<abstract><title style='display:none'>Abstract</title> The paper presents issues related to the cooperative communication in wireless networks. Cooperative communication involves the use of mobile terminals as relay stations to improve the transmission quality, improve network performance and reduce energy consumption. It is also possible to use several different data transmission standards. The paper presents the methods used to implement cooperative communication. The types of cooperative communication networks are also presented.</abstract>

Overview of Cooperative Communication Methods

<abstract><title style='display:none'>Abstract</title> The article presents the impact of major maritime accidents on the development of international regulations concerning the safety of navigation and environmental protection of the seas and oceans. It contains analysis of the reasons and consequences of maritime disasters like the accidents of: ‘Titanic’, ‘Torrey Canyon’, ‘Amoco Cadiz’, ‘Herald of Free Enterprise’, ‘Exxon Valdez’, ‘Estonia’, ‘Erika’ and ‘Prestige’ as well as international agreements established in order to prevent this type of accident in the future or, at least, limit their consequences.</abstract>

The Impact of Major Maritime Accidents on the Development of International Regulations Concerning Safety of Navigation and Protection of the Environment

<abstract><title style='display:none'>Abstract</title>The article presents the analysis of the threats to Polish Navy ships resulting from the development by the Baltic Sea countries of missile systems or turbojet missiles. The most popular varieties and types of missiles that could be used against Polish Navy vessels were described and classified taking into account mainly the potential of the Baltic Fleet of the Russian Federation (BF FR), as well as an analysis of the latest global trends in the area of counteracting these missiles. The article presents the conclusions drawn from exemplary simulations of the attack of modern anti-ship missiles. The article also contains references to the ways of determining the probability of avoiding a rocket attack and the measure of the effectiveness of self-defence of attacked ships. The work contains conclusions regarding desirable traits from the systems of self-defence of ships on the modern battlefield with particular emphasis on the character of the Polish Navy. The article presents an analysis of the threats to ships of the Polish Navy, resulting from the development in the Baltic Sea countries, missile/turbojet anti-ship systems. Were described and classified most popular varieties and types of missiles applicable to fight Polish Navy ships and described latest global trends counteracted against these missiles. The article presents the conclusions drawn from exemplary simulations of the attack of modern anti-ship missiles. The article also contains references to the ways of determining the probability of avoiding a rocket attack and the measure of the effectiveness of self-defence of attacked ships. The work contains conclusions regarding desirable traits from the systems of self-defence of ships on the modern battlefield, with particular emphasis on the nature of the Polish Navy.</abstract>

Flying Means of Attack of Ships, Possible to Be Used by a Potential Enemy—Analysis of the Threats for Ships the Polish Navy

<abstract><title style='display:none'>Abstract</title>Due to the growing interest in the problems of cooperation among unmanned vehicles, in the article the proposition of the system for launching a mini unmanned aerial vehicle (mini-UAV) from an unmanned surface vehicle (USV) has been presented. The solution differs from the previously used in this that instead of the commonly used rotorcrafts it concerns the ability to start the mini aircraft with the help of pneumatic or rubber launcher. The results of the computer simulation have con-firmed the possibility of implementation of that kind of system.</abstract>

The Prospect for the Launche of a Mini Unmanned Aerial Vehicle from an Unmanned Surface Vehicle

<abstract><title style='display:none'>Abstract</title> This article presents the results of research based on analysis of ice conditions on the Arctic Sea in recent years and consequences of these changes. The Arctic ice extent are changed due to global warming. Reducing the ice surface leads to intensification of the navigation of the waters of the Arctic Sea, resulting in a significant reduction of the distance between the ports of Europe and East Asia and the North and South Americas. This phenomenon is conducive to the opening of new shipping routes leading through the Arctic Sea. After the entry into force of 1st January, 2017 The International Code for Ships Operating in Polar Waters (Polar Code) is expected to improve the safety of conducting the navigation of the waters. Analysis of maritime accidents in the Arctic waters shows that the number of accidents has a growing trend, however, last year brings them a significant decreasing.</abstract>

Safety of Navigation in the Arctic

<abstract><title style='display:none'>Abstract</title>Eddy current magnetic signature is, together with magnetization of ferromagnetic hull, mechanisms and devices on board, corrosion related and stray field sources one of the main sources of ship’s magnetic signature. Due to roll, pitch and yaw of the ship in external magnetic field, eddy currents are induced in conducting materials on board ship, mainly in conducting hull. Flow of those currents is a source of magnetic field around a ship. Principal eddy current component is related to roll movement as it depends on rate of change of external field which is the highest for roll. Induced currents have both in-phase and quadrature components. Magnitude of the eddy current magnetic field can have significant effect on total magnetic field signature after degaussing for ships such as mine sweepers and mine hunters. Paper presents calculations and simulations as well as measurements of model and physical scale model made of low magnetic steel performed in Maritime Technology Center. Contribution of eddy current magnetic field in total field in low roll frequencies has been estimated.</abstract>

