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PL
Jednym ze sposobów korygowania rozkładu temperatury powierzchni nagrzewanego wsadu o złożonych kształtach jest zmiana częstotliwości źródła zasilania. Metoda ta umożliwia uzyskanie dużej równomierności nagrzewanie powierzchni wsadów wklęsło-wypukłych, jak np. koła zębate. Prowadzi ona do relatywnie prostej konstrukcji wzbudnika, np. wzbudnika cylindrycznego. W pracy, wykorzystując symulacje 3D pola elektromagnetycznego i sprzężonych pól elektromagnetycznego i temperatury, przeanalizowano powyższe zjawisko dla przypadku nagrzewania matrycy do zaginarki.
EN
One way to adjust the surface temperature distribution of induction heating charge of complex shapes is to change the frequency of the power supply. This method allows a very high uniformity of heating of the surface of the convex-concave charges such as gear wheels. In this paper, using the 3D simulation the electromagnetic and temperature fields were analyzed induction heating of the matrix to flanging.
EN
Non-stationary optimization of randomly changing environments is a subject of unfading interest.In this paper we study application of multipopulation evolutionary algorithm to this problem. Presented algorithm works with a set of sub-populations managed by the mechanism of exclusion coming from the multiswarm version of particle swarm approach. The results show significant improvement of the efficiency of the new algorithm in comparison with a single population approach.
EN
This paper presents the results of research of influence of degree and number of polynomial terms of railway transition curves (TCs) on their dynamical properties. The research performed for needs of this work are planned numeric tests. The search for the proper shape means the evaluation of the curve properties based on chosen dynamical quantity and generation of such shape with the use of mathematically understood optimisation methods. For the needs of this work advanced vehicle model, dynamical track-vehicle and vehicle-passenger interactions as well as optimisation methods were exploited. The subject of the analysis are odd degree polynomial transition curves of the 5th, 7th, 9th and 11th degree. For each degree of the polynomial a range of acceptable number of polynomial terms was determined. One dynamical quantity - minimum of integral of vehicle body lateral acceleration - being the results of simulation of railway vehicle advanced model is exploited in the determination of quality function (QF).
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The predicted annual growth of energy consumption in ICT by 4% towards 2020, despite improvements and efficiency gains in technology, is challenging our ability to claim that ICT is providing overall gains in energy efficiency and Carbon Imprint as computers and networks are increasingly used in all sectors of activity. Thus we must find means to limit this increase and preserve quality of service (QoS) in computer systems and networks. Since the energy consumed in ICT is related to system load, ]this paper discusses the choice of system load that offers the best trade-off between energy consumption and QoS.We use both simple queueing models and measurements to develop and illustrate the results. A discussion is also provided regarding future research directions.
EN
The paper has been written within the European EUREKA Project E!2772, initiated and completed at the Faculty of Ocean Engineering & Ship Technology, Gdansk University of Technology in the years 2001-2003. A problem has been solved concerning mathematical optimisation of a fleet of multipurpose sea-river vessels for European short-shipping reguIlar lines, in the area of The North and Baltic Seas, on the level of marine transportation , task, by the non-linear programming methods with constraints. A method is proposed which enables existing criteria of stability to be included as constraints in the optimisation model of a jleet. In the numerical examples, three typical criteria of intact stabiliry: by IMO, PRS, and HSMB have been selected to demonstrate a post-optimisation feasibility analysis of principal parameters of ships.
EN
The article concerns the issues of the scope of optimization of the gas turbine jet engine. These issues include limiting the weight and number of engine parts. One way to reduce the weight and number of components, including the compressor assembly, is to use the BLISK's replacement construction. The replacement construction should meet the strength requirement and the vibration spectrum as well. The paper presents a comparative analysis of the influence of rotational speed on the characters and the vibration frequency of the single rotor stage of the high pressure compressor. The analysis was carried out for two different design solutions of the blade-disk connection: the classical and integral. The comparative analysis focused on three important from the point of view of operation, the engine operating ranges: work on the ground (idle) and work during take-off and climb the aircraft.
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Content available Simulation in factory optimisation
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EN
Many manufacturing systems must operate under resource constraints. Simulation can help to improve the operation of such manufacturing systems. This paper presents a practical approach how to conduct a simulation project. A Flexible Manufacturing System (FMS) was chosen for the simulation. The targets for FMS improvement were given. A set of measures was proposed to meet the given targets. Design of Experiments (DoE) was used to minimise the number of simulation experiments. There were simulated and evaluated various measures and control strategies and their influence on the FMS characteristics. Rough cost analysis of each simulated variant was done. Future research targets are presented.
