A Survey of Air-to-Ground Propagation Channel Modeling for Unmanned Aerial Vehicles

In recent years, there has been a dramatic increase in the use of unmanned aerial vehicles (UAVs), particularly for small UAVs, due to their affordable prices, ease of availability, and ease of operability. Existing and future applications of UAVs include remote surveillance and monitoring, relief operations, package delivery, and communication backhaul infrastructure. Additionally, UAVs are envisioned as an important component of 5G wireless technology and beyond. The unique application scenarios for UAVs necessitate accurate air-to-ground (AG) propagation channel models for designing and evaluating UAV communication links for control/non-payload as well as payload data transmissions. These AG propagation models have not been investigated in detail when compared to terrestrial propagation models. In this paper, a comprehensive survey is provided on available AG channel measurement campaigns, large and small scale fading channel models, their limitations, and future research directions for UAV communication scenarios

Efficient numerical computation and experimental study of temporally long equilibrium scour development around abutment

YesFor the abutment bed scour to reach its equilibrium state, a long flow time is needed. Hence, the employment of usual strategy of simulating such scouring event using the 3D numerical model is very time consuming and less practical. In order to develop an applicable model to consider temporally long abutment scouring process, this study modifies the common approach of 2D shallow water equations (SWEs) model to account for the sediment transport and turbulence, and provides a realistic approach to simulate the long scouring process to reach the full scour equilibrium. Due to the high demand of the 2D SWEs numerical scheme performance to simulate the abutment bed scouring, a recently proposed surface gradient upwind method (SGUM) was also used to improve the simulation of the numerical source terms. The abutment scour experiments of this study were conducted using the facility of Hydraulics Laboratory at Nanyang Technological University, Singapore to compare with the presented 2D SGUM-SWEs model. Fifteen experiments were conducted over a total period of 3059.7 hours experimental time (over 4.2 months). The comparison shows that the 2D SGUM-SWEs model gives good representation to the experimental results with the practical advantage

Socially and biologically inspired computing for self-organizing communications networks

The design and development of future communications networks call for a careful examination of biological and social systems. New technological developments like self-driving cars, wireless sensor networks, drones swarm, Internet of Things, Big Data, and Blockchain are promoting an integration process that will bring together all those technologies in a large-scale heterogeneous network. Most of the challenges related to these new developments cannot be faced using traditional approaches, and require to explore novel paradigms for building computational mechanisms that allow us to deal with the emergent complexity of these new applications. In this article, we show that it is possible to use biologically and socially inspired computing for designing and implementing self-organizing communication systems. We argue that an abstract analysis of biological and social phenomena can be made to develop computational models that provide a suitable conceptual framework for building new networking technologies: biologically inspired computing for achieving efficient and scalable networking under uncertain environments; socially inspired computing for increasing the capacity of a system for solving problems through collective actions. We aim to enhance the state-of-the-art of these approaches and encourage other researchers to use these models in their future work

A novel model predictive-fuzzy logic hybrid controller design for D-STATCOM in wind energy distribution systems

WOS: 000428114800024Wind energy is a resource that does not require any fuel or feedstock to be treated, refined or transported. It does not produce air pollution and hazardous waste. Because of these, wind energy, one of the major renewable energy sources, has been widely used in recent years. In this work, a three-phase distribution static synchronous compensator (D-STATCOM) is demonstrated for power quality enhancement in wind energy distribution systems. A five-level cascaded inverter is used to implement the D-STATCOM. D-STATCOM is controlled to compensate the reactive power, balances the load and eliminate harmonics. A novel control algorithm is based on the indirect current control system with synchronous reference frame theory for generating the gating pulses of Voltage Source Inverter (VSI). This proposed control system has one model predictive controller and two modified fuzzy logic controllers. The performance of the three-phase D-STATCOM is validated for power quality enhancement with different loads through software implementation using Matlab/Simulink environment. The effectiveness of the proposed approach is verified through simulation studies.Turkey Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114E474]This work is supported by Turkey Scientific and Technological Research Council of Turkey (TUBITAK) with 114E474 numbered project, titled "Design and Implementation of a Smart STATCOM in Small Scale Wind Turbines"

Vegetable seed production in turkey

International Symposium on Agrotechnics and Storage of Vegetable and Ornamental Seeds/5th International Symposium on Seed Research in Horticulture -- JUN 14-16, 1993 -- BARI, ITALYWOS: A1994BD97V00001…Int Soc Hort Sci, Working Grp Seed Re

Kennismanagement bij wetenschappelijke onderzoeksinstituten; De rol van IT bij het creëren van 'corporate knowledge'

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Comparison of Levitation Forces of Bulk MgB2 Superconductors Produced by Nano Boron and Carbon-Doped Nano Boron

Celik, Sukru/0000-0002-6918-7569; DUZ, Ismahan/0000-0002-2298-232X; GUNER, SAIT BARIS/0000-0001-7487-4817; HOSSAIN, MD Shahriar/0000-0002-7291-9281; Ozturk, Kemal/0000-0002-8847-1880WOS: 000343162400010MgB2 bulk superconductors were prepared by hot press plus furnace heating method. Two types of boron powders were used, one is amorphous nano boron and the other is C-doped boron. Characteristics of superconductors were determined by XRD and resistance measurements. Systematic levitation force measurements were performed by using a modular system at low temperatures. These bulk superconductors showed around 9 N repulsive and 4 N attractive forces in the z-axis at 20 K at closest point to the cryostat lid which contains the MgB2 superconductor. These values slightly decreased by increasing temperature to 24 and 28 K for both samples. Comparing two samples, nano boron MgB2 showed slightly higher levitation force than C-doped MgB2 although C-doped MgB2 has higher attractive force value at the closest point. This situation points out that C-doped MgB2 is much proper for attractive force applications (as guidance force) while the nanoboron MgB2 sample is much appropriate for repulsive force (as levitation)

General status of cucurbit genetic resources in Turkey

9th EUCARPIA Meeting on Genetics and Breeding of Cucurbitaceae -- MAY 21-27, 2008 -- Avignon, FRANCEWOS: 000263558500001Turkey is very rich in cucurbit genetic resources due to its diverse geographical and ecological situation. Turkey is one of the important diversity centers for cultivated cucurbits because of the adaptation to diverse ecological conditions as result of natural selection and also the farmers selection in accordance with their preference. National collection of Citcurbitaceae species at National Gene Bank of Turkey (AARI) consists of 2223 accessions. Collecting activities have been systematically conducted since early 1960s. 25.7% of this amount is melon, 20.5% is Cucurbita spp., 16.1% is watermelon, 13.4% is cucumber, 7.7% is bottle gourd, 7.2% is squash, 4.2% is winter squash, 3.3% is snake melon, 1.3% is pumpkin, 0.3% Is other cucumbers, 0.2% squirting cucumber and 0.1% of bryony. Melon and watermelon genetic resources collections and their morphological and molecular characterization trials were done In Cukurova University and approximately 400 melon and 355 watermelon accessions were collected. Squash and pumpkin studies were done in Ondokuz Mayis and Ankara University and 128 winter squash, 40 pumpkin populations and 20 snack seed squash were collected and characterized. Selected pumpkins also were characterized molecularly. Bottle gourd characterization trials were done in Mustafa Kemal University and 188 accessions were characterized. Snake melon research activities were conducted at Ankara and Cukurova Universities and 62 accessions were characterized. The evaluation and breeding programs of these genetic resources are ongoing.EUCARPI