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1
Content available remote An investigation on the effective mass of the robot: dependence on the end-effector position
Sharkawy Abdel-Nasser
Engineering Transactions
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2021
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Vol. 69, iss. 3
293--313
EN
In this paper, the mathematical analysis of the robot effective mass is presented. The calculation of this effective mass and its ellipsoid are included. The relationship between the robot effective mass and the external force (collision) affecting the robot end-effector is investigated. The effective mass is analyzed using different robot configurations and different end-effector positions. This analysis is conducted using 2-DOF and 3-DOF planar robots and executed using MATLAB. The results from this analysis prove that the robot effective mass depends on the its configurations and end-effector position. Effective mass can thus be considered as one of the criteria in optimizing robot kinematics and configuration.
2
Content available Kidney Segmentation in CT Data Using Hybrid Level-Set Method with Ellipsoidal Shape Constraints
Skalski A., Heryan K., Jakubowski J., Drewniak T.
Metrology and Measurement Systems
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2017
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Vol. 24, nr 1
101--112
EN
With development of medical diagnostic and imaging techniques the sparing surgeries are facilitated. Renal cancer is one of examples. In order to minimize the amount of healthy kidney removed during the treatment procedure, it is essential to design a system that provides three-dimensional visualization prior to the surgery. The information about location of crucial structures (e.g. kidney, renal ureter and arteries) and their mutual spatial arrangement should be delivered to the operator. The introduction of such a system meets both the requirements and expectations of oncological surgeons. In this paper, we present one of the most important steps towards building such a system: a new approach to kidney segmentation from Computed Tomography data. The segmentation is based on the Active Contour Method using the Level Set (LS) framework. During the segmentation process the energy functional describing an image is the subject to minimize. The functional proposed in this paper consists of four terms. In contrast to the original approach containing solely the region and boundary terms, the ellipsoidal shape constraint was also introduced. This additional limitation imposed on evolution of the function prevents from leakage to undesired regions. The proposed methodology was tested on 10 Computed Tomography scans from patients diagnosed with renal cancer. The database contained the results of studies performed in several medical centers and on different devices. The average effectiveness of the proposed solution regarding the Dice Coefficient and average Hausdorff distance was equal to 0.862 and 2.37 mm, respectively. Both the qualitative and quantitative evaluations confirm effectiveness of the proposed solution.
3
Content available The Added Mass Coefficient computation of sphere, ellipsoid and marine propellers using Boundary Element Method
Ghassemi H., Yari E. M.
Polish Maritime Research
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2011
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nr 1
17-26
EN
Added mass is an important and effective dynamic coefficient in accelerating, non uniform motion as a result of fluid accelerating around a body. It plays an important role, especially in vessel roll motion, control parameters as well as in analyzing the local and global vibration of a vessel and its parts like propellers and rudders. In this article, calculating the Added Mass Coefficient has been examined for a sphere, ellipsoid, marine propeller and hydrofoil; using numerical Boundary Element Method. Since an Ellipsoid and a sphere have simple geometric shapes and the Analytical values of their added mass coefficients are available, so that the results of added mass matrix are obtained and evaluated, using the boundary element method. Then the added mass matrix is computed in a given geometrical and flow specifications for a specific propeller and its results are studied versus experimental results, which it’s current numerical data In comparison with other numerical methods has a good conformity with experimental results. The most important advantage of the method in determining the added mass matrix coefficients for the surface and underwater vessels and the marine propellers is extracting all the added mass coefficients with very good Accuracy, while in other numerical methods it is impossible to extract all the coefficients with the Desired Accuracy.
4
Content available remote Rozkład ładunku na przewodzącej elipsoidzie
Gładkow J.
Przegląd Elektrotechniczny
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2005
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R. 81, nr 1
47-51
PL
Przedstawiono sposób uzyskania dokładnego wzoru na rozkład gęstości powierzchniowej ładunku na różnoosiowej elipsoidzie przewodzącej.
EN
Method calculating of distribution surface charge density on the conducting ellipsoid.
5
Content available remote Theoretical analysis of selected working parameters of fragmentizers from smooth rollers
Mieszkalski L.
Technical Sciences / University of Warmia and Mazury in Olsztyn
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2002
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nr 5
31-40
EN
The paper presents a theoretical analysis of such parameters as minimum - ray of rollers, angle of grasp and length of crumbling zone for fragmentizers with smooth rollers. The cooperation betweem rollers and a small part of crumbled material of spherical and elliptical shapes was examined. An increase in minimum ray of rollers enabling the compression of the material, angle of grasp, length of crumbling zone follows when the supplementary ray of crumbled material increases and the width of working crevice between rollers decreases.
PL
W pracy przedstawiono analizę teoretyczną takich parametrów rozdrabniaczy z walcami gładkimi, jak: minimalny promień walców, kąt chwytu oraz długość strefy rozdrabniania. Rozpatrzono współpracę z walcami cząstki rozdrabnianego materiału o kształtach kulistych i elipsoidalnych. Wzrost minimalnego promienia walców zapewniający zakleszczanie nadawy, kąta chwytu, długości strefy rozdrabniania następuje, gdy wzrasta promień zastępczy rozdrabnianego materiału i maleje szerokość szczeliny roboczej między walcami.
6
Content available remote Mathematical model of seed motion in the process of husking in a hulling machine equipped with a rotating grinding wheel positioned veritically
Mieszkalski L., Lewandowski R.
Technical Sciences / University of Warmia and Mazury in Olsztyn
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2000
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nr 3
65-76
EN
The paper presents a mathematical model which allows to determine the parameters of seed motion in the working space of a hulling machine equipped with a grinding wheel positioned vertically. The model was formulated on the basis of the laws of solid body motion. The dependence between the velocity of seed collision with the head and casing of a hulling machine and the angular velocity of the grinding wheel was described. The distance covered by a falling seed between rebounds against the head and casing of a hulling machine was also determined. Symbols are in the text.
PL
Na podstawie praw o ruchu ciała stałego opracowano model matematyczny, opisujący parametry ruchu nasion w przestrzeni roboczej obłuskiwacza z pionową głowicą ściernicową. Wyznaczono prędkości zderzeń nasion z głowicą i obudową obłuskiwacza w zależności od prędkości kątowej głowicy oraz odległości, o jaką opadnie nasiono między kolejnymi odbiciami od głowicy i obudowy obłuskiwacza. Wykaz oznaczeń znajduje się w tekście.
7
Content available remote Osnowy a układy
Kadaj R.
Geodeta : magazyn geoinformacyjny
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2000
|
nr 12
28--32
8
Content available remote Elipsoidy a układy
Kadaj R.
Geodeta : magazyn geoinformacyjny
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2000
|
nr 11
15--19
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