Maritime Academy of Gdynia
Gdynia, Poland
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Centrum Badan Kosmicznych Polskiej Akademii Nauk and Maritime Academy of Gdynia | Date: 2014-10-22

The object of the invention is a spragging mechanism for application in a tube. It is provided with a band and clamping means. The clamping means are arranged within the tube, outside of which the band is provided. The object of the invention is also a system for guiding bore head, provided with an spragging mechanism, head, means transferring the pressing force to the bore head, and also a curled tube fed from the drum into the wellbore. The curled tube (1) constitutes means transferring the pressing force, exerted by the pressing mechanism (2) via a mechanism releasably connected to the curled tube (1). The object of the invention is also a method of drilling a wellbore, wherein a bore head with an drill bit is lowered down the wellbore and pressed against its bottom, simultaneously inserting a tube into to wellbore. For pressing the head (9) with the drill bit (8) a tube (1) curled of strip (T1) drawn from a drum is used, wherein the pressing force is applied to the tube via a mechanism (11, 13, 2) releasably connected thereto.

Barbucha D.,Maritime Academy of Gdynia
Neurocomputing | Year: 2012

Cooperation as a problem-solving strategy is widely used to build methods addressing complex hard optimization problems. It involves a set of highly autonomous programs (agents), each implementing a particular solution method, and a cooperation scheme combining these autonomous programs into a single problem-solving strategy. Possible form of such cooperation may be based, for example, on adaptive memory methods, where partial elements of good solutions are stored and next combined to create new complete solutions. Alternative approach is based on central memory, where complete elite solutions are exchanged among various agents and/or heuristics. Moreover, cooperatively solving a task is often combined with learning mechanism, where agents adapt their behavior to the new states of environment during the process of solving the problem.The main goal of the paper is to evaluate to what extent a mode of cooperation (synchronous or asynchronous) between a number of optimization agents cooperating through sharing a central memory influences the quality of solutions while solving instances of the Vehicle Routing Problem. The investigated search modes are evaluated using a dedicated cooperative multi-agent system allowing for various modes of cooperation and with the reinforcement learning mechanism implemented in it. © 2012 Elsevier B.V.

Czarnowski I.,Maritime Academy of Gdynia
Pattern Recognition | Year: 2010

Distributed learning from data is one of the typical tasks solved by distributed data-mining techniques and is seen as a fundamental computational problem. One of the approaches suitable for distributed learning is to select, by data reduction, relevant local patterns, called also prototypes, from geographically distributed databases. Next, locally selected prototypes can be moved to other sites and merged into the global knowledge model. The paper presents three agent-based population learning algorithms for distributed learning. The proposed algorithms are based on agent collaborations in distributed prototype selection processes and on agent collaborations when the learning global model is created. The basic property of the presented algorithms is that the prototypes are selected by agent-based population learning algorithm from data clusters induced at distributed sites. The main goal of the paper is to empirically compare how the way of inducing such clusters can influence the distributed learning performance. The paper investigates the agent-based population learning algorithms used to solve distributed data reduction and gives a brief discussion of the procedures for clusters initialization. Finally, computational experiment results are shown. © 2010 Elsevier Ltd. All rights reserved.

Czarnowski I.,Maritime Academy of Gdynia
Knowledge and Information Systems | Year: 2012

Instance selection in the supervised machine learning, often referred to as the data reduction, aims at deciding which instances from the training set should be retained for further use during the learning process. Instance selection can result in increased capabilities and generalization properties of the learning model, shorter time of the learning process, or it can help in scaling up to large data sources. The paper proposes a cluster-based instance selection approach with the learning process executed by the team of agents and discusses its four variants. The basic assumption is that instance selection is carried out after the training data have been grouped into clusters. To validate the proposed approach and to investigate the influence of the clustering method used on the quality of the classification, the computational experiment has been carried out. © 2011 The Author(s).

Soszynska J.,Maritime Academy of Gdynia
International Journal of Pressure Vessels and Piping | Year: 2010

The semi-Markov model of the system operation processes is proposed and its selected characteristics are determined. A system composed on multi-state components is considered and its reliability and risk characteristics are found. Next, the joint model of the system operation process and the system multi-state reliability is applied to the reliability and risk evaluation of the port oil pipeline transportation system. The pipeline system is described and its operation process unknown parameters are identified on the basis of real statistical data. The mean values of the pipeline system operation process unconditional sojourn times in particular operation states are found and applied to determining this process transient probabilities in these states. The piping different reliability structures in various its operation states are fixed and their conditional reliability functions on the basis of data coming from experts are approximately determined. Finally, after applying earlier estimated transient probabilities and system conditional reliability functions in particular operation states the unconditional reliability function, the mean values and standard deviations of the pipeline lifetimes in particular reliability states, risk function and the moment when the risk exceeds a critical value are found. © 2010 Elsevier Ltd. All rights reserved.

