• Title/Summary/Keyword: Reduced Model

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Reduced Quasi-Dimensional Combustion Model of the Direct Injection Diesel Engine for Performance and Emissions Predictions

  • Jung, Dohoy;Assanis, Dennis N.
    • Journal of Mechanical Science and Technology
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    • v.18 no.5
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    • pp.865-876
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    • 2004
  • A new concept of reduced quasi-dimensional combustion model for a direct injection diesel engine is developed based on the previously developed quasi-dimensional multi-zone model to improve the computational efficiency. In the reduced model, spray penetration and air entrainment are calculated for a number of zones within the spray while three zones with aggregated spray zone concept are used for the calculation of spray combustion and emission formation processes. It is also assumed that liquid phase fuel appears only near the nozzle exit during the breakup period and that spray vaporization is immediate in order to reduce the computational time. Validation of the reduced model with experimental data demonstrated that the new model can predict engine performance and NO and soot emissions reasonably well compared to the original model. With the new concept of reduced model, computational efficiency is significantly improved as much as 200 times compared to the original model.

A New Approach to Reduced-Order Modeling of Multi-Module Converters

  • Park, Byung-Cho
    • Journal of Electrical Engineering and information Science
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    • v.2 no.4
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    • pp.92-98
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    • 1997
  • This paper presents a new approach to obtaining a reduced-order model for multi-module converters. The proposed approach can be used to derive the reduced-order model for a wide class of multi-module converters including pulse-width-modulated (PWM) converters, soft-switched PWM converters, and resonant converters. The reduced-order model has the structure of a conventional single-module converter while preserving the dynamics of the original multi-module converter. Derivation procedures and the use of the reduced-order model is demonstrated using a three-module boost converter.

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Toxicity Evaluation of Complex Metal Mixtures Using Reduced Metal Concentrations: Application to Iron Oxidation by Acidithiobacillus ferrooxidans

  • Cho, Kyung-Suk;Ryu, Hee-Wook;Choi, Hyung-Min
    • Journal of Microbiology and Biotechnology
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    • v.18 no.7
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    • pp.1298-1307
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    • 2008
  • In this study, we investigated the inhibition effects of single and mixed heavy metal ions ($Zn^{2+},\;Ni^{2+},\;Cu^{2+},\;and\;Cd^{2+}$) on iron oxidation by Acidithiobacillus ferrooxidans. Effects of metals on the iron oxidation activity of A. ferrooxidans are categorized into four types of patterns according to its oxidation behavior. The results indicated that the inhibition effects of the metals on the iron oxidation activity were noncompetitive inhibitions. We proposed a reduced inhibition model, along with the reduced inhibition constant ($\alpha_i$), which was derived from the inhibition constant ($K_I$) of individual metals and represented the tolerance of a given inhibitor relative to that of a reference inhibitor. This model was used to evaluate the toxicity effect (inhibition effect) of metals on the iron oxidation activity of A. ferrooxidans. The model revealed that the iron oxidation behavior of the metals, regardless of metal systems (single, binary, ternary, or quaternary), is closely matched to that of any reference inhibitor at the same reduced inhibition concentration, $[I]_{reduced}$, which defines the ratio of the inhibitor concentration to the reduced inhibition constant. The model demonstrated that single metal systems and mixed metal systems with the same reduced inhibitor concentrations have similar toxic effects on microbial activity.

SIMPLIFIED APPROACH TO VALUATION OF VULNERABLE EXCHANGE OPTION UNDER A REDUCED-FORM MODEL

  • Huh, Jeonggyu;Jeon, Jaegi;Kim, Geonwoo
    • East Asian mathematical journal
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    • v.37 no.1
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    • pp.79-85
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    • 2021
  • In this paper, we investigate the valuation of vulnerable exchange option that has credit risk of option issuer. The reduced-form model is used to model credit risk. We assume that credit event is determined by the jump of the counting process with stochastic intensity, which follows the mean reverting process. We propose a simple approach to derive the closed-form pricing formula of vulnerable exchange option under the reduced-form model and provide the pricing formula as the standard normal cumulative function.

Development of a reduced-order distillation model and real-time tuning using the extended kalmen filter (증류공정 차수감소 모델의 개발 extended kalmen filter에 의한 실시간대에서의 조정)

  • 정재익;최상열;이광순
    • 제어로봇시스템학회:학술대회논문집
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    • 1988.10a
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    • pp.466-470
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    • 1988
  • A tunable reduced-order distillation model is proposed for real-time applications. To develop the model, a binary distillation column with MaCabe-Thiele assumptions was considered first and then the governing equations for the column were reduced to a simplified vector differential equations using the collocation method combined with cubic spline interpolation function. The final reduced-order model has four tuning parameters, relative volatilities and liquid holdups for rectifying and stripping sections, respectively. To assess the applicability of the developed model,the real-time adjustment of the model was tried by recursively updating the tuning parameters using the BKF algorithm. As a result, it was found that the reduced-model follows the simulated distillation process very closely as the parameters are improved.

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Wing Optimization based on a Reduced System (축소시스템 기반 비행체 날개 최적화 연구)

  • Kim, Hyun-Gi;Choi, In-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.10
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    • pp.4411-4417
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    • 2012
  • The present study proposes the optimization of wing structure base on reduced model which assures the solution accuracy and computational efficiency. Well-constructed reduced model assures the accurate result in the eigenvalue problem, dynamic analysis or sensitivity of design optimization. Reduced system is classified into the reduce-order model based on structural modes and the reduced system based on degrees of freedom. Because this study uses the reduced system based on degrees of freedom, it is important to select the dominant degrees of freedom properly. For this work, robust selection method, two-level selection scheme, is employed and IRS(Improved Reduced System) is applied to construct the final reduced system. In the optimization process based on the reduced system, all of the equivalent stress, eigenvalue and design sensitivities are calculated from the reduced system. Through a numerical example, it is shown that the present optimization methodology based on the reduction method can provide an optimal results for objective function satisfying constraint condition.

