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1

Visualization of a lifeboat motion during lowering along ship's side

100%
Kniat A.
Polish Maritime Research
|
2017
|
tom 24
|
nr 4
This paper presents description of a computer program for motion visualization of a lifeboat lowered along ship’s side. The program is a post-processor which reads results of numerical calculations of simulated objects’ motions. The data is used to create scene composed of 3D surfaces to visualize mutual spatial positions of a lifeboat, ship’s side and water waving surface. Since the numerical data contain description of a simulation as a function of time it is possible to screen a static scene showing the simulated objects in an arbitrary instance of time. The program can also reproduce a sequence of scenes in the form of animation and control its speed. The static mode allows to view an arbitrary cross-section of the scene, rotate and enlarge specific details and make the image more realistic by hiding invisible lines or shading. The application of the program is aimed at making it possible to assess and analyze numerical calculation results in advance of their experimental verification
2

The quick measure of a NURBS surface curvature for accurate triangular meshing

100%
Kniat A.
Polish Maritime Research
|
2014
|
tom 21
|
nr 2
NURBS surfaces are the most widely used surfaces for three-dimensional models in CAD/ CAE programs. When a model for FEM calculation is prepared with a CAD program it is inevitable to mesh it finally. There are many algorithms for meshing planar regions. Some of them may be used for meshing surfaces but it is necessary to take the curvature of the surface under consideration to avoid poor quality mesh. The mesh must be denser in the curved regions of the surface. In this paper, instead of analysing a surface curvature, the method to assess how close is a mesh triangle to the surface to which its vertices belong, is presented. The distance between a mesh triangle and a parallel tangent plane through a point on a surface is the measure of the triangle quality. Finding the surface point whose projection is located inside the mesh triangle and which is the tangency point to the plane parallel to this triangle is an optimization problem. Mathematical description of the problem and the algorithm to find its solution are also presented in the paper
3

Optimization of transformation of measurements of ship hull blocks

100%
Kniat A.
Polish Maritime Research
|
2009
|
tom 16
|
nr 4
The paper presents an analysis of measurements taken on ship hull blocks to assess their feasibility for the final stage of assembly in a dry dock or on a slipway. The analysis requires first to check if blocks were manufactured within tolerances assumed in design and then to compare if two neighbouring blocks can be joined to each other. As each block is measured in a different coordinate system it is necessary to make transformations and bring results to a common CAD model without loss of accuracy. An algorithm for optimizing the transformation process to obtain better results, is proposed. The optimization is aimed at minimizing the sum of distances between transformed points and corresponding points in a CAD model. Description of the optimization method and example of its application is also presented. The problem of transformation of measurements or coordinate systems is more general as it can be found, apart from shipbuilding , e.g. in civil engineering, cartography, robot control, pattern recognition, medical imaging
4

On the possible application of wave and hierarchical algorithms in routing pipes in three dimensional space

100%
Kniat A.
Polish Maritime Research
|
1999
|
tom 06
|
nr 4
5

Vertical motions damping model test of a lifeboat lowered onto a flat sea surface

63%
Kniat A., Dymarski P.
Polish Maritime Research
|
2018
|
tom 25
|
nr Special Issue S1
The article presents the experiment’s results of the lifeboat model lowered with an initial speed and then released to fall onto a flat water surface. The purpose of the research is to determine the trajectory of the vertical boat motion and describe it with a mathematical model. This is closely related to determining the damping factor since the vertical motion is damped and the lifeboat gets balanced and stops moving after some time. The procedure of selecting parameters in the mathematical model to adjust to the results of the experiment was described in details. The summary describes the imperfections of the presented damping model and their probable causes
6

Geographic Information System (GIS) tools for aiding development of inland waterways fleet

51%
Zrodowski C., Kniat A., Pyszko R.
Polish Maritime Research
|
2006
|
nr Special Issue S2
The information aiding of planning and operation of inland waterways fleet covers many items among which problems associated with analysis of existing waterways are especially important. Such analyses concern mainly their navigability features (from the point of view of elaboration of design assumptions for floating units) as well as planning land-waterborne transport links. Range of input data for the analyses is very broad hence they can be next used for managing the waterways. This paper presents a concept of forming the GIS data model for the purposes of INCOWATRANS project with taking into consideration the existing data and their possible usage by the administration of waterways and their other users
7

Searching for critical conditions during lifeboat launching - simulations

51%
Dymarski C., Dymarski P., Kniat A.
Polish Maritime Research
|
2017
|
tom 24
|
nr Special Issue S1
The article describes numerical simulations of the process of lifeboat launching at the ship’s side. The research aimed at finding the values of ship motion parameters which appear to be most dangerous for people in the lowered lifeboat due to the generated accelerations. The simplified model of ship hull motion adopted at this research stage bases on a superposition of harmonic motions with given amplitudes and periods in six degrees of freedom. The range of the amplitude of motion for each degree of freedom corresponds approximately to that of possible motion of the PANAMAX type ship on the Baltic sea. In total, 120 960 cases of ship hull motion were examined
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