• Title/Summary/Keyword: engineering optimization

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The Prediction of Lower Flash Points by Optimization Method

  • Ha, Dong-Myeong;Lee, Sung-Jin
    • International Journal of Safety
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    • v.8 no.2
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    • pp.15-19
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    • 2009
  • The flash point is the most widely used flammability property for the evaluation of the flammability hazard of combustible liquid mixtures. In this paper, the reported flash points for the the binary systems, ethylbenzene+n-butanol and ethylbenzene+n-hexanol were correlated by the optimization method. The optimization method based on the van Laar and Wilson equations were compared with the Raoult's law. The calculated values based on the optimization method were found to be better than those based on the Raoult's law.

Comparative Study of Approximate Optimization Techniques in CAE-Based Structural Design (구조 최적설계를 위한 다양한 근사 최적화기법의 적용 및 비교에 관한 연구)

  • Song, Chang-Yong;Lee, Jong-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.11
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    • pp.1603-1611
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    • 2010
  • The comparative study of regression-model-based approximate optimization techniques used in the strength design of an automotive knuckle component that will be under bump and brake loading conditions is carried out. The design problem is formulated such that the cross-sectional sizing variables are determined by minimizing the weight of the knuckle component that is subjected to stresses, deformations, and vibration frequency constraints. The techniques used in the comparative study are sequential approximate optimization (SAO), sequential two-point diagonal quadratic approximate optimization (STDQAO), and approximate optimization based on enhanced moving least squares method (MLSM), such as CF (constraint feasible)-MLSM and Post-MLSM. Commercial process integration and design optimization (PIDO) tools are utilized for the application of SAO and STDQAO. The enhanced MLSM-based approximate optimization techniques are newly developed to ensure constraint feasibility. The results of the approximate optimization techniques are compared with those of actual non-approximate optimization to evaluate their numerical performances.

Modified complex mode superposition design response spectrum method and parameters optimization for linear seismic base-isolation structures

  • Huang, Dong-Mei;Ren, Wei-Xin;Mao, Yun
    • Earthquakes and Structures
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    • v.4 no.4
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    • pp.341-363
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    • 2013
  • Earthquake response calculation, parametric analysis and seismic parameter optimization of base-isolated structures are some critical issues for seismic design of base-isolated structures. To calculate the earthquake responses for such non-symmetric and non-classical damping linear systems and to implement the earthquake resistant design codes, a modified complex mode superposition design response spectrum method is put forward. Furthermore, to do parameter optimization for base-isolation structures, a graphical approach is proposed by analyzing the relationship between the base shear ratio of a seismic base-isolation floor to non-seismic base-isolation one and frequency ratio-damping ratio, as well as the relationship between the seismic base-isolation floor displacement and frequency ratio-damping ratio. In addition, the influences of mode number and site classification on the seismic base-isolation structure and corresponding optimum parameters are investigated. It is demonstrated that the modified complex mode superposition design response spectrum method is more precise and more convenient to engineering applications for utilizing the damping reduction factors and the design response spectrum, and the proposed graphical approach for parameter optimization of seismic base-isolation structures is compendious and feasible.

Arrangement Template Model for the Arrangement Optimization of Compartments and Equipment of a Submarine (잠수함의 구획 및 장비 배치 최적화를 위한 배치 템플릿 모델)

  • Kim, Ki-Su;Roh, Myung-Il;Kim, Sung-Yong;Ahn, Jin-Woo
    • Korean Journal of Computational Design and Engineering
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    • v.21 no.1
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    • pp.51-60
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    • 2016
  • The arrangement design of a submarine has been performed based on data of parent ships and experts' experiences. To support such a task, it is necessary to accumulate and use systematically the data, and to optimize the task. The expert system for the first issue and the optimization method for the latter issue can be used. At this time, a suitable data structure to share the data on the arrangement design of the submarine should be used. In this study, the data structure named an arrangement template model (ATM) is proposed. To check the applicability of the ATM, a prototype program which consists of the expert system and the optimization method is developed. Finally, the developed program is applied to a small submarine of US Navy. As a result, it is confirmed that the ATM can be used to share the data between the expert system and the optimization method.

Response surface methodology based multi-objective optimization of tuned mass damper for jacket supported offshore wind turbine

  • Rahman, Mohammad S.;Islam, Mohammad S.;Do, Jeongyun;Kim, Dookie
    • Structural Engineering and Mechanics
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    • v.63 no.3
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    • pp.303-315
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    • 2017
  • This paper presents a review on getting a Weighted Multi-Objective Optimization (WMO) of Tuned Mass Damper (TMD) parameters based on Response Surface Methodology (RSM) coupled central composite design and Weighted Desirability Function (WDF) to attenuate the earthquake vibration of a jacket supported Offshore Wind Turbine (OWT). To optimize the parameters (stiffness and damping coefficient) of damper, the frequency ratio and damping ratio were considered as a design variable and the top displacement and frequency response were considered as objective functions. The optimization has been carried out under only El Centro earthquake results and after obtained the optimal parameters, more two earthquakes (California and Northridge) has been performed to investigate the performance of optimal damper. The obtained results also compared with the different conventional TMD's designed by Den Hartog's, Sadek et al.'s and Warburton's method. From the results, it was found that the optimal TMD based on RSM shows better response than the conventional damper. It is concluded that the proposed response model offers an efficient approach regarding the TMD optimization.

