rss_2.0Scientific Journal of Polish Naval Academy FeedSciendo RSS Feed for Scientific Journal of Polish Naval Academy Journal of Polish Naval Academy 's Cover of Nakagami Distribution Parameters in Describing a Fading Radio-Communication Channel<abstract><title style='display:none'>Abstract</title><p> This article presents a review of issues related to the estimation of Nakagami distribution parameters. This distribution is often used for modeling transmission in a fading radio-communication channel, and in addition it well approximates other distributions.</p></abstract>ARTICLE2016-03-31T00:00:00.000+00:00LTE as a Trunking -Dispatch System<abstract><title style='display:none'>Abstract</title><p> In the paper solutions of trunking-dispatch systems based on the LTE system are presented. The solution in the form of separate LTE/TDD trunking system is discussed, and the concept of the LTE/FDD trunking system operating in the infrastructure of public, mobile networks is characterised.</p></abstract>ARTICLE2016-03-31T00:00:00.000+00:00Real -Time Generator of AIS/ARPA/GPS Data<abstract><title style='display:none'>Abstract</title><p> The paper presents a real-time generator of AIS/ARPA/GPS position data in the standardized NMEA 0183 text format. Position data are produced by a set of various types of ships simulated on the Polish part of the Baltic Sea and are generated on defined IP/UDP addresses and RS-232 ports. In the simulation an extensive set of input parameters is taken into account including the number of particular types of ships, their dimensions, speed as well as parameters of AIS equipments, ARPA radars and GPS receivers. The paper describes the architecture and implementation of the generator. Additionally, it demonstrates the application of the developed generator to test the software developed for the Polish Border Guard.</p></abstract>ARTICLE2016-03-31T00:00:00.000+00:00Adaptation of the Support Frame of the Cooling Skids System for Use in Maritime Transport<abstract><title style='display:none'>Abstract</title><p> The article presents calculations of the strength of a support frame Skid Cooling units used on oil rigs. The complexity of the equipment does not allow for efficient FEM modeling of such structures. It indicates how to the simplify the model so that the calculations can accepted by the American Bureau of Shipping (ABS).</p></abstract>ARTICLE2016-03-31T00:00:00.000+00:00Bioterrorism — Characteristics and Possibilities of Prevention<abstract><title style='display:none'>Abstract</title><p> In the paper bioterrorist threats have been presented. Historical background and possible methods of attacks have been described. The most dangerous pathogens and disease entities have been classified. Selected methods of detection and identification of biological weapon have been presented. The wireless system for threats monitoring - developed at Gdansk University of Technology - has been described.</p></abstract>ARTICLE2016-03-31T00:00:00.000+00:00Analysis of Impact of Disruptions Coming from a Ship on the Accuracy of Determining the Location of the Tracked Air Target by The Modified Optoelectronic Scanning and Tracking Ir Seeker<abstract><title style='display:none'>Abstract</title><p> The paper presents the results of research whose aim was to specify the impact of disruptions coming from the movement of a ship on the accuracy of determining the location of the tracked target by the modified, optoelectronic scanning and tracking seeker (OSTS). The basic task of OSTS consists in detecting and then tracking closely the detected air target, emitting infrared radiation.</p></abstract>ARTICLE2016-03-31T00:00:00.000+00:00Assessment of the Possibility of Using Point -To-Point Radio L inks in the Mimo System for Constructing the Local Area Network Backbone<abstract><title style='display:none'>Abstract</title><p> The article presents the results of the research conducted to assess the possibility of replacing the wiring in the connection system of the local network backbone for constructing backup connections or for the localizations where architectonic conditions do not allow performing installation works related to structural wiring of a building. Testing laboratory environment has been developed using radio devices operating in the IEEE 802.11n standard. The paper reports the results of the transmission tests in the systems of point-to-point links using the MIMO technique to determine parameters of the data transmission performance-throughput and latency. The transfer tests in the MIMO system were conducted in the indoor and outdoor environment.