dündar, Türker; As, NusretAim of study: The main objective of this study is to evaluate the current state of the structural timber members of an old masonry building by using destructive and non-destructive test methods and to determine the efficiency of non-destructive test methods by obtaining correlations between destructive and non-destructive test parameters. Area of study: Specimens were extracted from different parts of an old semi-detached masonry building in Istanbul, Turkey. The building was built at the beginning of the 20th century in Kadikoy, a residential district in the Asia side of Istanbul. Material and Methods: Ultrasonic stress wave test was carried out on specimens prepared from the structural members. Following the ultrasonic based non-destructive tests, the bending strength and modulus of elasticity in the bending tests were determined for the specimens. Main results: According to the results of the experiments, it was observed that the regression correlations were high for the softwoods (fir and spruce), but relatively lower correlations were obtained for the chestnut specimens. Highlights: Because of the good R-2 values obtained between the MOED and mechanical properties of the softwoods, the non-destructive stress wave technique can be recommended for the evaluation of softwoods in structures. Although chestnut showed very good mechanical properties, a satisfactory evaluation of the chestnut members could not be obtained because of the small number of specimens. Further investigation is needed with large sample groups.Yayın RETRACTED: Efficiency analysis of the dynamic traffic control for an urban highway (Retracted article. See 185, 2016)(Springer International Publishing AG, 2015-03-07) Kesten, Ali Sercan; Ergün, MuratIn this study, dynamic traffic control strategies, namely dynamic ramp metering and dynamic speed limit control, have been examined through microscopic traffic simulation based on site measurements. In this context, the traffic flow data at a particular highway intersection have been analyzed to determine the pattern of the traffic. Then, the traffic model has been built in a traffic micro-simulation software and calibrated with the field data. The foci of the study are to measure the efficiency of the dynamic traffic control strategies and to compare it with the uncontrolled case considering various performance indicators such as total travel time, average delay time per vehicle, and average number of stops per vehicle. For the dynamic ramp metering strategies, the ALINEA (Asservissement Lineaire d'Entree Autoroutiere - French for Linear Utilization for Highway Entrances) control algorithm is implemented with different fixed-time cycle lengths. It has been observed that various ramp metering implementations decreased the average delay time per vehicle up to 30%. The dynamic speed limit control strategies are set according to the occupancy rates that are measured at the bottleneck downstream. The examined speed limit control strategies decreased the average delay time per vehicle to around 7%. The results also revealed that the implemented dynamic traffic control strategies help alleviate congestion by increasing the capacity of the bottleneck section.Yayın Space, time, and iconicity in Turkish sign language (TID)(Estonian Academy Publishers, 2012) Arik, EnginMuch evidence points to the conclusion that temporal concepts are drawn primarily from the conceptualization of space. Sign languages provide a particularly suitable area for observing such a relationship since they employ a three-dimensional signing space as a major building block for articulation. This paper addresses spatial and temporal language in Turkish Sign Language (TID), which has a full-fledged grammar and a natural language used by the deaf community in Turkey. It investigates descriptions of static and dynamic spatial situations and expressions of time. Results showed mismatches between the axial information in the stimuli and the use of left-right and front-back axes in the signing space. Furthermore, results also showed that the temporal language did not always correlate with the deictic use of the front-back axis. Thus, these findings suggest that temporal language may only partially be derived from spatial language.Yayın Projected future changes in extreme climate indices over Central Asia using RegCM4.3.5(MDPI, 2023-06) Öztürk, TuğbaThis work projected future extreme climate indices' changes over Central Asia (The Coordinated Regional Climate Downscaling Experiment-CORDEX Region 8). Changes were calculated for 2071-2100 relative to 1971-2000. Climate simulations were obtained by downscaling the RegCM4.3.5 to 50 km resolution under RCP4.5 and 8.5 with HadGEM2-ES and MPI-ESM-MR. The results indicate that the Central Asian domain will experience warmer and more extreme temperatures with increasing radiative forcing. The annual lowest value of minimum daily temperature was simulated to increase remarkably, up to 8 degrees, especially in high latitudes, with a more than 12 degree increase projected over Siberia. A strong growth in the percentage of warm nights and an increase in the days of warm spells for the whole region, with