EN
This paper addresses the problem of ventral hernia repair. The main goals are to find an optimal surgical mesh for hernia repair and to define its optimal orientation in the abdominal wall to minimise the maximum force at the tissue-implant juncture. The optimal mesh is chosen from a set of orthotropic meshes with different stiffness ratios for typical hernia placement in the abdominal area. The implant is subjected to an anisotropic displacement field, different for the selected hernia placements. The assumed displacement fields correspond to regular human activity. Proper implantation of the mesh may determine the success of hernia repair and/or the postoperative comfort of patients. The proposed solution is based on FEM simulations of different surgical meshes behaviour. In typical hernia placements, the optimal orientation of the stiffer direction of the implant is perpendicular to the spine. However, the presented results show some cases that an oblique direction may be the optimum one.
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Content available remote Towards the evolution of neural networks
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EN
Evolutionary artificial neural networks have gradually evolved as a new field at the junction of artificial neural networks and evolutionary algorithms. Rapid growth of both fields could be observed in the last few years. However, limitations i neural networks technoques can diminish the potential of neural networks. Some of these limitations can be treated as optimisation problems. As a consequence, evolutionary algorithms can be used to overcome these deficiencies of traditional neural network methods. The primary objective of this paper is to highlight the most important factures of evolutionary algorithms and the way they can be used to increase the efficiency of neural networks techniques. It is assumed that the reader is familiar with the basic concepts of neural networks.
EN
Advancing climate change, tense world markets, and political pressure steadily increase the demand for resource-optimized production solutions. Herby, the positioning of the raw material in the machine tool is an important factor that has received little attention. Traditionally, this is done centrally on the machine table, which leads to locally increased wear of the feed axis. Furthermore, positioning directly influences energy consumption during machining. Consequently, the longest possible component utilization through optimum wear and energy optimization creates a direct conflict of objectives. To solve this conflict, this paper presents an automated approach for software-defined workpiece positioning and NC-Code optimization regarding the axis-specific energy consumption and the spindle condition of ball screws. An approach for mapping the energy consumption and the directly measured spindle condition is presented. Both represent input variables of the cost function. Approaches for the optimization of the position as well as for the practical implementation are proposed.
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Content available remote Active noise control - a review of control-related problems
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EN
Active noise control is a research area, where both acoustic and control related problems influence success of applications. The aim of the paper is to address the control aspects. After introducing active noise control in general, the fundamental state of the art is presented. The possible control techniques are discussed. Premises for the choice of feedforward, feedback and combined architectures are summarised. Single-channel and multi-channel systems are confronted. Benefits and drawbacks of continuous-time and discrete-time approaches are emphasised. Fixed-parameter and adaptive control systems are referenced. General control system requirements are formulated. Fundamental performance limitations are explained. Various control problem formulations including cost functions and constraints are presented for an exemplary structure.
EN
Grinding of biological materials is an energy-consuming process. During grain decohesion, complex strain state occurs induced by compressing, twisting, bending, tearing, cracking, grinding or shearing. The work attempts to find structural solutions of the grinding and process control system enabling to increase rice grinding functionality: efficiency, energy-saving and regularity. The practical aim was to develop the methodology for innovative research on grain grinding which supports development of grinders. Based on theoretical discussions and earlier scientific research, it can be concluded that it is possible to obtain optimal quality of material being ground and satisfactory functionality of the rice grain grinding process within a permissible range of values of the multi-disc grinder structural features. The exceeding of these values will result in the worsening of the process effectiveness and the quality of a grinding product. Finding relations between functionality, operation regularity, selected movement and energy related characteristics of the grinding process and structural features of the biomaterial grinding unit justifies the need for carrying out an analysis, studies and experiments with quasi-shearing in order to determine the indexes of the research object model variables.
EN
In the paper an algorithm and computer software for the optimisation of error actuated control systems containing an electromagnetic linear actuator is presented. The software consists of two main parts: (a) optimisation solver and (b) numerical model of the actuator. For the optimisation the genetic algorithm (GA) has been used. The field-circuit discrete mathematical model of the actuator has been employed. The model includes: (a) the equation of a transient electromagnetic field, (b) equations which describe electric circuit of the actuator, (c) the equation of mechanical motion and (d) the equation describing the feedback - including the proportional-plus-integral-plus-derivative (PID) controller.
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An algebraic approach to performance optimisation of collision-free traffic route systems is presented. The proposed models take into account traffic conditions in a wide area and react to the dynamic nature of the traffic flow. The adjustment of traffic-signal timings to minimise the total travel time through a city is considered. The approach is based on the (max, +) and (min, +) algebras which provide a framework to build an executable performance-oriented model for sequential and repetitive processes like a set of signalised intersections coordinating the traffic access to the routes through a sequence of signal timings. The concept of a quasi-rendez-vous synchronisation mechanism of processes is introduced. A computer example is provided in the final part of the paper to iIlustrate the effectiveness of the approach.