</p></abstract>ARTICLE2016-03-31T00:00:00.000+00:00An Operational Calculus Model with the () - Symmetric Difference<p>The paper determines a non-classical Bittner operational calculus model, in which the derivative is understood as an -symmetric difference <italic>D<sub>m,n</sub></italic>{<italic>x</italic> (<italic>k</italic>)} := {<italic>x</italic> (<italic>k</italic>+<italic>m</italic>)− <italic>x</italic> (<italic>k</italic>− <italic>n</italic>). By considering an operation <italic>D<sub>m,n,b</sub></italic>{<italic>x</italic> (<italic>k</italic>)} := {<italic>x</italic> (<italic>k</italic>+<italic>m</italic>)− <italic>b</italic> (<italic>k</italic>)<italic>x</italic> (<italic>k</italic>− <italic>n</italic>), the formulated model has been generalized.</p>ARTICLE2020-12-31T00:00:00.000+00:00Mobile Wheeled Robot to Support the Task of the Alarm Sub - Unit<p>The article is a presentation, and detailed description of a mobile, vehicular robot whose task is to support the alarm sub-unit. The project was created in response to the increasing need for monitoring, and recognition of the areas. The robot’s interface was created with the use of integrated development environments for Python. The software implementation was possible due to a minicomputer Raspberry Pi 4 B. The robot’s frame is made out of components which are based on the main chassis. The robot is equipped with compatible sensors and cameras. Those, combined with the interface, are able to give a real-time preview of the area in which the robot is in.</p>ARTICLE2020-12-31T00:00:00.000+00:00Tracking of Unmanned Aerial Vehicles Using Computer Vision Methods: A Comparative Analysis<p>Tracking of small objects in any given airspace is an integral part of modern security systems. In these systems, there are embedded methods that employ the techniques based on either radio waves, or acoustic signals, or light radiation. The computer vision operation, springing from the light radiation-based technique, has prompted interest in its research. This operation has the advantage of being less expensive than radars and acoustic systems. In addition, it can solve complex security problems by detecting and tracking humans, vehicles, and flying objects. Therefore, this article evaluates the usefulness of the varying computer vision algorithms for tracking of small flying objects.</p>ARTICLE2020-12-31T00:00:00.000+00:00Doppler Effect in 2 × 2 to 4 × 4 Mimo Systems of Wireless Communication with Orthogonal Pilot Channel Estimation<p>The Doppler effect in 2×2, 3×3, 4×4 MIMO wireless communication systems with channel estimation is studied. The orthogonal pilot signal approach is used for the channel estimation, where the Hadamard sequences are used for piloting, along with the eight alternative orthogonal sets similar to the Walsh set. MIMO transmissions are simulated for 10 cases of the frame length and pilot symbols per frame by no Doppler shift to 1100 Hz Doppler shift with a step of 100 Hz. Based on the simulation, it is ascertained that MIMO transmissions of shorter frames are less sensitive to the Doppler effect. Despite increasing the number of antennas does not mitigate the Doppler effect, and the bit-error rate performance of 4×4 MIMO systems worsens faster than that of 2×2 MIMO systems, it is better to use the maximum number of antennas. The Doppler effect does badly worsen the performance at highway and express train speeds (100 km/hr, and faster), leaving only possibility to further shorten transmissions. This, however, decreases the data rate, but the respective accuracy-versus-data-rate tradeoff must be acceptable.</p>ARTICLE2020-12-31T00:00:00.000+00:00Possibilities of Detection of the Jamming of the GNSS Receiver with the Helical Antenna<p>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.</p>ARTICLE2020-12-31T00:00:00.000+00:00Determination of Dynamic Characteristics of Austenitic Steel to be Utilized in Fem Simulation and its Verification<p>This paper presents the dynamic mechanical properties of austenitic steel with improved durability, which is used in the construction of hulls of minesweepers, mine destroyers, submarines and other naval vessels. Dynamic tensile tests performed on the steel samples using a rotary hammer with a strain rate of up to 1000 s-1 allowed determination of elastic-plastic characteristics of the material in the form of a polynomial of Johnson-Cook constitutive model, taking into account the influence of strain rate and temperature. A characteristic of this type is utilized in numerical calculations in the CAE software. The obtained characteristics were experimentally verified by bending tests of flat samples with a drop-weight type impact hammer. Simultaneously numerical calculations were performed in order to compare the deformation state.