Wyniki wyszukiwania - BazTech

1

Estimation of hydrodynamic coefficients from results of real ship sea trials

Kim D.

Polish Maritime Research

|

2018

|

nr 4

65--72

EN

This paper suggests an estimation method for ship’s hydrodynamic coefficients, which is based on the system identification method that calculates an optimum value in a mathematical way. For the purpose of modelling existing ships, this study collects real ship sea trial data as benchmarks. Prior to the optimization, a sensitivity analysis is carried out for easy and effective optimization. The simulation results using optimized coefficients agree well with corresponding benchmarks. Following this, with various trim and draught conditions, this study suggests new estimation formulas that concern all trim and draught conditions. Simulation results applying the estimation formulas are satisfactory in regard to a corresponding benchmark, compared to a result obtained by using an existing regression formula.

2

Influence of flame heating parameters on the hardness of hardened C45 steel

Dargacz M., Starosta R.

Journal of KONES

|

2018

|

Vol. 25, No. 1

41--47

EN

In this article, the impact of selected parameters of heating using a gas torch on the hardness of hardened alloy steels C45 was presented. The staff of the ship's engine room sometimes uses flame hardening during casual repairs of the machines weared as a result of operational extortions. The purpose of emergency repairs is to restore the possibility of work of ship machinery and equipment for the duration of the vessel's journey. An acetylene-oxygen torch was used to heat the steel. As the analysed parameters of the technological process, the heating time and the distance between the nozzle and the workpiece were selected. The values of the mentioned parameters have been selected so that the temperature of hardened steel is in the range from 800 to 1250 oC. The following values of the adopted machining parameters were used: the heating time was 60, 85 and 110 seconds, while the distance of the torch nozzle was 10, 20 and 30 mm. After heating, the samples were cooled by immersing in water. The research was based on a randomized orthogonal experiment plan. The purpose of the quantitative assessment of the influence of heating parameters on the hardness of hardened C45 steel, done statistical analysis variance analysis, multiple regression and mathematical optimization by the Tagichi method. Conducted tests and statistical analysis showed a significant effect of selected parameters of flame heating on the hardness of hardened C45 steel. The greatest influence on the hardness of the steel is the distance between the nozzle and the workpiece. The highest value of hardness was obtained using the following parameters of flame hardening: nozzle distance 30 mm, heating time 60 seconds.

3

Catalytic and Purely Catalytic P Systems and P Automata: Control Mechanisms for Obtaining Computational Completeness

Freund R., Oswald M., Păun G.

Fundamenta Informaticae

|

2015

|

Vol. 136, nr 1/2

59--84

EN

The questions whether catalytic P systems with only one catalyst and purely catalytic P systems with only two catalysts can already be computationally complete in the generative case, still are open problems. For accepting P systems or P automata, the situation is even more complicated when we consider sets of vectors of natural numbers and not only sets of natural numbers – the number of catalysts increases with the dimension of the vectors. We here establish computational completeness for catalytic P systems and P automata with only one catalyst as well as for purely catalytic P systems and P automata with only two catalysts in the skin membrane by using specific variants of additional control mechanisms: in P systems and P automata with label selection, we only use rules from one set of a finite number of sets of rules in each computation step; in time-varying P systems and P automata the available sets of rules change periodically with time. The same control mechanisms also allow for computing partial recursive relations or functions of (vectors of) natural numbers when being used in catalytic P systems with one catalyst and purely catalytic P systems with two catalysts. Finally, these variants of P systems can also be used to generate or accept strings and to compute partial relations or functions on strings, and again we obtain computational completeness with only one catalyst in the case of catalytic P systems and two catalysts in the case of purely catalytic P systems.

4

Rotation error modeling and identification for Robot kinematic calibration by circle point method

Santolaria J., Conte J., Pueo M., Javierre C.

Metrology and Measurement Systems

|

2014

|

Vol. 21, nr 1

85--98

EN

Screw axis measurement methods obtain a precise identification of the physical reality of the industrial robots’ geometry. However, these methods are in a clear disadvantage compared to mathematical optimisation processes for kinematical parameters. That’s because mathematical processes obtain kinematical parameters which best reduce the robot errors, despite not necessarily representing the real geometry of the robot. This paper takes the next step at the identification of a robot’s movement from the identification of its real kinematical parameters for the later study of every articulation’s rotation. We then obtain a combination of real kinematic and dynamic parameters which describe the robot’s movement, improving its precision with a physical understanding of the errors.

5

Coalitions of Arguments : An Approach with Constraint Programming

Bistarelli S., Santini F.

Fundamenta Informaticae

|

2013

|

Vol. 124, nr 4

383--401

EN

The aggregation of generic items into coalitions leads to the creation of sets of homogenous entities. In this paper we accomplish this for an input set of arguments, and the result is a partition according to distinct lines of thought, i.e., groups of 'coherent' ideas. We extend Dung's Argumentation Framework (AF) in order to deal with coalitions of arguments. The initial set of arguments is partitioned into not-intersected subsets. All the found coalitions show the same property inherited by Dung, e.g., all the coalitions in the partition are admissible (or conflict-free, complete, stable): they are generated according to Dung's principles. Each of these coalitions can be assigned to a different agent. We use Soft Constraint Programming as a formal approach to model and solve such partitions in weighted AFs: semiring algebraic structures can be used to model different optimization criteria for the obtained coalitions. Moreover, we implement and solve the presented problem with JaCoP, a Java constraint solver, and we test the code over a small-world network.

6

A Tabled Prolog Program for Solving Sokoban

Zhou N.-F., Dovier A.

