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1

Analytical Models for Optimal Design of a Trapezoidal Composite Channel Cross-Section

Pourbakhshian Somayyeh, Pouraminian Majid

Civil and Environmental Engineering Reports

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2021

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Vol. 31, no. 1

118--138

EN

In this paper, several analytical models are presented for the optimal design of a trapezoidal composite channel cross-section. The objective function is the cost function per unit length of the channel, which includes the excavation and lining costs. To define the system, design variables including channel depth, channel width, side slopes, freeboard, and roughness coefficients were used. The constraints include Manning’s equation, flow velocity, Froude number, and water surface width. The Simultaneous Perturbation Stochastic Approximation (SPSA) algorithm was used to solve the optimization problem. The results are presented in three parts; in the first part, the optimal values of the design variables and the objective function are presented in different discharges. In the second part, the relationship between cost and design variables in different discharges is presented in the form of conceptual and analytical models and mathematical functions. Finally, in the third part, the changes in the design variables and cost function are presented as a graph based on the discharge variations. Results indicate that the cost increases with increasing water depth, left side slope, equivalent roughness coefficient, and freeboard.

2

The Design of a Cast Suspension Element, Determined by the Pressure Wave

Żuczek R., Maj M., Piekło J., Pysz S.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 3

59--64

EN

Based on the example of the development process of the cast suspension of a special-purpose vehicle the application of the integrated engineering design methodology (ICME – Integrated Computational Materials Engineering) and the development of construction has been presented. Identification of the operating and critical loads, which are guidelines for carrying out the structure strength shaping process, material and technological conversion, are due to the needs and requirements of the suspension system and the purpose and objectives of the special mobile platform. The developed cast suspension element construction includes the use of high-strength AlZnMgCu aluminum alloy. The properties of the used alloy and designed shape allows for the transfer of assumed operating loads in normal exploitation conditions and in the dynamic, critical loads to the susceptibility to damage in the assumed casting areas. For the proposed design, conducted numerical analyzes includes the impact of the shock wave pulse on the occurrence of the destructive stress fields. Based on their distribution, the areas of possible decomposition of the structure of the design element were estimated. The results allowed to devise an element with predicted destructions that allow to absorb a significant part of the impact energy of the shock wave front, which is also the buffer zone for the propagation of destruction for the critical kinematic nodes of the system.

3

Optimal design of RC frames using a modified hybrid PSOGSA algorithm

Chutani S., Singh J.

Archives of Civil Engineering

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2017

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Vol. 63, nr 4

123--134

EN

The present study has been taken up to emphasize the role of the hybridization process for optimizing a given reinforced concrete (RC) frame. Although various primary techniques have been hybrid in the past with varying degree of success, the effect of hybridization of enhanced versions of standard optimization techniques has found little attention. The focus of the current study is to see if it is possible to maintain and carry the positive effects of enhanced versions of two different techniques while using their hybrid algorithms. For this purpose, enhanced versions of standard particle swarm optimization (PSO) and a standard gravitational search algorithm (GSA), were considered for optimizing an RC frame. The enhanced version of PSO involves its democratization by considering all good and bad experiences of the particles, whereas the enhanced version of the GSA is made self-adaptive by considering a specific range for certain parameters, like the gravitational constant and a set of agents with the best fitness values. The optimization process, being iterative in nature, has been coded in C++. The analysis and design procedure is based on the specifications of Indian codes. Two distinct advantages of enhanced versions of standard PSO and GSA, namely, better capability to escape from local optima and a faster convergence rate, have been tested for the hybrid algorithm. The entire formulation for optimal cost design of a frame includes the cost of beams and columns. The variables of each element of structural frame have been considered as continuous and rounded off appropriately to consider practical limitations. An example has also been considered to emphasize the validity of this optimum design procedure.

