No 1/2000

        The paper presents a comparison of the energy behaviour of two widespread structures (of Load Sensing and Adaptive Secondary Control) of the central feeding systems of hydraulic motors in the case of supplying oil to one motor. The research was made possible due to elaboration of the computer simulation method of energy efficiency of hydrostatic transmissions.

       Both system solutions are shortly described together with presentation of equations of the total efficiency ? of the system, graphs of changes of the speed coefficient ?M and charge coefficient MM of the motor.

       Finally, results and analyses of computer simulations of efficiency of the systems are also described.
(POLISH MARITIME RESEARCH, No 1/2000)

        The paper deals with strength calculations of steel elements under combined static and periodic loadings. Two design criteria, (i) and (ii), are presented which ensure that not only the multiaxial stress does not exceed the ultimate (or yield) strength of the material but also that the combination of multiaxial means stress and multiaxial periodic stress does not lead to fatigue failure in design (i) for an infinite fatigue life and (ii) for a finite fatigue life. It is assumed that the stress components are physically independent of each other and that for each of them the corresponding ?-N curve is given. The load modes and material anisotropy are taken into account.
(POLISH MARITIME RESEARCH, No 1/2000)

        The paper describes the problem of aiding the harbour layout design through computer simulation of ship motion. The key aspect of this support relies on treatment of the ship and the commanding pilot as a stochastic sensor testing the given harbour layout under varying environmental conditions. The role and effectiveness of the ship motion simulation in the harbour design are discussed in reference to other existing harbour design support methods.
The paper presents an example of the simulation experiment which was used for the selection of the harbour layout during planing of the expansion of Port of Callao, Peru. Such example may be used as a pattern for nautical analysis with the application of ship-handling simulation technology. The paper also evaluates the degree of fulfillment of the simulation objectives and points out the areas for further research.
(POLISH MARITIME RESEARCH, No 1/2000)

        In this paper the original method is presented which makes it possible to select a pump arrangement by applying the statistical distribution of real demand for cooling sea water, obtained with taking into account the statistical distributions of sea-water temperature and the total cooling heat flow of power plant during ship operation.
(POLISH MARITIME RESEARCH, No 1/2000)

        The paper continues description of the problems already presented in Polish Maritime Research [1], connected with pollution of the atmosphere by ship engines. In this paper results are described and discussed of further research on the influence of selected control parameters of a high-pressure diesel engine working on heavy fuel oil on its exhaust gas content, carried out at the laboratory of Gdynia Maritime Academy.
(POLISH MARITIME RESEARCH, No 1/2000)

No 2/2000

        The paper presents the problem of tip vortex cavitation inception in the flow around a screw propeller. The most recent experimental and theoretical results concerning mechanisms of tip vortex generation and vortex cavitation inception are reported.
(POLISH MARITIME RESEARCH, No 2/2000)

        In this paper preliminary and exemplary results are presented of voltage analysis on busbars of the main switchboard. Special attention was paid to voltage and its frequency deviation from their nominal values as well as to different voltage waveform distortions. The research contains measurement results of two electrical power systems: of a ro-ro ship and ferry ship. The analysis was carried out off-line on the basis of voltage samples from different states of ship exploitation. The analyzed electrical power systems and measurement devices are also described.
(POLISH MARITIME RESEARCH, No 2/2000)

        This is the second part of a paper presenting the original method which makes it possible to select a pump arrangement by applying the statistical distribution of real demand for cooling sea water, obtained with taking into account the statistical distributions of sea-water temperature and the total cooling heat flow of power plant during ship service.
(POLISH MARITIME RESEARCH, No 2/2000)

        Autonomous simulation of ship movement, i.e. simulation without human factor applied directly to steering, but rather indirectly with the use of expert database or artificial intelligence methods, can be very effective at early stages of the fairway boundary designing and manoeuvre area determining. A verified autonomous model working in fast time is much less time consuming and no expert navigator requiring in comparison to a classic simulation model. This paper presents calculation methods of a distance to fairway boundary and of domain designation used in such model of automatic ship movement. Final algorithm of domain designation is optimized according to time duration and calculation accuracy. The calculated parameters serve as criteria for the next manouuvre decision. An exemplary algorithm of the autonomous simulation model of ship movement in fast (accelerated) time, based on these assumptions is presented. (POLISH MARITIME RESEARCH, No 2/2000)

        This paper contains results of the research on Digital Selective Calling (DSC) carried out in real conditions of sea voyages during the last year of GMDSS implementation. The results make it possible to estimate a degree of DSC system usefulness in achieving its assumed functions within GMDSS.
(POLISH MARITIME RESEARCH, No 2/2000)