Simulations and Measurements of Eddy Current Magnetic Signatures

<abstract>
<title style='display:none'>Abstract</title>
In the paper review of unmanned underwater vehicle (AUV) is presented. The description of main systems is depicted with focus on autonomous single vehicle as well as a swarm. As a consequence of development of AUV technology, research centers are focused on issues related to increasing the degree of their autonomy. Nowadays, mostly navigation and communication as well as high-efficient propeller systems are being developed. There are problems linking this issues. Their solutions includes development of new control laws containing algorithms to prevent collisions - for unmanned vehicles with elements of the underwater environment and for several underwater vehicles cooperating with each other in a swarm.
</abstract>

Directions of Development of the Autonomous Unmanned Underwater Vehicles. A Review

<abstract>
<title style='display:none'>Abstract</title>
The continuous development of autonomous and unmanned technology is accelerating the adoption of unmanned vessels for various maritime operations. Despite the technological developments there is still a lack of clear regulatory and organizational frameworks for testing and exploiting the potential of unmanned surface vessels (USVs) in real-world maritime conditions. Such real-world testing becomes ever more complex when operating in multiple nations territorial waters. In May 2019 USV ‘Maxlimer’ crossed the North Sea from the United Kingdom to Belgium and back, carrying goods, to demonstrate the ability of unmanned surface vessels to interact with real marine traffic in an uncontrolled environment. The paper presents this mission in light of the current state of marine autonomy projects as well as the regulatory works conducted by various organizations worldwide.
</abstract>

The Assessment of Unmanned Vessel Operation in Heavy Traffic Areas. Case Study of the North Sea Crossing by Unmanned Surface Vessel Sea-Kit

<abstract>
<title style='display:none'>Abstract</title>
The presence of an outlier at the starting point of a univariate time series negatively influences the forecasting accuracy. The starting outlier is effectively removed only by making it equal to the second time point value. The forecasting accuracy is significantly improved after the removal. The favorable impact of the starting outlier removal on the time series forecasting accuracy is strong. It is the least favorable for time series with exponential rising. In the worst case of a time series, on average only 7 % to 11 % forecasts after the starting outlier removal are worse than they would be without the removal.
</abstract>

Impact of Starting Outlier Removal on Accuracy of Time Series Forecasting

<abstract>
<title style='display:none'>Abstract</title>
The article presents a simulation of a ship running aground. It introduces the analytical description, as well as the methodology of carrying out strength calculations when creating engineering tasks related to the topic. It shows the state of stresses and deformations of the hull of a modern minehunter after a collision with the bottom for two immersion depths. Research and development opportunities for future considerations are highlighted in the conclusions.
</abstract>

The Analysis of the Strength of the Ship’s Hull After Running Aground

<abstract>
<title style='display:none'>Abstract</title>
A fast-and-flexible method of ARIMA model optimal selection is suggested for univariate time series forecasting. The method allows obtaining as-highly-accurate-as-possible forecasts automatically. It is based on effectively finding lags by the autocorrelation function of a detrended time series, where the best-fitting polynomial trend is subtracted from the time series. The forecasting quality criteria are the root-mean-square error (RMSE) and the maximum absolute error (MaxAE) allowing to register information about the average inaccuracy and worst outlier. Thus, the ARIMA model optimal selection is performed by simultaneously minimizing RMSE and Max-AE, whereupon the minimum defines the best model. Otherwise, if the minimum does not exist, a combination of minimal-RMSE and minimal-MaxAE ARIMA models is used.
</abstract>

Arima Model Optimal Selection for Time Series Forecasting

<abstract><title style='display:none'>Abstract</title>Jamming of GNSS signals is lately treated as essential threat for GNSS users. It is especially dangerous in the face of common usage of GPS-like systems in everyday life, and the great belief of everyday users in the truth of devices indications. In spite of the legal prohibition of using them, jammers are commonly accessible, especially in the Internet. Last years showed however that such threat generated purposely also some governments, what is clearly visible in armed conflicts, and during military exercises. Of course this creates the great threat for civilian users if will be in the vicinity.Applications and services based upon GNSS are becoming increasingly embedded in modern society, so community have now become critically dependent upon their correct operation. This refers positioning first of all, but telecommunications networks, power grids, financial transactions, whole world of logistics are dependant as well. The main users of GNSS, both professional and non-professional smartphones users are not prepared on such situation, and usually have no technical possibilities to detect of jamming. For operators of critical installations, for example seaports, or airfields, the detection of jamming cases is extremely important. It can be provided with special devices, which are usually based on specific antennas, and deep analysis of signal. In this paper experiments in detection of the jamming with helical antennas are discussed</abstract>

Possibilities of Detection of the Jamming of the GNSS Receiver with the Helical Antenna

