Optimization Methods for Calculating Design Imprecision

1995 ◽  
Author(s):  
William S. Law ◽  
Erik K. Antonsson
Keyword(s):  
Fuzzy Sets ◽  
Design Process ◽  
Optimization Methods ◽  
Experiment Design ◽  
Design Evaluation ◽  
Preliminary Design ◽  
New Methods ◽  
Evaluation Functions ◽  
Incomplete Design ◽  
Alternative Designs

Abstract The preliminary design process is characterized by imprecision: the vagueness of an incomplete design description. The Method of Imprecision uses the mathematics of fuzzy sets to explicitly represent and manipulate imprecise preliminary design information, enabling the designer to explore the space of alternative designs in the context of the designer and customer’s preferences among alternatives. This paper introduces new methods to perform Method of Imprecision calculations for general non-monotonic design evaluation functions that address the practical necessity to minimize the number of function evaluations. These methods utilize optimization and experiment design.

Yacht Design with Computers: New Methods for New Tools

1983 ◽  
Author(s):  
George S. Hazen ◽  
Steve Killing
Keyword(s):  
Design Process ◽  
Preliminary Design ◽  
Original Design ◽  
New Methods ◽  
Design Office ◽  
Final Design ◽  
Cad Cam

From the perspective of the design office, this paper examines the manner in which computers are streamlining and changing the design process for today's sailing yachts. Starting with preliminary design and progressing through the more detailed aspects of final design, the computer's varying roles in the design process are traced with examples drawn from currently implemented programs. In addition to its customary role as a bookkeeper, the computer's remarkable graphics capabilities are highlighted. The authors offer a glimpse of what programs and hardware tomorrow's yacht designer will use as frequently as his curves and battens. The paper covers such subjects as design follow-up, sailing analysis and feedback into the original design process. Since designers are not the only ones to benefit from the computer revolution, the authors have included sections on computer generated sailing aids for the yachtsman and possible CAD/CAM applications for the boatbuilder.

Impact of Secondary Flow on the Accuracy of Simplified Design Methods for Steam Turbine Stages

2012 ◽  
Author(s):  
Jan Schumann ◽  
Ulrich Harbecke ◽  
Daniel Sahnen ◽  
Thomas Polklas ◽  
Peter Jeschke ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Steam Turbine ◽  
Design Process ◽  
Design Method ◽  
Computing Time ◽  
Leading Edge ◽  
Design Methods ◽  
Preliminary Design ◽  
Line Design ◽  
Radial Equilibrium

The subject of the presented paper is the validation of a design method for HP and IP steam turbine stages. Common design processes have been operating with simplified design methods in order to quickly obtain feasible stage designs. Therefore, inaccuracies due to assumptions in the underlying methods have to be accepted. The focus of this work is to quantify the inaccuracy of a simplified design method compared to 3D Computational Fluid Dynamics (CFD) simulations. Short computing time is very convenient in preliminary design; therefore, common design methods work with a large degree of simplification. The origin of the presented analysis is a mean line design process, dealing with repeating stage conditions. Two features of the preliminary design are the stage efficiency, based on loss correlations, and the mechanical strength, obtained by using the beam theory. Due to these simplifications, only a few input parameters are necessary to define the primal stage geometry and hence, the optimal design can easily be found. In addition, by using an implemented law to take the radial equilibrium into account, the appropriate twist of the blading can be defined. However, in comparison to the real radial distribution of flow angles, this method implies inaccuracies, especially in regions of secondary flow. In these regions, twisted blades, developed by using the simplified radial equilibrium, will be exposed to a three-dimensional flow, which is not considered in the design process. The analyzed design cases show that discrepancies at the hub and shroud section do exist, but have minor effects. Even the shroud section, with its thinner leading-edge, is not vulnerable to these unanticipated flow angles.

scholarly journals FUZZY RECURRENT MAPPINGS IN MULTIAGENT SIMULATION OF POPULATION DYNAMICS SYSTEMS

2020 ◽  
pp. 290-297 ◽  
Author(s):  
Dmytro Chumachenko ◽  
Oleksandr Sokolov ◽  
Sergiy Yakovlev
Keyword(s):  
Population Dynamics ◽  
Fuzzy Sets ◽  
Cyber Security ◽  
Fuzzy Model ◽  
Computer Worms ◽  
Multiagent Simulation ◽  
New Methods ◽  
Multi Agent ◽  
Parameter Values ◽  
Unified Description

