A Holistic Investigation on Terahertz Propagation and Channel Modeling Toward Vertical Heterogeneous Networks

User-centric and low latency communications can be enabled not only by small cells but also through ubiquitous connectivity. Recently, the vertical heterogeneous network (V-HetNet) architecture is proposed to backhaul/fronthaul a large number of small cells. Like an orchestra, the V-HetNet is a polyphony of different communication ensembles, including geostationary orbit (GEO), and low-earth orbit (LEO) satellites (e.g., CubeSats), and networked flying platforms (NFPs) along with terrestrial communication links. In this study, we propose the Terahertz (THz) communications to enable the elements of V-HetNets to function in harmony. As THz links offer a large bandwidth, leading to ultra-high data rates, it is suitable for backhauling and fronthauling small cells. Furthermore, THz communications can support numerous applications from inter-satellite links to in-vivo nanonetworks. However, to savor this harmony, we need accurate channel models. In this paper, the insights obtained through our measurement campaigns are highlighted, to reveal the true potential of THz communications in V-HetNets.Comment: It has been accepted for the publication in IEEE Communications Magazin

Touristic Destinations’ Perceived Risk And Perceived Value As Indicators Of E-Wom And Revisit Intentions

In the process of destination selection, it is known that tourists perceive many different risks and use eWOM behavior as a risk reduction tool. Also the risks that consumers perceive are influential on the values they perceive. For this reason, spreading positive eWOM messages and encouraging revisit intentions are seen as significant competitive advantages in terms of destination management. In this context, to measure the effects of tourists’ perceived risk on their perceived value and the effects of their perceived value on their eWOM dissemination and revisit intentions, have been identified as the main objectives of this study. The sample of the study consists 228 tourists who visited the Fethiye (TR) destination in 2017. As a result of analysis of the data with Structural Equation Modeling, it is found that perceived risk variable has an impact on perceived value, perceived value variable has impacts on eWOM dissemination intention and revisit intention and eWOM dissemination intention has an impact on revisit intention

An investigation on renewable energy education at the university level in Turkey

In the present study, to discover how teaching of renewable energy sources in Turkey is carried out at the university level, a questionnaire was developed and applied at different universities in Turkey. The analyses conducted on the data obtained from the questionnaire revealed that education about geothermal, solar and wind energy is given at master’s level, other renewable energy sources are taught at the undergraduate level within the curriculum of some engineering courses. The teaching performed about renewable energy sources is in Turkish and at encyclopedic level. As preparing and obtaining the required materials are costly, some problems are encountered in the teaching of renewable sources. In Turkish universities, no degree about renewable energy sources is granted. Hence, the country must make use of the people having engineering degree to capitalize on its renewable energy sources. As there is no program specializing on providing training about the renewable energy sources, it seems to be difficult to find experts about this issue. The current state of renewable energy sources education seems to be inadequate and it should be expanded and strengthened

Modeling and Analysis of sub-Terahertz Communication Channel via Mixture of Gamma Distribution

With the recent developments on opening the terahertz (THz) spectrum for experimental purposes by the Federal Communications Commission, transceivers operating in the range of 0.1THz-10THz, which are known as THz bands, will enable ultra-high throughput wireless communications. However, actual implementation of the high-speed and high-reliability THz band communication systems should start with providing extensive knowledge in regards to the propagation channel characteristics. Considering the huge bandwidth and the rapid changes in the characteristics of THz wireless channels, ray tracing and one-shot statistical modeling are not adequate to define an accurate channel model. In this work, we propose Gamma mixture-based channel modeling for the THz band via the expectation-maximization (EM) algorithm. First, maximum likelihood estimation (MLE) is applied to characterize the Gamma mixture model parameters, and then EM algorithm is used to compute MLEs of the unknown parameters of the measurement data. The accuracy of the proposed model is investigated by using the Weighted relative mean difference (WMRD) error metrics, Kullback-Leibler (KL)-divergence, and Kolmogorov-Smirnov test to show the difference between the proposed model and the actual probability density functions (PDFs) that are obtained via the designed test environment. According to WMRD error metrics, KL-divergence, and KS test results, PDFs generated by the mixture of Gamma distributions fit the actual histogram of the measurement data. It is shown that instead of taking pseudo-average characteristics of sub-bands in the wideband, using the mixture models allows for determining channel parameters more precisely.Comment: This paper has been accepted for publication in IEEE Transactions on Vehicular Technolog