Kowalski J.,Maritime Academy of Gdynia
Applied Thermal Engineering | Year: 2014

Presented paper shows the results of the laboratory study on the relation between the chosen malfunctions of a fuel pump and the exhaust gas composition of the marine engine. The object of research is a laboratory four-stroke diesel engine, operated at a constant speed. During the research over 50 parameters were measured with technical condition of the engine recognized as "working properly" and with simulated fuel pump malfunctions. Considered malfunctions are: fuel injection timing delay and two sets of fuel leakages in the fuel pump of one engine cylinder. The results of laboratory research confirm that fuel injection timing delay and fuel leakage in the fuel pump cause relatively small changes in thermodynamic parameters of the engine. Changes of absolute values are so small they may be omitted by marine engines operators. The measuring of the exhaust gas composition shows markedly affection with simulated malfunctions of the fuel pump. Engine operation with delayed fuel injection timing in one cylinder indicates CO2 emission increase and NOx emission decreases. CO emission increases only at high the engine loads. Fuel leakage in the fuel pump causes changes in CO emission, the increase of CO2 emission and the decrease of NOx emission. © 2014 Elsevier Ltd. All rights reserved.

Gnacinski P.,Maritime Academy of Gdynia
Energy Conversion and Management | Year: 2014

This work deals with the effect of a lowered voltage quality on the thermal loss of life and load-carrying capacity of marine induction cage machines. Results of experimental investigations and computer calculations are presented for two low power induction motors with different properties. One of them has a comparatively strongly-saturated magnetic circuit and is especially exposed to the risk of overheating under overvoltage. The other machine has a comparatively weakly-saturated magnetic circuit, and is especially sensitive to undervoltage. The induction motor lifetime expectancy is also estimated on the basis of the temperature coefficient of power quality, whose value is proportional to the windings temperature rise in induction motors especially sensitive to various power quality disturbances. The dependence of the temperature coefficient of power quality and permissible loads for induction motors supplied with voltages of lowered quality is proposed. © 2013 Elsevier Ltd. All rights reserved.

Kowalski J.,Maritime Academy of Gdynia
Applied Energy | Year: 2015

This paper presents the concept of a multi-dimensional marine engine diagnostic tool. The dimensions of the tool are diagnostic signals, which form a vector in affine space. The distance of the resulting vector from reference vectors for considered technical states of the engine is the result of diagnosis. Moreover, diagnostic signals, derived from the composition of the exhaust gas, are also considered. The chosen diagnostic signals are the nitric oxide, carbon oxide, carbon dioxide and oxygen contents in the exhaust gas and the temperatures behind all engine cylinders of the marine engine. Analyses were based on laboratory tests of a 4-stroke marine engine. The operation of the proposed diagnostic tool has been partly verified by a passive experiment under sea operation conditions of a main propulsion marine engine. © 2015 Elsevier Ltd.

The method for measuring the own thermal resistance of a magnetic device consists in that the winding resistance, whose thermometric characteristics slope describes the temperature coefficient of copper resistivity changes _(Cu), is measured as a thermally sensitive parameter. The measurement is carried out in at least three stages, including in turn measurements and calculations based on analytical formulae. The measurement of the own thermal resistance of a magnetic device in the form of a choking-coil is carried out in three stages, while the measurement of the own thermal resistance of a magnetic device in the form of a transformer is carried out in five stages. At the first stage of measurement the winding resistance is measured at a low value of the choking-coil current and the core temperature is measured using a radiometric pyrometer. At the second stage measurements are made, in a thermal steady state, of the winding resistance and, with a radiometric pyrometer, the core temperature at a high value of the current. At the third stage the value of the winding thermal resistance and the mutual thermal resistance between the core and the winding are calculated from given formulae. In the case of a transformer, at the fourth stage a sinusoidal signal is applied across the primary winding and the waveforms of the primary winding current and a voltage across a capacitor are measured using an oscilloscope. The core temperature is also measured. At the fifth stage the value of the core thermal resistance is determined based on given formulae. The circuit for measuring own and mutual thermal resistances of a magnetic device comprises voltmeters, ammeters, an oscilloscope, DC voltage sources, double-throw switches, a radiometric pyrometer, a source of sinusoidal signal, resistors and a capacitor.

The invention relates to the method of removing interference, and the circuit for removing interference in the GNSS system. In the circuit according to the invention navigation parameters are determined from at least three receiving channels of which each comprises an antenna and a multi-channel receiving and processing device (4), (5) and (6), respectively. Signals carriers of navigation parameters from the outputs of the receiving and processing devices are routed into the inputs of a navigation processor (7) where they are concurrently and simultaneously analysed and compared, and once it is found that navigation parameters from one of the channels are distorted, this channels is temporarily removed. The antennae of receiving devices are grouped locally in the delineation of a circle proportionally to their quantity, vertically, slightly deflected from the vertical, with the upper edge towards the centre of a circle. The subject of the invention is intended for the construction of safe navigation satellite systems with a particular emphasis on facilities and means of transport air, but also sea and road transport means, both permanent and moving.

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