PL

W niniejszym artykule przedstawiono bardziej realistyczny i optymalny projekt żlbetowych ram konstrukcyjnych (RC) poprzez hybrydyzację ulepszonych wersji standardowej optymalizacji roju cząsteczek (PSO) oraz standardowy algorytm wyszukiwania grawitacyjnego (GSA). Podejście proponowane w niniejszej pracy koncentruje się na hybrydyzacji ulepszonych wersji standardowej optymalizacji roju cząsteczek (PSO) oraz standardowym algorytmie wyszukiwania grawitacyjnego (GSA). PSO została zdemokratyzowana poprzez uwzględnienie wszystkich dobrych i złych doświadczeń w zakresie cząsteczek, podczas gdy GSA został zmieniony na samodostosowujący, uwzględniając określony zakres dla niektórych parametrów, takich jak np. stała grawitacyjna i zestaw czynników o najlepszych wartościach sprawności. Optymalny rozmiar i wzmocnienie elementów zostały określone dzięki zastosowaniu techniki w środowisku komputerowym, w którym cały proces analizy, projektowania i optymalizacji został zakodowany w C++. Procedura analizy i projektowania przebiega zgodnie ze specyfikacjami kodów indyjskich. Okazało się, że zastosowanie samodostosowującego algorytmu wyszukiwania grawitacyjnego wraz z demokratyczną techniką optymalizacji roju cząsteczek zapewnia dwie wyraźne przewagi nad standardową PSO i GSA, a mianowicie lepszą zdolność do ucieczki od lokalnej optymalności i szybszy współczynnik konwergencji. Całe sformułowanie dla optymalnego projektu kosztów ramy obejmuje zarówno koszt belek i słupów. W tym podejściu, zmienne każdego elementu ramy konstrukcyjnej zostały uznane za funkcje ciągłe i zaokrąglone odpowiednio do zastosowania praktycznego znaczenia niniejszego badania. Rozważono kilka przykładów, które podkreślają ważność optymalnej procedury projektowania, a wyniki porównano z wcześniejszymi badaniami, w celu sprawdzenia ich skuteczności i efektywności. Proponowany algorytm pokonuje ograniczenia dwóch indywidualnych algorytmów, biorąc pod uwagę ich hybrydę, a tym samym poprawia ogólną wydajność. Wprowadzono niezbędne zmiany, aby badanie było zgodne z wcześniejszymi badaniami. Porównanie z innymi wcześniej stosowanymi technikami hybrydowymi pokazuje, że czas potrzebny na przeprowadzenie procesu optymalizacji w niniejszym badaniu – z wykorzystaniem techniki MPSOGSA – został znacznie zmniejszony. Ponadto, podczas projektowania ram RC obniżono całkowity koszt za pomocą techniki MPSOGSA. Obniżenie kosztów w obszarze stali odgrywa większą rolę w optymalizacji, w porównaniu do redukcji kosztów w przekroju poprzecznym elementów ramy, co zostało szczegółowo przeanalizowane na przykładzie.

4

Optimal Design of Shells of Uniform Stability Stiffened by Ribs

Foryś P.

Mechanics and Mechanical Engineering

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2013

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Vol. 17, nr 1

37--47

EN

The problem of optimal design of rotationally symmetrical shells of uniform stability stiffened by ribs was discussed in the current paper. The structure was modelled in ANSYS software and solved by FEM method. The formulation of uniform local stability was successfully verified by the linear buckling solution. The optimization tasks were solved numerically using the modified Particle Swarm Optimization algorithm. The critical loading multiplier was increased by determining the optimal shape of the meridian, distribution of a wall thickness in a coat of shell and the placement of ribs inside the shell.

5

Specific power optimal design of permanent magnet synchronous motor using GA

Cvetkovkski G., Petkovska L.

Przegląd Elektrotechniczny

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2010

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R. 86, nr 12

24-27

EN

In the design procedure of the analysed permanent magnet synchronous motor (PMSM) several objectives could be tackled, such as an increased efficiency, reduced total weight of the motor or increased power/weight ratio (specific power). In this paper an optimal design of a PMSM using specific power as objective function is performed. In the design procedure performed on the PM motor, genetic algorithm, as an optimisation tool is used. Comparative analysis of the optimal motor solution and its parameters in relation to the initial model is presented.