THEMIS: Time, Heterogeneity, and Energy Minded Scheduling for Fair Multi-Tenant Use in FPGAs

Using correct design metrics and understanding the limitations of the underlying technology is critical to developing effective scheduling algorithms. Unfortunately, existing scheduling techniques used \emph{incorrect} metrics and had \emph{unrealistic} assumptions for fair scheduling of multi-tenant FPGAs where each tenant is aimed to share approximately the same number of resources both spatially and temporally. This paper introduces an enhanced fair scheduling algorithm for multi-tenant FPGA use, addressing previous metric and assumption issues, with three specific improvements claimed First, our method ensures spatiotemporal fairness by considering both spatial and temporal aspects, addressing the limitation of prior work that assumed uniform task latency. Second, we incorporate energy considerations into fairness by adjusting scheduling intervals and accounting for energy overhead, thereby balancing energy efficiency with fairness. Third, we acknowledge overlooked aspects of FPGA multi-tenancy, including heterogeneous regions and the constraints on dynamically merging/splitting partially reconfigurable regions. We develop and evaluate our improved fair scheduling algorithm with these three enhancements. Inspired by the Greek goddess of law and personification of justice, we name our fair scheduling solution THEMIS: \underline{T}ime, \underline{H}eterogeneity, and \underline{E}nergy \underline{Mi}nded \underline{S}cheduling. We used the Xilinx Zedboard XC7Z020 to quantify our approach's savings. Compared to previous algorithms, our improved scheduling algorithm enhances fairness between 24.2--98.4\% and allows a trade-off between 55.3$\times$ in energy vs. 69.3$\times$ in fairness. The paper thus informs cloud providers about future scheduling optimizations for fairness with related challenges and opportunities

School Administrators' Resilience Level and Its Relation with Locus of Control

Bu araştırmada, Ankara İlindeki kamu ortaöğretim okulları yöneticilerinin yılmazlık düzeylerini belirlemek ve yılmazlık ile denetim odağı arasındaki ilişkiyi ortaya koymak amaçlanmıştır. Ayrıca denetim odağının yılmazlığı yordayıp yormadığı incelenmiştir. Veriler, bu okullarda görev yapan 290 yöneticiden toplanmıştır. Araştırma sonuçlarına göre yöneticilerin yılmazlık düzeyleri, cinsiyet, görev yapılan okul türü ve eğitim durumuna göre anlamlı bir farklılık göstermezken; kıdeme göre anlamlı olarak farklılaşmaktadır. Ayrıca yılmazlık ve denetim odağı arasında düşük seviyede ve negatif yönde anlamlı bir ilişkinin olduğu tespit edilmiştir. Denetim odağının boyutları olan iç kontrol inancı, kadercilik ve adil olmayan dünya inancının yılmazlığın anlamlı birer yordayıcısı olduğu belirlenmiştir.In this study, it was aimed to determine the administrators' resilience levels in public secondary schools in Ankara, and to reveal the relationship between resilience and locus of control. Moreover, it was investigated whether the locus of control predicted the resilience. The data were collected from 290 public secondary school administrators. According to the conclusions, there was no a significant difference in terms of gender, type of school, and education status variables; but there was a significant difference in terms of seniority in the resilience levels of the administrators. Besides, it was found there was a significant relationship between resilience and locus of control in a negative way and low level. It was determined that the dimesions of locus of control, which are belief of internal control, belief in fatalism and belief in an unfair world were all of a significant predictor of the resilience

