Journal of Naval Sciences and Engineering

27-42

Authors: Deniz KUMLU, Batuhan GÜNDOĞDU

The clutter problem in ground penetrating radar (GPR) images highly effects the performance of target detection ratio. Various methods have been proposed for clutter suppression purposes in the GPR literature. They can be mainly grouped as low rank, low rank and sparse and tensor-based decomposition methods. Principal component analysis (PCA) and robust principal component analysis (RPCA) are classicle approaches and could be classified as low rank and low rank/sparse decomposition methods, respectively. Recently proposed tensor-based methods provide an alternative perspective of solving the low rank and sparse decomposition to handle challenging situations such as shallowly buried objects or rough surface situations. Motivated by the performance of Tensor-based methods, we propose a new pre-transformation step for tensor robust principal component analysis (TRPCA) and compare it with the PCA and RPCA methods over a simulated GPR dataset. Our proposed method outperforms the classical PCA and recent RPCA methods both visually and quantitatively in terms of clutter removal.

77-102

Authors: Muhammet DEVECİ, Nezir AYDİN, Ali Osman KUSAKCI

The number of passengers in public transport has decreased significantly in major cities around the world due to COVID-19. As residents of many countries work from home, they have avoided public transport to minimize their exposure to the outbreak and have changed their way of traveling within their cities due to major changes in local public transport services. Istanbul is one of the cities most affected by the pandemic in terms of the daily number of passengers using public transportation. For the first time since the pandemic started in Istanbul, the use of urban public transportation has decreased by more than 90 percent. The aim of this study is to examine the measures taken in Istanbul public transport in order to prevent the spread of the coronavirus pandemic. In addition, the trends in public transport and inter-modes demands during COVID-19 are analyzed. The results showed that COVID-19 measures to protect the health of passengers in Istanbul public transport are in line with global practices during the initial stage of the pandemic.

131-163

Authors: Emrah KÖKSALMIŞ, Serhat AYDIN

With the impact of the COVID-19 pandemic continuing to be felt globally, it is essential that people quickly adapt to a new virtual business landscape, in order to continue to provide a valuable conference experience. E-conference, in other words web conference or virtual conference, is an online conference that involves people participating in a conference through a virtual environment on the web, rather than meeting in a physical location. The objective of this paper is to inspect several reasons of behavioural intention to use an e-conference system by utilizing the modified technology acceptance model (TAM). Together with primary elements of TAM, in this particular paper, additional constructs such as satisfaction, time, price savings, technical support, mobile anxiety, social influence and convenience are taken into account. Total of 203 questionnaires is gathered through academicians in Turkey. To evaluate the data and examine the proposed hypotheses, the Structural Equation Modeling (SEM) methodology is implemented by utilizing SmartPLS 3.2.7. The results indicate that convenience, mobile anxiety, satisfaction, perceived usefulness and social influence are significantly predicting the behavioural intention. This paper enables theoretical and practical implications for authorities seeking to implement an e-conference.

181-203

Authors: Murat Kağan KOZANHAN

Piracy is an illegal act that has existed since the beginning of the sea trade. However, efforts continue to be made to or to commit terrorist acts in the seas through piracy activities today. Piracy and terrorist acts at sea threaten/affect not only commercial security but also international maritime security and therefore international security. On October 7, 1985, the hijacking of the Achille Lauro ship brought up the necessity of making an international agreement and cooperation of states to prevent illegal acts at sea, and the Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation (1988 SUA Convention) and its Additional Protocol were signed. The terrorist acts of September 11, 2001, besides the acts of piracy, also led to the questioning of terrorism and international maritime security in this context and the actions that can be done at sea on 14 October 2005 were rearranged. Within this context, the development of the 1988 SUA Convention was examined in this study, and then the intervention made by the Russian Federation based on the SUA Convention and its Additional Protocol to the Arctic Sunrise ship, which operates on behalf of the Greenpeace Organization, and evaluations were made within the framework of the decisions made as a result of the case being brought to the judiciary.

