• Title/Summary/Keyword: hybrid model

Search Result 2,523, Processing Time 0.036 seconds

Assessment of Wind Power Prediction Using Hybrid Method and Comparison with Different Models

  • Eissa, Mohammed;Yu, Jilai;Wang, Songyan;Liu, Peng
    • Journal of Electrical Engineering and Technology
    • /
    • v.13 no.3
    • /
    • pp.1089-1098
    • /
    • 2018
  • This study aims at developing and applying a hybrid model to the wind power prediction (WPP). The hybrid model for a very-short-term WPP (VSTWPP) is achieved through analytical data, multiple linear regressions and least square methods (MLR&LS). The data used in our hybrid model are based on the historical records of wind power from an offshore region. In this model, the WPP is achieved in four steps: 1) transforming historical data into ratios; 2) predicting the wind power using the ratios; 3) predicting rectification ratios by the total wind power; 4) predicting the wind power using the proposed rectification method. The proposed method includes one-step and multi-step predictions. The WPP is tested by applying different models, such as the autoregressive moving average (ARMA), support vector machine (SVM), and artificial neural network (ANN). The results of all these models confirmed the validity of the proposed hybrid model in terms of error as well as its effectiveness. Furthermore, forecasting errors are compared to depict a highly variable WPP, and the correlations between the actual and predicted wind powers are shown. Simulations are carried out to definitely prove the feasibility and excellent performance of the proposed method for the VSTWPP versus that of the SVM, ANN and ARMA models.

Analysis for Combustion Characteristics of Hybrid Rocket Motor (하이브리드 로켓의 연소특성 해석)

  • 김후중;김용모;윤명원
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • 2001.11a
    • /
    • pp.61-67
    • /
    • 2001
  • Hybrid propulsion systems provide many advantages in terms of stable operation and safety. However, classical hybrid rocket motors have lower fuel regression rate and combustion efficiency compared to solid propellant rocket motor. The recent research efforts are focused on the improvement of volume limitation and regression rate in the hybrid rocket engine. The present study has numerically investigated the combustion processes in the hybrid rocket engine. The turbulent combustion is represented by the eddy breakup model and Hiroyasu and Nagle and Strickland-Constable model are used for soot formation and soot oxidation. Radiative heat transfer is modeled by finite volume method. To reduce the uncertainties for convective heat transfer near solid fuel surface having strong blowing effect, the Low Reynolds number k-$\varepsilon$ turbulent model is employed. Based on numerical results, the detailed discussion has been made for the turbulent combustion processes in the vortex hybrid rocket engine.

  • PDF

Data Model for Hybrid Structural Experiments (하이브리드 구조실험을 위한 데이터 모델)

  • Lee, Chang-Ho;Marullo, Thomas;Sause, Richard
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.22 no.5
    • /
    • pp.391-401
    • /
    • 2009
  • The hybrid approach for structural experiments decomposes a structure into independent substructures that can be tested or simulated. The results from the decomposed substructures are combined to predict the behaviors of the entires structure. The hybrid approach is especially useful for the hybrid pseudo-dynamic tests that overcome the limitations of size of a test structure present in a shaking table test. The development of a computer system for the hybrid experiment requires a data model that formally organizes the information involved in the hybrid experiments. This paper provides the data model for representing the information involved in the hybrid experiments, by modifying the classes and attributes for the hybrid experiments in the Lehigh Model that is one of the data models for structural experiments. The data model for the hybrid experiments includes the classes for the physical substructures being tested and the analytical substructures being analyzed, and the simulation coordinator managing the overall experiments. Some objects for classes are implemented as an example to show the links among the classes. The data model presented in this paper can be applied for developing a computer system that helps structural engineers and researchers store, share, and access the information for the hybrid experiments.

Comparison of the CO2 Emissions of Buildings using Input-Output LCA Model and Hybrid LCA Model (산업연관분석법 기반 LCA 모델과 Hybrid LCA 모델의 건축물 이산화탄소 배출량 평가결과 비교)

  • Hong, Taehoon;Ji, Changyoon
    • Korean Journal of Construction Engineering and Management
    • /
    • v.15 no.4
    • /
    • pp.119-127
    • /
    • 2014
  • This study aims to determine whether or not the input output life cycle assessment (I-O LCA) model can be used to assess the carbon dioxide (CO2) emission of buildings in initial planning phase. To ensure this end, this study proposed I-O LCA model which is the simplified LCA model and Hybrid LCA model which is the detailed LCA model, and then assessed and compared the CO2 emission of six case projects (three apartment complexes and three educational facilities) using the two LCA model. The results of the case study showed that the CO2 emissions assessed by the I-O LCA is significantly similar to the CO2 emission assessed by the Hybrid LCA model. The similarity of results from both LCA models was 78.2-86.3% in apartment complexes and 59.9-84.8% in educational facilities. However, the CO2 emissions from I-O LCA model were smaller than the CO2 emissions from Hybrid LCA model in case study. Nevertheless, the case study showed that the I-O LCA model was capable of assessing the CO2 emission of buildings quite appropriately although the I-O LCA model is the simplified LCA model which considers only the construction cost. The I-O LCA model is expected to be a useful tool for assessing the CO2 emission of buildings in initial planning phase.