Short-term Reactive Power Reserve Optimization Based on Trajectory Sensitivity

  • Sun, Quancai;Cheng, Haozhong;Zhang, Jian;Li, Baiqing;Song, Yue
    • Journal of Electrical Engineering and Technology
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    • v.12 no.2
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    • pp.541-548
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    • 2017
  • An increasing concern is paid to short-term voltage stability with the growth of penetration of induction motor loads. Reactive power reserve(RPR) of power system is critical to improve voltage stability. A definition of short-term voltage stability-related RPR(SVRPR) is proposed. Generators vary their contributions to voltage stability with their location and system condition, etc. Voltage support coefficient based on the second-order trace sensitivity method is proposed to evaluate SVRPR's contribution to short-term voltage stability. The evaluation method can account for the generator's reactive support in transient process and the contingency severity. Then an optimization model to improve short-term voltage stability is built. To deal with multiple contingencies, contingency weight taking into account both its probability and severity is proposed. The optimization problem is solved by primal dual interior point method. Testing on IEEE_39 bus system, it is indicated that the method proposed is effective. Short-term voltage stability is improved significantly by the way of SVRPR optimization. Hence, the approach can be used to prevent the happening of voltage collapse during system's contingency.

Multi-objective Optimization of an Injection Mold Cooling Circuit for Uniform Cooling (사출금형의 균일 냉각을 위한 냉각회로의 다중목적함수 최적설계)

  • Park, Chang-Hyun;Park, Jung-Min;Choi, Jae-Hyuk;Rhee, Byung-Ohk;Choi, Dong-Hoon
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.1
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    • pp.124-130
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    • 2012
  • An injection mold cooling circuit for an automotive front bumper was optimally designed in order to simultaneously minimize the average of the standard deviations of the temperature and the difference in mean temperatures of the upper and lower molds for uniform cooling. The temperature distribution for a specified design was evaluated by Moldflow Insight 2010, a commercial injection molding analysis tool. For efficient design, PIAnO (Process Integration, Automation and Optimization), a commercial PIDO tool, was used to integrate and automate injection molding analysis procedure. The weighted-sum method was used to handle the multi-objective optimization problem and PQRSM, a function-based sequential approximate optimizer equipped in PIAnO, to handle numerically noisy responses with respect to the variation of design variables. The optimal average of the standard deviations and difference in mean temperatures were found to be reduced by 9.2% and 56.52%, respectively, compared to the initial ones.

Automated Molding Design Methodology to Optimize Multiple defects in Injection Molded Parts

  • Park, Jong-Cheon;Kim, Byung H.
    • International Journal of Precision Engineering and Manufacturing
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    • v.1 no.1
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    • pp.133-145
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    • 2000
  • Plastic molding designers are frequently faced with optimizing multiple defects in injection molded parts. these defects are usually in conflict with each other, and thus a tradeoff needs to be made reach a final compromised solution. In this study, an automated injection molding design methodology has been developed to optimize multiple defects of injection molded parts. Two features of the proposed methodology are as follows: one is to apply the utility theory to transform the original multiple objective optimization problem into single objective optimization problem with utility as objective function, the other is an implementation of a direct search-based injection molding optimization procedure with automated consideration of process variation. The modified complex method is used as a general optimization tool in this research. The developed methodology was applied to an actual molding design and the results showed that the methodology was useful through the CAE simulation using a commercial injection molding software package. Applied to production, this study will be of immense value to industry in reducing the product development time and enhancing the product quality.

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MULTI-OBJECTIVE OPTIMIZATION OF THE INNER REINFORCEMENT FOR A VEHICLE'S HOOD CONSIDERING STATIC STIFFNESS AND NATURAL FREQUENCY

  • Choi, S.H.;Kim, S.R.;Park, J.Y.;Han, S.Y.
    • International Journal of Automotive Technology
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    • v.8 no.3
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    • pp.337-342
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    • 2007
  • A multi-objective optimization technique was implemented to obtain optimal topologies of the inner reinforcement for a vehicle's hood simultaneously considering the static stiffness of bending and torsion and natural frequency. In addition, a smoothing scheme was used to suppress the checkerboard patterns in the ESO method. Two models with different curvature were chosen in order to investigate the effect of curvature on the static stiffness and natural frequency of the inner reinforcement. A scale factor was employed to properly reflect the effect of each objective function. From several combinations of weighting factors, a Pareto-optimal topology solution was obtained. As the weighting factor for the elastic strain efficiency went from 1 to 0, the optimal topologies transmitted from the optimal topology of a static stiffness problem to that of a natural frequency problem. It was also found that the higher curvature model had a larger static stiffness and natural frequency than the lower curvature model. From the results, it is concluded that the ESO method with a smoothing scheme was effectively applied to topology optimization of the inner reinforcement of a vehicle's hood.

Optimization of particle packing by analytical and computer simulation approaches

  • He, Huan;Stroeven, Piet;Stroeven, Martijn;Sluys, Lambertus Johannes
    • Computers and Concrete
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    • v.9 no.2
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    • pp.119-131
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    • 2012
  • Optimum packing of aggregate is an important aspect of mixture design, since porosity may be reduced and strength improved. It may also cause a reduction in paste content and is thus of economic relevance too. Several mathematic packing models have been developed in the literature for optimization of mixture design. However in this study, numerical simulation will be used as the main tool for this purpose. A basic, simple theoretical model is used for approximate assessment of mixture optimization. Calculation and simulation will start from a bimodal mixture that is based on the mono-sized packing experiences. Tri-modal and multi-sized particle packing will then be discussed to find the optimum mixture. This study will demonstrate that computer simulation is a good alternative for mixture design and optimization when appropriate particle shapes are selected. Although primarily focusing on aggregate, optimization of blends of Portland cement and mineral admixtures could basically be approached in a similar way.