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Conference Object Statistical Randomness Tests of Long Sequences by Dynamic Partitioning(Ieee, 2020) Akcengiz, Ziya; Asian, Melis; Karabayir, Ozgur; Doganaksoy, Ali; Uguz, Muhiddin; Sulak, FatihRandom numbers have a wide usage in the area of cryptography. In practice, pseudo random number generators are used in place of true random number generators, as regeneration of them may be required. Therefore because of generation methods of pseudo random number sequences, statistical randomness tests have a vital importance. In this paper, a randomness test suite is specified for long binary sequences. In literature, there are many randomness tests and test suites. However, in most of them, to apply randomness test, long sequences are partitioned into a certain fixed length and the collection of short sequences obtained is evaluated instead. In this paper, instead of partitioning a long sequence into lixed length subsequences, a concept of dynamic partitioning is introduced in accordance with the random variable in consideration. Then statistical methods are applied. The suggested suite, containing four statistical tests: Collision Tests, Weight Test, Linear Complexity Test and Index Coincidence Test, all of them work with the idea of dynamic partitioning. Besides the adaptation of this approach to randomness tests, the index coincidence test is another contribution of this work. The distribution function and the application of all tests are given in the paper.Conference Object Citation - WoS: 2Citation - Scopus: 3Design Considerations for Sub-Ghz Multilayer Microstrip Antenna for Near Ground Communication Links in Rural Areas(Ieee, 2017) Bilgin, Gulsima; Yilmaz, Vadi Su; Aydin, Elif; Kara, Ali; Department of Electrical & Electronics Engineering; Electrical-Electronics EngineeringThis paper presents some preliminary results of design and development of sub-GHz multilayer microstip antenna for use in near ground communication applications. In design stage of the antenna, iterative approach was applied. Firstly, a two layer microstrip antenna design process is presented. Next, the corners of the patch were cut, and a vertical wall on all sides of the antenna were introduced. In this way, both the size and resonant freqeuncy can be tuned. Moreover, as an application specific requirement, it is intended to embed this antenna into a metal box in order to protect it from man-made and natural environmental effects. This was also studied, and effects of the embedding ground on the antenna characteristics were examined. It is shown that the designed antenna provides -27dB resturn loss, and 7.3dB peak gain at 915MHz with the dimension of 150x200x13mm. Some preliminary measurements have proven the simulations.Conference Object Citation - WoS: 12Design of a Robotic Bicopter(Ieee, 2019) Albayrak, Ozge Beyza; Ersan, Yagmur; Bagbasi, Aysen Suheyla; Basaranoglu, Ahmet Turgut; Arikan, Kutluk BilgeThis article presents a Bicopter type of a flying robot with two rotary-wing units which are placed in a tandem form on the chassis. The rotors are tilted by the aid of the tilt mechanism. Cascaded type of PID controllers are designed on the dynamical models for the attitude and altitude dynamics. The simulated control systems are implemented and tuned on the Naze32 flight controller which is connected to a Raspberry Pi single board computer for real-time applications. The real-time performance is monitored and evaluated during the tests and it is seen that the system is suitable for indoor type of robotic applications.Conference Object Citation - WoS: 4Citation - Scopus: 6A Reinforcement Learning Algorithm for Data Collection in Uav-Aided Iot Networks With Uncertain Time Windows(Ieee, 2021) Cicek, Cihan TugrulUnmanned aerial vehicles (UAVs) have been considered as an efficient solution to collect data from ground sensor nodes in Internet-of-Things (IoT) networks due to their several advantages such as flexibility, quick deployment and maneuverability. Studies on this subject have been mainly focused on problems where limited UAV battery is introduced as a tight constraint that shortens the mission time in the models, which significantly undervalues the UAV potential. Moreover, the sensors in the network are typically assumed to have deterministic working times during which the data is uploaded. In this study, we revisit the UAV trajectory planning problem with a different approach and revise the battery constraint by allowing UAVs to swap their batteries at fixed stations and continue their data collection task, hence, the planning horizon can be extended. In particular, we develop a discrete time Markov process (DTMP) in which the UAV trajectory and battery swapping times are jointly determined to minimize the total data loss in the network, where the sensors have uncertain time windows for uploading. Due to the so-called curse-of-dimensionality, we propose a reinforcement learning (RL) algorithm in which the UAV is trained as an agent to explore the network. The computational study shows that our proposed algorithm outperforms two benchmark approaches and achieves significant reduction in data loss.Conference Object Citation - WoS: 3Citation - Scopus: 11Towards Modeling Patterns for Embedded Software Industry: Feedback From the Field(Ieee, 2018) Akdur, Deniz; Demirors, Onur; Say, BilgeThe analysis, design, implementation and testing of software for embedded systems are not trivial. Software modeling is a commonly used approach in the embedded software industry to manage complexity of these phases. The modeling approaches vary since the characteristics of modeling such as its purpose, the medium type used, the lifecycle phase used, differ among systems and industrial sectors. Our previous research identified and defined the modeling approach patterns in embedded software development projects based on quantitative data. In this paper, to validate and improve the pre-investigated pattern set, we present a series of semi-structured interviews over eight months with 53 embedded software professionals across a variety of target industrial sectors and roles. With the help of these interviews, the different modeling approach patterns in embedded software development were better understood and the hidden patterns not evident in the previous study were identified along with a documentation of personalized modeling experiences.Conference Object An Rfid Based Location Finding and Tracking With Guidance(Ieee, 2008) Oktem, Rusen; Aydin, Elif Uray; Cagiltay, Nergiz ErcilThis paper tackles an RFID based location finding and tracking system. The system is an integral part of a navigation aid being developed for guiding visually disabled people in a store. The aid is composed of a portable hardware interface unit, a standalone RFID unit, and a central processing unit. The units interact via wireless communication to locate the position of the user in a known indoor environment and tracking his/her movement. An active RFID tag helps to estimate the location of a user and the user is guided to follow a route accordingly, via a tactile compass. The system uses RF signal strengths and is based on Bayes Decision Theory. Initial simulation results with the system prove promising for location finding and tracking, especially when the tracked person is guided by a system.Conference Object Optimization of modeling parameters of of a direct dimethyl ether fuel cell (DDMEFC)(Ieee, 2019) Alpaydin, Guvenc Umur; Colpan, C. Ozgur; Devrim, YilserDirect alcohol fuel cells are one of the suitable candidates for sustainable power generation in portable applications. Among the different alcohol types that can be used in these fuel cells, DME, which is almost non-toxic at room temperature and easy to liquefy, and has a molecular structure similar to methanol, is one of the suitable options. For this reason, many studies have been carried out to develop direct dimethyl ether fuel cell (DDMEFC). Mathematical modeling studies also play an important role in the development of DDMEFC since they enable the understanding of the performance of the fuel cells more thoroughly. In this study, a model has been developed by using the principles of conservation chemical species and electrochemistry. A modeling study was performed using MATLAB. The values of some modeling parameters were estimated using the genetic algorithm optimization technique.Conference Object An Investigation About Process Matchmaking Performances of Unstructured and Decentralized Digital Environments(Ieee, 2007) Cakir, Bugra; Kilic, HurevrenEfficient matchmaking is an important problem in unstructured and decentralized digital environments. We report the results of simulations of these environments and provide measurements of match performance focusing on unstructured and decentralized environments. In the study, different environment models including P2P (Hypergrid, Gnutella with/without ultrapeer); small-world (Watts-Strogatz); heavy-tailed and random versions of Autonomous System Waxman model showing power-law distribution property; random and 2D-Grid are considered. The flooding mechanism enabling process encounters for match purposes is uninformed Breadth-First-Search. Simulations show that the matchmaking performance of random environment outperforms the others for almost all different problems and time-to-live settings. On the other hand, the total cost of small world environment model is the highest for almost all setups.Conference Object Density-Aware Outage in Clustered Ad Hoc Networks(Ieee, 2018) Eroglu, Alperen; Onur, Ertan; Turan, MehmetDensity of ad hoc networks may vary in time and space because of mobile stations, sleep scheduling or failure of nodes. Resources such as spectrum will be wasted if the network is not density-aware and -adaptive. Towards this aim, distributed and robust network density estimators are required. In this paper, we propose a novel cluster density estimator in random ad hoc networks by employing distance matrix. Monte-Carlo simulation results validate the proposed estimator. The accuracy of the estimator is impressive even under a high amount of distance measurement errors. We also propose a network outage model and a transmit power adaption technique that are density-aware. The results indicate the necessity of the density-aware solutions for making network performance better from capacity, coverage and energy conservation viewpoints.Conference Object Citation - WoS: 1An Industry Sponsored Undergraduate Research (ur) Experience: Preliminary Study on Fulfillment of Program Outcomes and Industry Requirements(Ieee, 2014) Kapusuz, Kamil Yavuz; Kara, AliThis study presents educational results of an industry sponsored undergraduate research (UR) project. The aim of the study is to show how such project works contribute to students in acquiring qualifications or skills necessary by the industry, and abilities regarding with program outcomes of accreditation organisations. The study is based on quantitative (surveys) and qualitative (self descriptions) data collected from senior students who worked in 9 months UR project sponsored by a company in Radio frequency (RF) and Communications domain. The preliminary results showed that an industry sponsored undergraduate research project may serve to both short term (industry requirements) and longer term (program outcomes) expectations in undergraduate curriculum of engineering departments.