</p>ARTICLE2018-06-29T00:00:00.000+00:00Report on Research with Biomimetic Autonomous Underwater Vehicle — Navigation and Autonomous Operation<p>The paper presents the second part of the final report on all the experiments with biomimetic autonomous underwater vehicle (BAUV) performed within the confines of the project entitled ‘Autonomous underwater vehicles with silent undulating propulsion for underwater ISR’, financed by Polish National Center of Research and Development. The report includes experiments on the swimming pool as well as in real conditions, that is, both in a lake and in the sea. The tests presented in this part of the final report were focused on navigation and autonomous operation.</p>ARTICLE2018-06-29T00:00:00.000+00:00Static Analysis of the Tubular Electromagnetic Linear Actuator with Permanents Magnets<p>In this paper a results of a static analysis of the tubular linear electromagnetic actuator is presented. The linear actuator consist of two parts: a cylindrical unmovable coils surrounded by a soft ferromagnetic case, and a runner made from sequence of permanent magnet with a soft ferro-magnetic gasket. In the first part of the paper the analytical method was performed for preliminary analysis. In the second part of the paper the more detailed analysis was depicted with using finite element method (FEM). The magnetic circuit shape and impact of selected dimensions on static characteristics is presented. Then the axial and radial electromagnetic force as a function of the runner dimensions were analysed.</p>ARTICLE2018-06-29T00:00:00.000+00:00Nonhomogeneous Stochastic Processes Connected to Poisson Process<p>Some generalizations of the Poisson process and their properties are presented in the paper. The non-homogeneous Poisson process allows to construct a probabilistic model describing the different kinds of accidents number. The nonhomogeneous compound Poisson process enables to describe mathematically the various types of accidents consequences. Theoretical results give possibility to anticipate the accidents number and their consequences.</p>ARTICLE2018-06-29T00:00:00.000+00:00Selected Decompression Procedures for Survivors Who Became Saturated in a Sunken Wreck<p>This article is one of the series dedicated to the <italic>DiveSMART Baltic</italic> project conducted to better coordination of international underwater rescue operations in the Baltic Sea. The project <italic>DiveSMART Baltic</italic> has received Flagship status.</p>ARTICLE2018-06-29T00:00:00.000+00:00Thrust Measurement of Biomimetic Underwater Vehicle with Undulating Propulsion<p>In the recent years, a dynamical development of an underwater robotics has been noticed. One of the newest group of underwater robots are biomimetic underwater vehicles. These vehicles are driven by undulating propulsion imitating fins of underwater creatures, e.g. a fish, a seal, etc.</p>ARTICLE2018-06-29T00:00:00.000+00:00Unmanned Surface Vehicles in Maritime Critical Infrastructure Protection Applications — LNG Terminal in Świnoujście<p>In order to first Baltic LNG terminal in Świnoujście construction, issues concerning maritime critical infrastructure protection as a part of Maritime Security appeared. With the increasing natural gas demand LNG terminal in Świnoujście could be a possible terrorist attack target as well as the LNG carriers crossing the choke point of Baltic Straits and sailing through the littoral waters of Polish and other Baltic counties coastline. Experts do not fully agree on possible effects and results of successful terrorist assault on LNG carrier at sea nor at harbor.</p>ARTICLE2018-06-29T00:00:00.000+00:00Review of Normative Documents Applicable in Polish Navy in the Field of Measurement and Minimalization of Ships Physical Fields<p>The article presents the general organization and operating principles of the national departmental standardization system. The characteristics of the tasks carried out in the area of defense and security, in the new formal, legal, and organizational conditions related to the passive defense of the Polish Navy ships are presented. In addition, the article contains a brief description of standardization documents in the area of national defense applied in the Armed Forces of Poland. One of the areas related to the passive defense and measurements of physical fields in the Polish Navy was also indicated.</p>ARTICLE2019-12-31T00:00:00.000+00:00en-us-1