Fundamenta Informaticae

|

2013

|

Vol. 124, nr 4

561--575

EN

This paper presents our program in B-Prolog submitted to the third ASP solver competition for the Sokoban problem. This program, based on dynamic programming, treats Sokoban as a generalized shortest path problem. It divides a problem into independent subproblems and uses mode-directed tabling to store subproblems and their answers. This program is very simple but quite efficient. Without use of any sophisticated domain knowledge, it easily solves 14 of the 15 instances used in the competition. We show that the approach can be easily applied to other optimization planning problems.

7

Construction of a dynamic model for a transverse flux motor

Kowol M., Kołodziej J.

Prace Instytutu Elektrotechniki

|

2009

|

Z. 240

129-139

EN

The paper presents the simulation results of the modular reluctance motor (Transverse Flux Motor) with an outer rotor in different transient states. The main goal of the analysis was the developing process of a mathematical TFM model with a high level of accordance with real object. The mathematical model was implemented in Matlab/Simulink environment and compared with the filed-circuit model (FLUX3D). Several computer simulations were carried out for different TFM motor operating conditions.

PL

Praca zawiera wyniki badań symulacyjnych stanów dynamicznych silnika reluktancyjnego o budowie modułowej z wirnikiem zewnętrznym ze strumieniem poprzecznym (TFM). Silnik zbudowany jest z trzech modułów oddzielonych od siebie przekładkami dystansowymi, każdy z modułów zawiera 12 zębów oraz jedno uzwojenie (rys. 1). Poszczególne moduły wirnika przesunięte są względem siebie o dziesięć stopni mechanicznych, natomiast moduły stojana są ułożone symetrycznie względem siebie. Do zasilania w/w silnika zastosowano układ półmostkowy typu "H", składający się z sześciu tranzystorów i diod zwrotnych. Zasadniczym celem badań było opracowanie modelu matematycznego silnika TFM zapewniającego dobre odzwierciedlenie zjawisk występujących w tego rodzaju napędach elektrycznych. Model matematyczny zaimplementowano w środowisku Matlab/Simulink, oraz Tolboox PLECS do zamodelowania układu zasilania. Nieliniowość strumienia magnetycznego zależnego od prądu i położenia kątowego uwzględniono stosując w modelu matematycznym funkcję ψ= f ( i,Θ ) (rys. 4a). Podobne podejście zastosowano w przypadku momentu elektromagnetycznego wyznaczając funkcję T = f ( i,Θ ). Funkcje te wyznaczono w na drodze obliczeń polowych zweryfikowanych pomiarowo. Struktura modelu symulacyjnego ma charakter hierarchiczny. Składa się z podsystemów każdego z pasm (rys. 5), układu zasilania i sterowania (rys. 6) oraz z bloku implementacji wielkości mechanicznych (rys. 7). W punkcie 4 zamieszczono wykresy będące porównaniem badań symulacyjnych przy użyciu modelu matematycznego (Matlab/Simulink) oraz obarczonego dużymi nakładami obliczeniowymi modelu polowoobwodowego (FLUX3D). Na rysunku 8 (a-e) przedstawiono jałowy rozruch silnika TFM przy obniżonym napięciu zasilania. Rysunek 9 (a-c) obrazuje rozruch pod obciążeniem dla znamionowej wartości napięcia zasilania. Porównanie modelu matematycznego z modelem polowo-obwodowym pozwala na wyciągnięcie wniosku o zadowalającej dokładności modelu matematycznego. Otrzymano szereg charakterystyk dla różnych warunków pracy silnika TFM w znacznie krótszym czasie niż dla obliczeń polowo-obwodowych. Opracowane narzędzie umożliwi dalsze, bardziej zaawansowane badania optymalizacyjne z wykorzystaniem metod stochastycznych poszukiwania rozwiązań danego problemu.

8

Zagadnienia optymalizacji sterowania pracą wózka w systemie transportowo-magazynowym

Zając P.

Systems : journal of transdisciplinary systems science

|

2007

|

Vol. 12, nr 2

235-246

EN

In the paper the problem of optimization of controlling the work of a larry car in transport-warehouse systems is discussed from the theoretical point of view. The selection, functioning and rational operating of technical assemblies in systems of the so called "intelligent warehouse" is described, according to verification research carried on with the use of appropriate experimental installations at the Faculty of Mechanics of the Wroclaw University of Technology

9

Optymalizacja maszyn a optymalizacja matematyczna

Osiński Z., Wróbel J.

Zeszyty Naukowe Politechniki Białostockiej. Budowa i Eksploatacja Maszyn

|

2001

|

Z. 8

PL

W pracy przedstawiono wybrane problemy dotyczące teorii konstrukcji maszyn. Ważnym elementem tej teorii są zasady konstrukcji. Są to ogólne i szczegółowe zasady konstrukcji. Mogą one być sformułowane w matematyczny sposób. Druga ogólna zasada konstrukcji została sformułowana jako zadanie optymalizacji. Jako szczególny problem optymalizacji rozważono zadanie polioptymalizacji i zadanie dekompozycji dużego zadania optymalizacji. Problemy optymalizacji maszyn sprowadzono w ten sposób do zadania optymalizacji matematycznej.

EN

In the paper the selected problems of the theory of machine design are presented. The important elements of this theory are design principles. General and particular design principles are formulated also in mathematical way. The second general design principle is formulated in mathematical way as a problem of optimization. In the paper also problems of multi-objective optimisation and decomposition of optimisation problems are considered as a particular problems of optimisation. Problems of machine optimisation are reduced to mathematical optimization.