EN
This paper presents the results of research of influence of degree and number of polynomial terms of railway transition curves (TCs) on their dynamical properties. The research performed for needs of this work are planned numeric tests. The search for the proper shape means the evaluation of the curve properties based on chosen dynamical quantity and generation of such shape with the use of mathematically understood optimisation methods. For the needs of this work advanced vehicle model, dynamical track-vehicle and vehicle-passenger interactions as well as optimisation methods were exploited. The subject of the analysis are odd degree polynomial transition curves of the 5th, 7th, 9th and 11th degree. For each degree of the polynomial a range of acceptable number of polynomial terms was determined. One dynamical quantity - minimum of integral of vehicle body lateral acceleration - being the results of simulation of railway vehicle advanced model is exploited in the determination of quality function (QF).
EN
We optimise the speed gears in a tractor transmission with KISSsoft software under three constraints: input power torque, transmission system volume and the gear ratio for each speed. This study aimed to optimise the module, face width, gear quality, centre distance, number of teeth, helix angle, addendum modification coefficient and pressure angle for each speed while considering the above constraints based on an optimisation chart. Tooth bending stress, tooth contact stress, contact ratio and specific sliding were considered during optimisation. Additionally, the effects of changes in a module on the gear profiles, overlap ratio, number of teeth and weight of the gear pair were examined. Strength calculations of gear pairs that were optimised and defined for all geometric parameters with KISSsoft were calculated with the mathematical model described in ISO 6336, and results were then compared. Finally, backlash was minimised for all gear pairs as defined with geometric parameters, and all dimensions and tolerances were determined for gear inspection after manufacturing. A concept design was also presented. We conclude that both the KISSsoft results and mathematical model results are within the range of the target value.
EN
An application of nonlinear optimisation methods to select some parameters of a passenger car steering system is presented. A simplified planar model of the system as well as spatial multibody models are developed. The simplified model is used in the optimisation task, ensuring minimisation of vibrations of the steering wheel. The optimisation task is solved in two stages. The first one allow us to obtain optimal geometry of the system. In the second stage, nonlinear characteristics of some elements are obtained. The correctness of optimisation results is verified by the application of a more sophisticated spatial model. An own simulation programme has been worked out. It allowed us to perform dynamic analysis of the steering kickback using both simplified and complex structural models as well as to execute a built-in optimisation module. Asymmetric input forces applied to the wheel centre have been used in the computer simulations. The excitations analysed are typical for a car moving over an obstacle. The work presented concentrates on the steering kickback phenomena, which may strongly influence discomfort perceived by the car driver.
PL
W pracy przedstawiono zastosowanie metod optymalizacji do doboru pewnych parametrów układu kierowniczego samochodu osobowego. Przedstawiono zarówno uproszczony, płaski model układu, jak również jego wersję przestrzenną. Model uproszczony wykorzystano w zadaniach optymalizacji, których celem jest minimalizacja drgań przenoszonych na koło kierownicy w wyniku jazdy po nierównej nawierzchni. Zadanie optymalizacji jest rozwiązane w dwóch etapach. W pierszym poszukiwano optymalnej geometrii układu. Nieliniowe charakterystyki układu są znajdywane w drugim etapie. Wyniki optymalizacji zostały następnie zweryfikowane w złożonym modelu układu. Własne oprogramowanie pozwala na przeprowadzanie analiz z zastosowaniem obu modeli oraz dokonywania obliczeń optymalizacyjnych. Analizowano wpływ sił dynamicznych chrakterystycznych dla przejazdu przez przeszkodę kołami jednej strony pojazdu. Wyniki obliczeń koncentrują się na drganiach typu kickback, które są jednym z czynników znacznie wpływających na dyskomfort kierowcy.
EN
This paper presents the classic approach to minimum drag shape body problem, moving at hypersonic speeds, leading to famous power law shapes with value of the exponent of 3 4. Twoand three-dimensional cases are considered. Furthermore, an exact pseudo solution is given and its uselessness is discussed. Two new solutions are introduced, namely an approximate solution due to form of the functional and solution by means of optimisation of a Bézier curve. The former transforms the variational problem to the classic problem of function optimisation by assuming certain class of functions, whereas the latter by means of discretised functional.
EN
The work is concerned with the optimal control and correction of a three-axis gyroscopic platform fixed on board of a flying object. The deviations from the predetermined motion are minimized by means of a method of programmed control, an algorithm of the optimal correction control, and selection of optimal parameters for the gyroscopic platform.
PL
W pracy przedstawione jest sterowanie optymalne i korekcja trzyosiowej platformy giroskopowej, umieszczonej na pokładzie obiektu latającego. Odchylenia od ruchu zadanego są minimalizowane za pomocą sterowania programowego, algorytmu optymalnego sterowania korekcyjnego oraz wyboru optymalnych parametrów platformy giroskopowej.
EN
Some proposition of mathematical logic application for optimization of logistic nets describing motor transport has been presented in this paper. Some algorithm for optimization steps has been proposed in the article. In presented example has been elaborated some optimization of logistic net for motor transport. The optimized logistics network for motor transport significantly improves reliability and contributes to the economical use of the vehicle.
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