The article deals with the problems of analyzing multi-agent models of population dynamics. The problems studied are caused by a number of uncertainties associated with variables, boundary conditions, initial states, parameter values, etc. Given problems could be found in tasks associated with cyber security of critical infrastructures (e.g. DDoS attacks, computer worms, etc.). To solve this problem, a linguistic fuzzy model has been developed, which allows describing systems of population dynamics in a more realistic way. Population dynamics is described by a set of rules, each of which involves entry and exit in the form of fuzzy sets or fuzzy functions, which are applied iteratively. The complexity of describing the processes of population dynamics systems, the presence of fuzzification and defuzzification algorithms, and the use of fuzzy sets and linguistic variables make it necessary to develop new methods for analyzing such systems. The approaches proposed in the article to the study of systems of population dynamics make it possible to apply a unified description of processes of different nature in the form of a production set of rules.

scholarly journals FEM Based Preliminary Design Optimization in Case of Large Power Transformers

2019 ◽  
Author(s):  
Tamás Orosz ◽  
David Pánek ◽  
Pavel Karban
Keyword(s):  
Design Optimization ◽  
Design Process ◽  
Optimization Problems ◽  
Optimization Method ◽  
Power Transformers ◽  
Design Stage ◽  
Preliminary Design ◽  
Large Power ◽  
Custom Made ◽  
Transformer Design

Since large power transformers are custom-made, and their design process is a labor-intensive task, their design process is split into different parts. In tendering, the price calculation is based on the preliminary design of the transformer. Due to the complexity of this task, it belongs to the most general branch of discrete, non-linear mathematical optimization problems. Most of the published algorithms are using a copper filling factor based winding model to calculate the main dimensions of the transformer during this first, preliminary design step. Therefore, these cost optimization methods are not considering the detailed winding layout and the conductor dimensions. However, the knowledge of the exact conductor dimensions is essential to calculate the thermal behaviour of the windings and make a more accurate stray loss calculation. The paper presents a novel, evolutionary algorithm-based transformer optimization method which can determine the optimal conductor shape for the windings during this examined preliminary design stage. The accuracy of the presented FEM method was tested on an existing transformer design. Then the results of the proposed optimization method have been compared with a validated transformer design optimization algorithm.

scholarly journals Aero-Structural Optimization of Joined-Wing Aircraft

2017 ◽  
Vol 2017 (4) ◽  
pp. 48-63
Author(s):  
Miłosz Kalinowski
Keyword(s):  
Structural Optimization ◽  
Search Algorithm ◽  
Optimization Methods ◽  
Global Search ◽  
Preliminary Design ◽  
Electric Aircraft ◽  
Modular Algorithm ◽  
Lifting Surfaces ◽  
Joined Wing ◽  
Aircraft Configurations

Abstract Joined-wing aircraft due to its energy characteristics is a suitable configuration for electric aircraft when designed properly. However, because of the specific for this aircraft phenomenons (e.g. static indeterminacy of structure, aerodynamic interference of lifting surfaces) it demands more complicated methods to model its behavior than a traditional aircraft configurations. For these reasons the aero-structural optimization process is proposed for joined-wing aircrafts that is suitable for preliminary design. The process is a global search, modular algorithm based on automatic geometry generator, FEM solver and aerodynamic panel method. The range of aircraft was assumed as an objective function. The algorithm was successfully tested on UAV aircraft. The improvement of 19% of total aircraft range is achieved in comparison to baseline aircraft. Time of evaluation of this global search algorithm is similar to the time characteristic for local optimization methods. It allows to reduce the time and costs of preliminary design of joined-wing.