        The shiphandling training boat “Kołobrzeg” used during courses for navigators is described and a transformation method is presented of the mathematical model of dynamic and kinematic behaviour of the ferry ship [1] into that of the training boat. Also, a method is described of ship course filtration and reconstruction of turn angular velocity by means of the Extended Kalman’s Filter.
(POLISH MARITIME RESEARCH, No 2/2000)

No 3/2000

        This paper presents an analysis of the work concerning the mathematical descriptions of the energy losses in pumps and hydraulic motors, which are applied in the hydrostatic transmissions. These losses are estimated from the point of view of the possibility to introduce the whole of the hydrostatic drive into the simulation model of energy efficiency. Model of the volumetric losses in the displacement machines with the rotational movement is proposed.
(POLISH MARITIME RESEARCH, No 3/2000)

        A study is presented of mutual coupling of the lateral, torsional and axial vibrations in multi-supported rotors operating in the non-linear range. The object of investigations is a 200 MW turbogenerator founded on seven slide bearings. Presented are the methods of modelling of rotor cracks. These defects were regarded as the reasons of generating the coupled forms of vibrations. The work contains trajectories and vibration spectra of the real objects, as well as the results of tuning the model to the operational data of the objects.
(POLISH MARITIME RESEARCH, No 3/2000)

        In the paper results are presented of vibroacoustic research on balance control of gas turbine rotors and assessment of their permissible operation times. The work is a part of implementation of an integrated diagnostic control system of gas turbines installed on Polish Navy ships fitted with COGAG propulsion systems.
(POLISH MARITIME RESEARCH, No 3/2000)

        More and more ships are presently provided with propulsion systems consisting of two controllable pitch propellers and bow thrusters. Such systems are designed for improving manoeuvring characteristics of the ship in difficult passages, canals or areas of high traffic intensity. However their features are most effectively utilised if an integrated, computeraided control of the whole propulsion system by means of joystick is applied. The ship speed and movement direction, present with the use of joystick, are not always exactly realized, especially if the ship is exposed to wind, wave and possible sea current effects. In such case the joystick software must include a hydrodynamic model of ship’s movement. The paper presents a model of the joystick-effected control and exemplary results of its computer simulation.
(POLISH MARITIME RESEARCH, No 3/2000)

        In the paper a way of forming numerical models of some ship power plant systems is presented, which makes it possible to monitor work of the entire system, control it, simulate failures and analyse phenomena occurring within the entire system. Particular elements of a simulated system are modelled by using theoretical description of physical phenomena occurring in it. Final result of such simulation obtained from a synthesis of basic elements is presented, as an example, for B672 ship systems.
(POLISH MARITIME RESEARCH, No 3/2000)

No 4/2000

        The paper contains results of the design investigations on three types of fast container ships: catamaran, semi-trimaran and monohull whose resistance, seakeeping properties and propulsive characteristics were tested. Influence of some parameters of the ships on their resistance was also considered. Comparison of their characteristics with those of traditional hull forms showed that the new designs appeared superior especially with respect to ship resistance.
(POLISH MARITIME RESEARCH, No 4/2000)

        This paper presents an analysis of the work concerning the mathematical descriptions of the energy losses in pumps and hydraulic motors, which are applied in the hydrostatic transmissions. These losses are estimated from the point of view of the possibility to introduce the whole of the hydrostatic drive into the simulation model of energy efficiency. Model of the mechanical and pressure losses in the displacement machines with the rotational movement is proposed.
(POLISH MARITIME RESEARCH, No 4/2000)

        The paper presents a solution to the maritime target tracking problem based on 2D radar data. The characteristics of ship movements in a cluttered environment imply the application of complex filtering techniques to achieve a high accuracy estimation of motion parameters. An implementation of tracking procedures based on adaptive interactive multiple model (IMM) algorithms is considered to maintain moving-target tracks. A study of the IMM procedure filter is performed and illustrated by a simulated example of maritime target tracking.
(POLISH MARITIME RESEARCH, No 4/2000)

        Paper presents problems of defining ship-induced loans on navigable canals. New safety criteria are proposed for navigation in restricted waters, based on ship-induced reverse current speed and wave height. The new approach is illustrated by example calculations for a modernized part of Szczecin-Świnoujście waterway. The paper presents also more commonly used criterion-speed of propeller stream at the bottom.
(POLISH MARITIME RESEARCH, No 4/2000)

        In the paper a concept is presented of comparing various means of refrigerated cargo sea shipping. Present state of development of this transport branch shows increasing use of the refrigerated containers whose advantages are broadly recognized: standardized cargo lots, very high loading rate, stable storing temperature during the way from producer to receiver. This paper is aimed at assessing also other consequences of increasing use of the containers such as a loss payload volume relative to that of the refrigerated ship holds, as well as an increase of energy consumption per unit net volume in relation to that of the refrigerated ship.
(POLISH MARITIME RESEARCH, No 4/2000)