Analysis of the Fuel Consumption and the Development of the Analysis Model of the Hybrid Tractor (하이브리드 트랙터의 해석모델 개발 및 연료 소비량 분석)

  • Kim, Dongmyung;Kim, Soochul;Lee, Sangheon;Kim, Yongjoo;Jnag, Joosup
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.23 no.3
    • /
    • pp.326-335
    • /
    • 2015
  • In this paper, is a study that analyzed the fuel consumption of hybrid tractor. Testing and analysis in order to evaluate the fuel consumption was performed. Analysis model was developed by using the SimulationX that is a commercial software. Also, map of the analysis model was modeled on the basis of test data. Test was performed using a dynamo device. The engine was tested the fuel consumption in accordance with the conditions on the load and throttle opening. The battery was tested the discharge and charge in accordance with the current amount. We verified the reliability of the analysis model by comparing the analysis results with the rest results. After considering the reliability of each analysis model was extended to the entire hybrid tractor system. To evaluate the efficiency using the analysis model, compared the fuel consumption of general tractor with hybrid tractor in the same load conditions.

Numerical and Experimental Analysis of Spray Atomization Characteristics of a GDI Injector

  • Park, Sung-Wook;Kim, Hyung-Jun;Lee, Chang-Sik
    • Journal of Mechanical Science and Technology
    • /
    • v.17 no.3
    • /
    • pp.449-456
    • /
    • 2003
  • In this study, numerical and experimental analysis on the spray atomization characteristics of a GDI injector is performed. For numerical approach, four hybrid models that are composed of primary and secondary breakup model are considered. Concerning the primary breakup, a conical sheet disintegration model and LISA model are used. The secondary breakup models are made based on the DDB model and RT model. The global spray behavior is also visualized by the shadowgraph technique and local Sauter mean diameter and axial mean velocity are measured by using phase Doppler particle analyzer Based on the comparison of numerical and experimental results, it is shown that good agreement is obtained in terms of spray developing process and spray tip penetration at the all hybrid models. However, the hybrid breakup models show different prediction of accuracy in the cases of local SMD and the spatial distribution of breakup.

Hybrid 신경망을 이용한 산업폐수 공정 모델링

  • Lee, Dae-Seong;Park, Jong-Mun
    • 한국생물공학회:학술대회논문집
    • /
    • 2000.04a
    • /
    • pp.133-136
    • /
    • 2000
  • In recent years, hybrid neural network approaches which combine neural networks and mechanistic models have been gaining considerable interests. These approaches are potentially very efficient to obtain more accurate predictions of process dynamics by combining mechanistic and neural models in such a way that the neural network model properly captures unknown and nonlinear parts of the mechanistic model. In this work, such an approach was applied in the modeling of a full-scale coke wastewater treatment process. First, a simplified mechanistic model was developed based on the Activated Sludge Model No.1 and the specific process knowledge, Then neural network was incorporated with the mechanistic model to compensate the errors between the mechanistic model and the process data. Simulation and actual process data showed that the hybrid modeling approach could predict accurate process dynamics of industrial wastewater treatment plant. The promising results indicated that the hybrid modeling approach could be a useful tool for accurate and cost-effective modeling of biochemical processes.

  • PDF

Hybrid Model-Based Motion Recognition for Smartphone Users

  • Shin, Beomju;Kim, Chulki;Kim, Jae Hun;Lee, Seok;Kee, Changdon;Lee, Taikjin
    • ETRI Journal
    • /
    • v.36 no.6
    • /
    • pp.1016-1022
    • /
    • 2014
  • This paper presents a hybrid model solution for user motion recognition. The use of a single classifier in motion recognition models does not guarantee a high recognition rate. To enhance the motion recognition rate, a hybrid model consisting of decision trees and artificial neural networks is proposed. We define six user motions commonly performed in an indoor environment. To demonstrate the performance of the proposed model, we conduct a real field test with ten subjects (five males and five females). Experimental results show that the proposed model provides a more accurate recognition rate compared to that of other single classifiers.

The Design of Hybrid Filter using 2-nd order Pole-Zero IIR Filters (2차계 Pole-Zero IIR필터를 사용한 Hybrid필터의 설계)

  • 홍의식
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.10 no.1
    • /
    • pp.38-41
    • /
    • 1985
  • The hybrid design which is to take IIR filter of the first stage as a second order pole-zero model and minimize the filter length of the of the FIR filter of the following stage is presented. The outcome of the simulation showed us that the the filter length in the hybrid filters was remarkably decreased compared to that of the hybrid filters which take the IIR filter as a all-pole model. Although the hybrid filters couldn't obtain the exact linear phase. it was superior to the IIR filters in passband and stopband.

  • PDF