A Decomposition Method for Concurrent Design of Mixed Discrete/Continuous Systems

1993 ◽  
Author(s):  
Jeffrey M. Ford ◽  
Christina L. Bloebaum
Keyword(s):  
Design Process ◽  
Decomposition Method ◽  
Organizational Design ◽  
Method Development ◽  
Minimum Weight ◽  
Optimization Methods ◽  
Continuous Systems ◽  
Computationally Efficient ◽  
Subspace Optimization ◽  
Design Variables

Abstract Interest in Concurrent Engineering (CE) has increased as industry looks for more efficient means of product design. Design optimization methods that facilitate the CE approach are an important aspect of current research. Among the methods that have been proposed is the Concurrent Subspace Optimization (CSSO) method, which allows the optimization problem to be decomposed into coupled subproblems. These subproblems may correspond to the different disciplines involved in the design process or to participating organizational design or manufacturing groups. The decomposition allows each discipline to apply their own optimization criteria to the problem. While this method may not be as computationally efficient as other methods, it allows the design process to conform to the departmental divisions that already exist in industry. The method development to date has focused on continuous systems only. However, problems that can not be modeled as continuous systems, such as those involving the placement of active controllers in CSI applications, would benefit from a method that allows the use of discrete parameters. The paper presents a decomposition method (based on CSSO) for the optimal design of mixed discrete/continuous systems. The method is applied to the design of a composite plate for minimum weight, with design variables contributed from sizing variables (continuous) and material combinations (discrete).

Framework for metaphor-based spatial configuration design: a case study of Japanese rock gardens

2019 ◽  
Vol 34 (2) ◽  
pp. 223-232
Author(s):  
Yuval Kahlon ◽  
Haruyuki Fujii
Keyword(s):  
Design Process ◽  
Spatial Configuration ◽  
Configuration Design ◽  
Design Phase ◽  
Rock Composition ◽  
Conceptual Design Phase ◽  
Spatial Configurations ◽  
Visual Potential ◽  
Alternative Designs

AbstractMetaphors are powerful tools for design, enabling designers to encapsulate sets of properties and relations as short verbal descriptions. This paper aims to clarify how simple spatial configurations may emerge from concise metaphoric descriptions at the conceptual design phase. To this aim, we propose a framework for a metaphor-based design process. As a basis for the framework, we introduce the concept of “complementary visual potential” – a property which ties the spatial configuration of the objects in the composition with their metaphoric roles. The framework is developed by studying the practice of metaphor-based spatial configuration design in Japanese rock gardens. Accordingly, it is implemented and tested in this context by attempting to generate alternative designs for an existing rock composition in the famous garden of Ryōan-ji. This is followed by a discussion of its possible implications and potential for generalization to other areas of design.

Automated Thermal and Stress Preliminary Analyses Applied to a Turbine Rotor

2016 ◽  
Author(s):  
Maxime Moret ◽  
Alexandre Delecourt ◽  
Hany Moustapha ◽  
Francois Garnier ◽  
Acher-Igal Abenhaim
Keyword(s):  
Design Process ◽  
Turbine Rotor ◽  
Tip Clearance ◽  
Conceptual System ◽  
Preliminary Design ◽  
Design Phase ◽  
Detailed Design ◽  
Turbine Engine ◽  
Cad Models ◽  
The Impact

The use of Multidisciplinary Design Optimization (MDO) techniques at the preliminary design phase (PMDO) of a gas turbine engine allows investing more effort at the pre-detailed phase in order to prevent the selection of an unsatisfactory concept early in the design process. Considering the impact of the turbine tip clearance on an engine’s efficiency, an accurate tool to predict the tip gap is a mandatory step towards the implementation of a full PMDO system for the turbine design. Tip clearance calculation is a good candidate for PMDO technique implementation considering that it implies various analyses conducted on both the rotor and stator. As a first step to the development of such tip clearance calculator satisfying PMDO principles, the present work explores the automation feasibility of the whole analysis phase of a turbine rotor preliminary design process and the potential increase in the accuracy of results and time gains. The proposed conceptual system integrates a thermal boundary conditions automated calculator and interacts with a simplified air system generator and with several conception tools based on parameterized CAD models. Great improvements were found when comparing this work’s analysis results with regular pre-detailed level tools, as they revealed to be close to the one generated by the detailed design tools used as target. Moreover, this design process revealed to be faster than a common preliminary design phase while leading to a reduction of time spent at the detailed design phase. By requiring fewer user inputs, this system decreases the risk of human errors while entirely leaving the important decisions to the designer.

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