Model reduction techniques for high-rise buildings and its reduced-order controller with an improved BT method

  • Chen, Chao-Jun;Teng, Jun;Li, Zuo-Hua;Wu, Qing-Gui;Lin, Bei-Chun
    • Structural Engineering and Mechanics
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    • v.78 no.3
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    • pp.305-317
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    • 2021
  • An AMD control system is usually built based on the original model of a target building. As a result, the fact leads a large calculation workload exists. Therefore, the orders of a structural model should be reduced appropriately. Among various model-reduction methods, a suitable reduced-order model is important to high-rise buildings. Meanwhile, a partial structural information is discarded directly in the model-reduction process, which leads to the accuracy reduction of its controller design. In this paper, an optimal technique is selected through comparing several common model-reduction methods. Then, considering the dynamic characteristics of a high-rise building, an improved balanced truncation (BT) method is proposed for establishing its reduced-order model. The abandoned structural information, including natural frequencies, damping ratios and modal information of the original model, is reconsidered. Based on the improved reduced-order model, a new reduced-order controller is designed by a regional pole-placement method. A high-rise building with an AMD system is regarded as an example, in which the energy distribution, the control effects and the control parameters are used as the indexes to analyze the performance of the improved reduced-order controller. To verify its effectiveness, the proposed methodology is also applied to a four-storey experimental frame. The results demonstrate that the new controller has a stable control performance and a relatively short calculation time, which provides good potential for structural vibration control of high-rise buildings.

Application of process monitoring with reduced order model and EKF to distillation column (차수 감소 모델과 EKF를 이용한 공정 모니터링의 응용)

  • 김태민;양대륙
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.1766-1769
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    • 1997
  • Fast and accurate distillation design requires a model that significantly reduces the problem size withour loss of accruacy is especially suitable for rela-time applicatoins. the reduced order model is obtained by use of Principal Component Anlysis(PCA). Then the extended Kalman filter and the Recursie Predictiuon Error(RPE) mehtod are appliced to identify the model parameters and the feed compostion form the measuremenets of the coumn. as a consequence it is found that the model reduction thechique can account for the dynamics of the rigorous distillation model and not only the model parameters, bu also the feed compostion can be identified efficiently. this technique is applied to industrial operation data verify the performance of reduced order model.

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Suppressive Effects of Gamisojaganggi-tang on Immunopathogenesis in OVA-induced Asthma Model (가미소자기탕(加味蘇子氣湯)이 천식 유발 병태 모델에서 분자 및 조직병리학적 변화에 미치는 영향)

  • An, Hwang-Yong;Kim, Dong-Hee
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.20 no.5
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    • pp.1159-1165
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    • 2006
  • This study was done to investigate the effects of Gamisojaganggi-tang(GSGT) on immunopathologic changes in OVA-induced asthma model of mice. Pathologic indicators associated with this immune disease, which include cytokines, the number of immune-cells, immunoglobin E (IgE), were examined, and histological changes of bronchial tissues were also examined. The administration of GSGT significantly reduced the lung weight compared with control mice of OVA-induced asthma model. The administration of GSGT significantly reduced the number of total cells in BALF compared with control mice of OVA-induced asthma model. The administration of GSGT significantly reduced the number of eosinophil in BALF compared with control mice of OVA-induced asthma model. The administration of GSGT insignificantly increased the number of monocyte in BALF compared with control mice of OVA-induced asthma model. The administration of GSGT significantly reduced the number of lymphocyte in BAL compared with control mice of OVA-induced asthma model. The administration of GSGT significantly reduced the gene expression of eotaxin in lung tissue compared with control mice of OVA-induced asthma model. The administration of GSGT insignificantly reduced the IL-4 and IL-5 production in BALF compared with control mice of OVA-induced asthma model. The administration of GSGT insignificantly reduced the levels of total IgE and ovalbumin-specific IgE in BALF. The administration of GSGT significantly reduced the levels of ovalbumin-specific IgE whereas the serum levels of total IgE were insignificantly reduced compared with control mice of OVA-induced asthma model. The administration of GSGT moderately reduced bronchial alveolar narrowing, bronchiovascular edema and increase in the size of alveolar space, which shown in control mice of OVA-induced asthma model, in a dose dependent manner. Furthermore, GSGT reduced invasion of inflammatory cells, and proliferation of smooth muscle cells in bronchial tissue. These results suggested that GSGT has suppressive effects on pathologic changes associated with disease progression in asthma through the modulation of immune system. GSGT has potential to use as an anti-asthmatic agents.

A New Combined Approximation for the Reduction of Discrete-Time Systems Using Routh Stability Array and MSE (이감직신간 제어계에 있어서 Routh안정기열과 MSE 을 이용한 새로운 혼합형 모델 절기법)

  • 권오신;김성중
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.36 no.8
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    • pp.584-593
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    • 1987
  • A new combined approximation method using Routh stability array and mean-square error (MSE) method is proposed for deriving reduced-order z-transter functions for discrete time systems. The Routh stability array is used to obtain the reduced-order denominator polynomial, and the numerator polynomial is obtained by minimizing the mean-square error between the unit step responses of the original system and reduced model. The advantages of the new combined approximation method are that the reduced model is always stable provided the original model is stable and the initial and steady-state characteristics of the original model can be preserved in the reduced model.