Reconfigurable Intelligent Surfaces in Action for Non-Terrestrial Networks

Next-generation communication technology will be fueled on the cooperation of terrestrial networks with nonterrestrial networks (NTNs) that contain mega-constellations of high-altitude platform stations and low-Earth orbit satellites. On the other hand, humanity has embarked on a long road to establish new habitats on other planets. This deems the cooperation of NTNs with deep space networks (DSNs) necessary. In this regard, we propose the use of reconfigurable intelligent surfaces (RISs) to improve and escalate this collaboration owing to the fact that they perfectly match with the size, weight, and power restrictions of the operational environment of space. A comprehensive framework of RIS-assisted non-terrestrial and interplanetary communications is presented by pinpointing challenges, use cases, and open issues. Furthermore, the performance of RIS-assisted NTNs under environmental effects such as solar scintillation and satellite drag is discussed through simulation results.Comment: 7 pages, 6 figure

Seismic Assessment in a Historical Masonry Minaret by Linear and Non-linear Seismic Analyses

Operational Modal Analysis (OMA) method is frequently used in order to determine dynamical properties of historical masonry structures. In this study, damage pattern of historical Alaca minaret which is selected as application is investigated under different ground motions by updating finite element models (FEM) depending on operational modal analysis test. Initial Finite element model was prepared in ABAQUS V10 program and numerical dynamic characteristics of minaret were determined. In addition, experimental dynamic properties of minaret were provided by operational modal analysis. Initial numerical model of brick masonry structure was calibrated via OMA method. Then, linear and non-linear seismic analyses of calibrated FEM of historical minaret were performed by using different earthquakes acceleration records that occurred in Turkey. Concrete Damage Plasticity model was taken into account in non-linear seismic analyses. As a result of the analyses, it is concluded that the stresses obtained with linear analyses aren’t as realistic as the non-linear analyses results and the earthquakes can cause some damages in the minaret. &nbsp

Spectrum Sensing and Signal Identification with Deep Learning based on Spectral Correlation Function

Spectrum sensing is one of the means of utilizing the scarce source of wireless spectrum efficiently. In this paper, a convolutional neural network (CNN) model employing spectral correlation function which is an effective characterization of cyclostationarity property, is proposed for wireless spectrum sensing and signal identification. The proposed method classifies wireless signals without a priori information and it is implemented in two different settings entitled CASE1 and CASE2. In CASE1, signals are jointly sensed and classified. In CASE2, sensing and classification are conducted in a sequential manner. In contrary to the classical spectrum sensing techniques, the proposed CNN method does not require a statistical decision process and does not need to know the distinct features of signals beforehand. Implementation of the method on the measured overthe-air real-world signals in cellular bands indicates important performance gains when compared to the signal classifying deep learning networks available in the literature and against classical sensing methods. Even though the implementation herein is over cellular signals, the proposed approach can be extended to the detection and classification of any signal that exhibits cyclostationary features. Finally, the measurement-based dataset which is utilized to validate the method is shared for the purposes of reproduction of the results and further research and development

THE EFFECT OF THE CORONAVIRUS 19 OUTPUT ON LIFE SATISFACTION LEVELS IN UNIVERSITY STUDENTS

In this study, it was aimed to investigate the effect of the Coronavirus 19 epidemic on the life satisfaction levels of university students. The life satisfaction scale completed by a total of 530 university students was evaluated. Independent t-test, paired t-test, one-way analysis of variance, and LSD tests were used for statistical operations. Life satisfaction scores of university students did not show a statistically significant difference according to their gender, both before the epidemic and during the epidemic (p>0.05). Compared to the situation before the new Coronavirus 19 epidemic, life satisfaction scores during the epidemic decreased statistically significantly (p<0.001). During the epidemic, it was determined that life satisfaction scores changed according to sleep patterns and perception of forgiveness (p<0.05 and p<0.001). In this study, the difference in life satisfaction scores according to the level of exposure to coronavirus news in social media watching TV during the epidemic, and following coronavirus news on the internet is insignificant (p>0.05). Conclusion: It was concluded that the Coronavirus 19 epidemic did not show a significant difference according to gender on the life satisfaction levels of university students. However, life satisfaction levels were adversely affected during the new type of Coronavirus 19 epidemic. While sleeping patterns and reliance on their immunity were effective in this negative effect, it was seen that watching TV, following the news on the internet, and being exposed to news on social media about the epidemic were not effective. Necessary studies are recommended for university students to trust their immunity and to have good sleep patterns.  Article visualizations