a decrease in cold spell duration, are anticipated. Model results show an expected reduction of up to 30% in precipitation totals over the domain, except for the increased precipitation over Siberia, the Himalayas, and Tibetan Plateau. Extreme precipitation events are projected to have an increase of 20% over the whole domain, with an 80% increase over high topographical areas.Yayın A novel image compression method based on classified energy and pattern building blocks(Springer International Publishing AG, 2011) Güz, ÜmitIn this paper, a novel image compression method based on generation of the so-called classified energy and pattern blocks (CEPB) is introduced and evaluation results are presented. The CEPB is constructed using the training images and then located at both the transmitter and receiver sides of the communication system. Then the energy and pattern blocks of input images to be reconstructed are determined by the same way in the construction of the CEPB. This process is also associated with a matching procedure to determine the index numbers of the classified energy and pattern blocks in the CEPB which best represents (matches) the energy and pattern blocks of the input images. Encoding parameters are block scaling coefficient and index numbers of energy and pattern blocks determined for each block of the input images. These parameters are sent from the transmitter part to the receiver part and the classified energy and pattern blocks associated with the index numbers are pulled from the CEPB. Then the input image is reconstructed block by block in the receiver part using a mathematical model that is proposed. Evaluation results show that the method provides considerable image compression ratios and image quality even at low bit rates.Yayın Timelike rotational surfaces of elliptic, hyperbolic and parabolic types in minkowski space E-1(4) with pointwise 1-type gauss map(University of Nis, 2015) Bektaş, Burcu; Dursun, UğurIn this work, we focus on a class of timelike rotational surfaces in Minkowski space E-1(4) with 2-dimensional axis. There are three types of rotational surfaces with 2-dimensional axis, called rotational surfaces of elliptic, hyperbolic or parabolic type. We obtain all flat timelike rotational surface of elliptic and hyperbolic types with pointwise 1-type Gauss map of the first and second kind. We also prove that there exists no flat timelike rotational surface of parabolic type in E-1(4) with pointwise 1-type Gauss map.Yayın Modelling and simulation studies on adaptive controller for alt-azimuth telescopes despite unknown wind disturbance and mass(SAGE Publications, 2020-09-15) Keskin, Onur; Ünal, Ali Cem; Kararsız, Gökhan; Yılmaz, Tuğrul; Yeşilyaprak, CahitNumerous ground-based observatories are using small sized ground telescopes for scientific research purposes. The telescopes that are available on the market have three main problems. These issues can be listed as: positioning repeatability, tuning requirement according to different wind speeds for different seasons, and the mass changing via different scientific equipments added to the telescope. This study is aimed at resolving these issues for ground based small alt-azimuth telescopes. Establishing of a set and forget system is performed by designing an adaptive controller. Motor dynamics are taken into consideration for a realistic mathematical model. The Wind-Gust model that consists of a sum of sinusoidal disturbances with unknown phase, amplitude and frequency is used for the wind model. The purposed controller cancels the disturbance effects on the plant while operational positioning and also the makes the plant insensitive to mass changes. The Lyapunov approach is utilised when proving the asymptotic stability. The proposed controller’s success is illustrated with thorough numerical evaluation.Yayın Projected changes in extreme temperature and precipitation indices over CORDEX-MENA domain(MDPI AG, 2021-05) Öztürk, Tuğba; Saygılı Aracı, Fatma Sibel; Kurnaz, Mehmet LeventIn this study, projected changes in climate extreme indices defined by the Expert Team on Climate Change Detection and Indices were investigated over Middle East and North Africa. Changes in the daily maximum and minimum temperature-and precipitation-based extreme indices were analyzed for the end of the 21st century compared to the reference period 1971–2000 using regional climate model simulations. Regional climate model, RegCM4.4 was used to downscale two different global climate model outputs to 50 km resolution under RCP4.5 and RCP8.5 scenarios. Results generally indicate an intensification of temperature-and precipitation-based extreme indices with increasing radiative forcing. In particular, an increase in annual minimum of daily minimum temperatures is more pronounced over the northern part of Mediterranean Basin and tropics. High increase in warm nights and warm spell duration all over the region with a pronounced increase in tropics are projected for the period of 2071–2100 together with decrease or no change in cold extremes. According to the results, a decrease in total wet-day precipitation and increase in dry spells are expected for the end of the century.