117-141

Authors: Muhammet DEVECİ, Yusuf KUVVETLİ, İbrahim Zeki AKYURT

In recent years, with the increase in investment in countries' military expenditures, the importance of decision-making problems in the military has gradually increased. There are various uncertainties such as vagueness, imprecise or ambiguous in decision-making problems. Decision making is the process of evaluating environmental factors from a holistic perspective, identifying problems and possible alternatives, making a systematic assessment, and identifying the most appropriate decision among them. The aim of this study is to investigate various types of fuzzy set that can be used in military problems under uncertainty. In addition, a detailed literature review of fuzzy decision making problems applied in the military are conducted.

171-192

Authors: Zeynep TAŞLIÇUKUR ÖZTÜRK, Abdullah Koray PEHLİVAN

In this study, GeKa Tempo B65 electrodes are used in the welding of high strength low alloy (HSLA) S355JR steel. It is aimed to increase the impact resistance of the electrodes at minus temperatures. In order to observe the mechanical properties of the materials, tensile, impact energy test and CTOD test are performed. Implicit electric arc welding is chosen as the welding method. Electrodes with three different compositions and grain structures are prepared for welding. Optical microscope is used to observe the surface images of the weld seams. It is observed that the grain structure of the sample, the amount of alloying elements and the heat input during the welding of the sample significantly affect the impact resistance of the welded samples.

217-237

Authors: Batuhan GÜNDOĞDU, Deniz KUMLU

Semaphore flag signaling is a visual communication system used by Naval vessels when the radio emissions are under strict control during electronic warfare. This paper presents an autonomous semaphore flag signaling recognition system that translates the RGB images into letters with a high performance at a low cost. A dataset is created for the semaphore flag signals for the English alphabet and the relative angles of the flags are acquired via morphological operations. The summarization of the flag locations is conducted with three methods: binary erosion the shrinking, k- means clustering and hierarchical agglomerative clustering. The resulting features with low dimensionality are then classified with support vector machine classifier with polynomial kernel. The cross-validation experiments show that the proposed methodology yields 99.76% accuracy, with no need for a Kinect sensor and computationally expensive neural network training that requires GPUs, as proposed by the similar works in the literature.

25-44

Authors: Doç. Dr. Atilgan ALTINKÖK, Doç. Dr. Murat OLUTAŞ

The use of Transparent Conductive Oxide (TCO) thin films in technology has increased in the last decades. These materials have good electrical conductivity visible light transmittance simultaneously. TCOs have many technology applications such as thin film transducers (TFTs), conductive electrodes, capacitors, sensors, electrochemical devices. Although indium tin oxide (ITO) is the most common semiconductor among these materials, studies on N-type indium-gallium-zinc oxide (IGZO) that better electrical properties (electron mobility µFE>10 cm2 /V.s) cm2 / Vs) have increased in recent years. In this study, IGZO thin films are produced which have a very homogeneous amorphous structure via using thermal evaporation system on glass substrates. Structural characterization was carried out by atomic force microscopy and scanning electron microscopy on IGZO thin films for various thickness and annealing temperatures. Transmittance and thickness measurements were performed using UV-VIS spectroscopy and profilometer for the investigation of optical properties, respectively. It is seen that grain size grows and grain boundaries decreases when annealing temperature is increased. This results in reduced roughness and increased optical transmittance and energy gap (Eg).