<abstract><title style='display:none'>Abstract</title> Due to the safety reason, the ship movement on the littoral area should be monitored, tracked, recorded and stored. Automatic Identification System (AIS) is the perfect tool to ensure this requirement. The limit probability for the AIS dynamic data availability can be limited by the lack of Global Position System (GPS) signal, heading (HDG) and rate of turn (ROT) data in position report. Availability of data link is an additional limitation. For this purpose, it is possible to attach the Discrete Kalman filter (KF) for the position, and course estimation. Coordinate estimation in the absence of a transmission link can improve the quality of AIS service at Vessel Traffic Service (VTS) stations. This article presents Kalman filtering algorithm to improve the possibilities of ship motion tracking and monitoring in the TSS (Traffic Separation Scheme) and fairways area. Only 39 iterations were presented to familiarize how the Kalman filter algorithm works. The archival data from 2006 were used deliberately. During that time, there were problems with the AIS availability service. With the use of measurements series from those years, it is easier to observe the effectiveness of Kalman filter in absence of AIS data.</abstract>

Automatic Identification System (AIS) Dynamic Data Estimation Based on Discrete Kalman Filter (KF) Algorithm

<abstract><title style='display:none'>Abstract</title>In this review it is presented the insight of challenges faced by all branches of industry in the new age, and especially the maritime industry, strive for sustainable development, better energy control, use of materials with functional properties such as shape memory, all in the direction of increasing safety and comfort. Therefore, the development of new materials with shape memory, which is associated with the introduction of optimized production and the achievement of better functional properties. This leads to new applications in different systems and possible use on devices, which meet the rigorous requirements of the modern industry.The research into new materials with shape memory effect and their applied use in maritime is a challenge that many researchers have encountered in recent decades, and this is why in this paper we look at the basic engineering aspect of these materials and their current as well as future applications in the maritime industry. An overview of several innovations that testify shape memory effect and superelasticity in different maritime fields will be presented in this review.</abstract>

Materials with Shape Memory Effect for Applications in Maritime

<abstract><title style='display:none'>Abstract</title> This article presents a summary of years of research of corrosion resistance and corrosive-stress marine materials and their joints. Aluminium alloys and marine steels including the austenitic have been the subject of research in terms of resistance of these materials for electrochemical corrosion in sea environment. Under certain conditions austenitic steels and aluminium alloys show low susceptibility to corrosion due to the protective oxide film which form itself spontaneously on their surfaces and which became a part of monitoring corrosion of these materials. Unfortunately, the real conditions of ship structures loads and the impact conditions of the sea environment show the need to search for the new materials or to modify those already used in order to increase their corrosive-stress resistance. The welded joints of the above mentioned materials were the special subject of corrosive research and nowadays their friction stir welding joints. Modifying the structure of the origin materials by the alloyed elements, changing the parameters of the heat treatment, using the suitable protective paints or selection of the proper adhesives to connect these materials are the methods used in the following research to increase the corrosion resistance of the aluminium alloys. However, monitoring corrosion based on the patent US 2167 23 states a particular point of these research.</abstract>

Study of the Corrosion Resistance of Ship Aluminium Alloys

<abstract><title style='display:none'>Abstract</title> The paper presents the issues associated with the domestic construction of unmanned surface vessels, which are in the limelight of western counties as one of the reinforcing elements of internal security and maritime economy. Also discussed are some experiences from construction of the first such vessel named ‘Edredon’, and on the example of Gdansk Bay and the seaport of Gdynia a number of selected tasks that can be carried out by a vessel in the process of state’s maritime services protection, and in monitoring and protection of the seaports and objects of critical infrastructure. Moreover, the directions for further development (autonomous vessels, in particular) that can be accomplished in a short period of time, based on domestic scientific abilities and shipbuilding industry are indicated.</abstract>

Application of Domestic Unmanned Surface Vessels in the Area of Internal Security and Maritime Economy — Capacities and Directions for Development

<abstract><title style='display:none'>Abstract</title> The paper presents results of research based on analysis of ice conditions in the Baltic Sea and in the Puck Bay. Analyses are concerned on the last century the maximum ice extents in the Baltic Sea (1915-2015) and ice conditions in the Puck Bay (1986-2005). Ice conditions in the Baltic Sea are generally of average intensity and depend mainly on the type of winters (mild, average/ normal and severe), however, the Baltic bays and gulfs cover the sea ice almost every year. The average ice extent in the Baltic Sea during typical winters, the ice extent in the Baltic Sea during winters in years from 1915 to 2015 and the average time limits the occurrence of the first ice, number of days with ice, ice thickness, terms the disappearance of the last ice in the Puck Bay together with examples of ice forms are presented in this paper. The phenomenon of ice has a significant impact on human activities in the sea, have an effect on weather and climate, plant and animal life, fishery and ports activities and the safety of navigation.</abstract>

Analysis of Ice Conditions in the Baltis Sea and in the Puck Bay

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Maritime Technical Journal

formerly Scientific Journal of Polish Naval Academy

 Scientific Journal of Polish Naval Academy has been published since 1959 (in electronic version since 2004). Every year four volumes are published. In...

 Scientific Journal of Polish Naval Academy has been published since 1959 (in electronic version since 2004)....