Fibre reinforced concrete (FRC) presently utilized as a part of special structures subjected to dynamic loads for example airport pavements, expressways overlays, bridge decks and machine foundations. In most cases, FRC contains just a single kind of fibre. The utilization of at least two kinds of fibres in an appropriate mix can possibly improve the mechanical properties of concrete and result in performance synergy. The audit demonstrates that the blend of fibre allows a more powerful control of the dynamic crack development. This review analyses the components for synergistic impacts that gives direction on the fiber and matrix choice.
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.
Smart Cities are no longer just an aspiration, they are a necessity. For a city to be smart, accurate data collection or improvement the existing ones is needed, also an infrastructure that allows the integration of heterogeneous geographic information and sensor networks at a common technological point. Over the past two decades, laser scanning technology, also known as LiDAR (Light Detection and Ranging), has become a very important measurement method, providing high accuracy data and information on land topography, vegetation, buildings, and so on. Proving to be a great way to create Digital Terrain Models. The digital terrain model is a statistical representation of the terrain surface, including in its dataset the elements on its surface, such as construction or vegetation. The data use in the following article is from the LAKI II project “Services for producing a digital model of land by aerial scanning, aerial photographs and production of new maps and orthophotomaps for approximately 50 000 sqKm in 6 counties: Bihor, Arad, Hunedoara, Alba, Mures, Harghita including the High Risk Flood Zone (the border area with the Republic of Hungary in Arad and Bihor)”, which are obtained through LiDAR technology with a point density of 8 points per square meter. The purpose of this article is to update geospatial data with a higher resolution digital surface model and to demonstrate the differences between a digital surface models obtain by aerial images and one obtain by LiDAR technology. The digital surface model will be included in the existing geographic information system of the city Marghita in Bihor County, and it will be used to help develop studies on land use, transport planning system and geological applications. It could also be used to detect changes over time to archaeological sites, to create countur lines maps, flight simulation programs, or other viewing and modelling applications.
Construction surveying consist in overall surveying works performed at every stage of the construction and use of a building structure. The surveyor participates in the processes of designing, direct implementation, maintenance and use, as well as demolition of a building structure. Advanced surveying techniques, such as laser scanning and UAV photogrammetry, are being increasingly used to perform the surveyor’s tasks. The aim of this research paper was to analyze the Polish legal regulations for the possibilities of applying the above-mentioned techniques to carry out the surveying works which are subject to the obligatory submission to public administration authorities. The primary focus was placed on the type of the works associated with construction surveying. The conducted research studies confirmed the lack of appropriate guidelines that would clearly define the scope and method of using laser scanning and UAV photogrammetry in construction surveying. At the same time, it was demonstrated that both these techniques of spatial data acquisition were sufficiently accurate to perform plane and vertical land surveys pursuant to the legal acts currently in force in Poland, and they can be used at selected stages of construction surveying. Finally, the authors proposed some solutions that would make it easier for the surveyors to use laser scanning and UAV photogrammetry in standard surveying works.
Limestone has been commonly used in concrete for several decades. Moreover, calcium carbonate was used as a portion of cement content. Therefore cuttlebone powder, which is composed of a naturally occurring crystal form of calcium carbonate named aragonite, was used in concrete as a substitution of a portion of cement content in this research program for the first time. It led to the production of green concrete which is a type of concrete causes less harm to environment. 3, 5 and 7 percent of cement were substituted with cuttlebone powder. For this purpose, 4 concrete mix designs included 36 cubes, 4 cylinders and 4 prisms were casted. Results showed that weight of the specimens with cuttlebone powder was lower than control specimen. Moreover, by adding cuttlebone powder to concrete, slump increased. Although compressive and tensile strengths of the specimens with cuttlebone powder were lower than control specimen, but the specimen with 3% cuttlebone powder had adequate strength. Besides, three-point flexural strength of the concrete with 3% cuttlebone powder was higher than control specimen. It seems that by reducing water content of the specimen with cuttlebone powder to have similar slump to the control specimen, better performance of concrete can be achieved. So, this natural material can be used instead of a portion of cement to produce green concrete.
Accomplishment of basic services implementation with specific quality is one of the main challenges of the command and communication systems for modern maritime safety and defense. The specificity of the marine environment imposes the use of narrowband HF (High Frequency) and VHF (Very High Frequency) radio communication devices which are capable to implement IP transmission. This paper presents the requirements for the HF and VHF radio systems according to the IP protocol requirements. At the beginning basic properties of narrowband HF and VHF waveforms in context of their operational scenarios has been described. Then results of experimental research (implementation of narrowband services — voice and data) has been presented. Finally further research directions with contribution of the authors, in NATO working groups related to the development of NBWF (Narrowband Waveform) for coalition communication has been presented.
The aim of the article was to present selected methods for the production of layered composites in the aspect of the additive in the form of polyester-glass recyclate. The polyester-glass recyclate was obtained from the original composite material from which the ship’s hull was made in Poland in the 1980s. The article presents the technology of processing polyester-glass waste in order to obtain recyclate. The methods of manual lamination, vacuum bag method and vacuum infusion were described successively. The advantages and disadvantages of particular technologies have been presented in terms of the possibility of their use in the production of polyester-glass recycled composites. From the described and verified technologies, the vacuum bag method can be the most advantageous for composites with recyclate.
This article is an attempt to interest the subjects associated with maritime technology — in the possibilities of increasing the safety of Polish Navy ships (or civilian ships), which may be threatened by attacks of maneuvering missiles and drones moving at low altitude at high speed. The concept proposed by the team was initially verified in simulation tests and the obtained results of these studies indicate that the automated missile self-defence system based on guided and unguided missiles with caliber 40 mm and 70 mm, can be an effective means of self-defence (even the smallest vessels). Small dimensions and mass as well as simplicity of use and reliability of this weapon system allow to believe that 40 mm MLRS1 could also be used by special forces of Polish Navy in offensive operations (destruction of lightly armoured objects of surface or ground, vehicles, force, putting smoke screens, mine mines) to 2000 m. For that reason, the system is referred to by the team of implementers as ‘pocket rocket artillery’.
The article presents the analysis of the threats to ships of the Polish Navy resulting from the implementation systems of active neutralization for missiles of MANPADS (e.g. Grom, Igla, Mistral) to the armed forces of the Russian Federation.
The paper describes the most popular sea anti-aircraft missile sets based on MANPADS missiles and the capabilities of Russian multi-sensor systems for protection of Vitebsk class helicopters and aircraft (President-S). The article contains conclusions from the analysis of the capabilities of weapon systems and active disruption systems in the confrontation of a present ship with a modern combat helicopter and proposals for solving this problem by means of the diversification of missile of anti-aircraft systems.
Increasing security in Polish maritime areas is not only a priority for maritime administration, but all users of this zone. The article proves the general assumptions of the implementation of the National Maritime Safety System as well and the method of implementation of its individual elements. Detailed system information was included PHI-CS and Information Exchange System and Sailing Safety. An attempt was made to investigate the scope of modernization of the System of Information and Navigation Safety System. The article describes elements: the national Safe Sea Net system, rules of passenger registration, databases, ICT connections.