PL

W procesie projektowania silników elektrycznych z magnesami trwałymi należy brać pod uwagę: wzrost efektywności, zredukowaną wagę całkowitą oraz wzrost stosunku moc/waga (moc właściwa). W artykule pokazano optymalny projekt takiego silnika, używający masy właściwej jako funkcji celu. W procedurze projektowania wykonanej dla silnika z magnesem trwałym użyto algorytmu genetycznego jako narzędzia optymalizacji. Wykonano analizę porównawczą silnika w rozwiązaniu optymalnym i jego parametrów w stosunku do stanu wyjściowego.

6

Sensor network design for the estimation of spatially distributed processes

Uciński D., Patan M.

International Journal of Applied Mathematics and Computer Science

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2010

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Vol. 20, no 3

459-481

EN

In a typical moving contaminating source identification problem, after some type of biological or chemical contamination has occurred, there is a developing cloud of dangerous or toxic material. In order to detect and localize the contamination source, a sensor network can be used. Up to now, however, approaches aiming at guaranteeing a dense region coverage or satisfactory network connectivity have dominated this line of research and abstracted away from the mathematical description of the physical processes underlying the observed phenomena. The present work aims at bridging this gap and meeting the needs created in the context of the source identification problem. We assume that the paths of the moving sources are unknown, but they are sufficiently smooth to be approximated by combinations of given basis functions. This parametrization makes it possible to reduce the source detection and estimation problem to that of parameter identification. In order to estimate the source and medium parameters, the maximum--ikelihood estimator is used. Based on a scalar measure of performance defined on the Fisher information matrix related to the unknown parameters, which is commonly used in optimum experimental design theory, the problem is formulated as an optimal control one. From a practical point of view, it is desirable to have the computations dynamic data driven, i.e., the current measurements from the mobile sensors must serve as a basis for the update of parameter estimates and these, in turn, can be used to correct the sensor movements. In the proposed research, an attempt will also be made at applying a nonlinear model-predictive-control-like approach to attack this issue.

7

Mobile sensor routing for parameter estimation of distributed systems using the parallel tunneling method

Zięba T., Uciński D.

International Journal of Applied Mathematics and Computer Science

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2008

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Vol. 18, no 3

307-318

EN

The paper deals with the problem of optimal path planning for a sensor network with mutliple mobile nodes, whose measurements are supposed to be primarily used to estimate unknown parameters of a system modelled by a partial differential equation. The adopted framework permits to consider two- or three-dimensional spatial domains and correlated observations. Since the aim is to maximize the accuracy of the estimates, a general functional defined on the relevant Fisher information matrix is used as the design criterion. Central to the approach is the parameterization of the sensor trajectories based on cubic B-splines. The resulting finite-dimensional global optimization problem is then solved using a parallel version of the tunneling algorithm. A numerical example is included to clearly demonstrate the idea presented in the paper.

8

Optimal design of the grounding grid by FEM considering different layered soil models

Habjanic A., Trlep M.

Przegląd Elektrotechniczny

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2007

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R. 83, nr 7-8

112-114

EN

In this paper, we use an optimization technique based on the implementation of the exponent rule of the grounding conductor arrangement and the application of the finite element method (FEM) to obtain the most efficient arrangement of the grounding grid’s conductors, guaranteeing the safety regions on the ground surface defined by the maximum touch voltage. To find out the influence of the soil structure on the optimal design of the grounding grid different soil structure models were analyzed.

PL

W artykule przedstawiono technikę optymalizacyjną, bazującą na implementacji prawa wykładniczego w ustawieniu przewodów uziemiających oraz zastosowaniu MES dla otrzymania najbardziej efektywnego ustawienia siatki uziemiającej, gwarantującego bezpieczeństwo na powierzchni zdefiniowane przez maksymalne napięcie dotykowe. Utworzony model pozwolił zbadać wpływ struktury gleby na parametry siatki uziemiającej.

9

FEM-3D for metrological optimal design and transient analysis of combined instrument transformer

Cundeva-Blajer M., Arsov L.

Przegląd Elektrotechniczny

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2007

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R. 83, nr 7-8

96-99

EN

In the paper the finite element method will be used for the analysis of the electromagnetic field phenomena in the three-dimensional domain of a 20 kV combined current-voltage instrument transformer. The results derived from the original program package FEM-3D will be input data for the further metrological optimal design of the transformer. A prototype of the instrument transformer will be realised and tested in a laboratory. The results from the FEM-3D study will also be a basis for an advanced analysis of the instrument transformer during transient regimes.

PL

W artykule wykorzystano metodę elementów skończonych do analizy pola elektromagnetycznego w trójwymiarowym modelu prądowo-napięciowego transformatora pomiarowego o napięciu 20 kV. Wyniki analizy przeprowadzonej przy użyciu pakietu FEM-3D stanowią punkt wyjścia dla procedury optymalnego projektowania transformatora. Prototyp został wykonany i przetestowany w warunkach laboratoryjnych. Wyniki analizy numerycznej zostały również wykorzystane do analizy transformatora, pracującego w stanie nieustalonym.

10

Development of a height-adjustable manhole

Kim Ch. H., Park J. H.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 14, nr 1-2

21--25

EN

Purpose: It is found that to determine optimal dimension of gear-shaped parts through bending stress formulas and Taguchi orthogonal array table. Design/methodology/approach: Whole parts of real manhole were manufactured experimentally by casting nodular graphite cast iron according to the Korean Standard. It can be used as water supply and drainage, sewage, telecommunication cable, traffic sign, electricity supply, etc. with better performance. Findings: This manhole consists of cover, outer cylinder and inner cylinder. The gear-shaped stairs are extruded on the outer wall of inner cylinder, and on the inner wall of outer cylinder. The outer cylinder has three columns of 4~5 receptacles, and the inner cylinder has three columns of 6~7 protrusions. The inner cylinder shall be slided into the outer cylinder and then be rotated within the outer cylinder in order to lock the protrusions into the receptacles. The stairs on outer cylinder and inner cylinder allow workers to control the height of manhole because the height is controlled by adequate locking them on sidewall in installation or rehabilitation of manholes. It is designed for the perfect lock. Practical implications: Use of this manhole must be drastically economical because it requires only 1-2 workers and simple adjustment of the height comparing with that the existing manholes is required 4-5 workers and reconstruction because conventional should be entirely excavated to reinstall or repair. This entire excavation of a manhole causes too much time-consuming work, waste of resources, and obstruction of traffic. Originality/value: This paper describes an optimal design of manhole, which deals with design elements of manhole which has gear-shaped stairs on the road to adjust its height.

11

Hybrid search for optimum in a small implicitly defined region

Zilinskas A.

Control and Cybernetics

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2004

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Vol. 33, no 4

599-609

EN

We consider optimization problems with a small implicitly denned feasible region, and with an objective function corrupted by irregularities, e.g. small noise added to the function values. Known mathematical programming methods with high convergence rate can not, lie applied to such problems. A hybrid technique is developed combining random search for the feasible region of a considered problem, and evolutionary search for the minimum over the found region. The solution results of two test problems and of a difficult real world problem are presented.

12

Material derivative technique in optimal design

Kwiatkowska A., Krawczyk A., Sikora J.

Journal of Technical Physics

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2002

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Vol. 43, no 4

427-431

EN

The paper deals with the problem of shape design, and the shape has to ensure the assumed distribution of the function. The concept of material (substantial) derivative has been employed in order to solve the problem. The numerical model was based on the Finite Element Analysis. The quoted results show that the method of optimisation is effective for the problem of shape design.