71-83

Authors: Doç. Dr. Atilgan ALTINKÖK

NbN thin films are very useful superconducting materials for the electronic devices. Using sputter deposition technique is a cheap alternative to produce of NbN thin films on glass or SiO for the technology applications. The NbN films was coated on glass and SiO/Si substrates by DC magnetron sputtering technique. Pure Nb target was used the production of NbN thin films in different compositions of Argon and nitrogen gases. The effects of different substrate temperatures, sputtering power and, various ratios of Nitrogen/Argon gases were investigated on Superconducting Critical Temperature (Tc). It is seen that increasing the substrate temperature or sputtering power resulted in increased on the Tc. Thereby optimum condition values are deduced by the Residual Resistance Ratio (RRR) calculation and resistance-temperature (R-T) curves. It is observed that the substrate temperature and the flux of nitrogen gas effect (111) preferential orientation during the deposition, whereas the critical temperature of the thin films is affected by the of deposition chamber vacuum. Tc is also highly dependent on the Nitrogen and Argon pressures on sputtering deposited NbN films.

113 - 128

Authors: Özgenur AKTAN

The purpose of this review is to critically evaluate Peter Leeson’s paper in which he argues that piracy as profit-seeking criminal activity may produce socially desirable outcomes and achieve a social order and then, concludes that criminals’ self-interested and profit-seeking activities are capable of producing public benefits in the context of invisible hand. More precisely: the purpose is to critically discuss and evaluate Leeson’s general conclusion, line of reasoning and to present counter-arguments in the context of invisible hand and pirates’ relative racial tolerance policy towards black sailors in their crews. Leeson tries to investigate the political economic and social impacts of piracy in the late seventeenth and early eighteenth century and argues that black crew members’ economic and social status in pirate ships were more progressive compare to the legitimate merchant ships. Leeson reads black crew members’ status in pirate ships as an improvement in racial equality, economic and social justice. Therefore, he concludes that self-interested and profit-seeking criminal activities are capable of producing socially laudable outcomes. In contrast to Leeson, the argument in this review is that self-interested and profit-seeking criminal activities are not capable of producing socially laudable outcomes.

159 - 172

Authors: Elif BOZKAYA

Energy saving technologies for smart vehicles have great importance because of decreasing total energy consumption. It is estimated that the cost of energy will increase in the near future. Here, Road Side Units (RSUs) are the dominant contributing components to the overall energy consumption in Intelligent Transportation Systems (ITS). This paper investigates the energy efficiency of RSUs by proposing an energy management model for ITS. Energy efficiency can be achieved if as many as possible RSUs switch off while maintaining an acceptable quality of service. The aim is to present a way to improve total energy efficiency by scheduling RSUs with a switching on/off model so that total energy consumption of RSUs can be managed.

21-38

Authors: Serkan KARAKAŞ, Mehmet KIRMIZI

A large part of the world energy requirement is provided from offshore oil and gas fields. The Kashagan site in the Northern Caspian Sea has one of the largest known reserves and marine operations are important for the continuation of activities regarding oil and gas production in area. However, the geographical features of the region make the maritime-related activities difficult. There are different types of marine equipment in operation within the scope of the Kashagan project and one of the most widely used vessel is Multi-Purpose Tugboat / AHT (Anchor Handling Tug). As far as the requirements of the task are concerned, the geographic challenges of the region (especially low water depth) should be taken into consideration when selecting the AHT by the management. In this study, the optimum AHT vessel will be selected to operate in the North Caspian Sea by utilizing MOORA (Ratio and Reference Point approaches) and TOPSIS methods and the concordonce among three methods will be tested by Kendall’s Coefficient of Concordonce (Kendall’s W).

63-85

Authors: Kadir ATASEVEN, Hüseyin YILMAZ

Survivability of a naval surface ship is defined as the durability of the ship to a defined weapon threat, and, the degree of its ability to maintain at least the basic safety and operability of the ship, and is composed of a combination of the ship's susceptibility, vulnerability and recoverability. The empirical stability criteria laid down by Sarchin and Goldberg in 1962 are used to assess the survivability of warships. In recent years, along with deterministic rules, the probabilistic approach that has been made mandatory for the passenger / Ro-Ro ships by the International Convention on the Safety of Life at Sea (SOLAS) have been used for warships. In this study, the fundamentals of using the concepts of the deterministic and stochastic approaches and the concept of probability used in assessing the survivability of warships are emphasized.