• Title/Summary/Keyword: applicability domain

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Dynamic analysis of frames with viscoelastic dampers: a comparison of damper models

  • Lewandowski, R.;Bartkowiak, A.;Maciejewski, H.
    • Structural Engineering and Mechanics
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    • v.41 no.1
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    • pp.113-137
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    • 2012
  • Frame structures with viscoelastic (VE) dampers mounted on them are considered in this paper. It is the aim of this paper to compare the dynamic characteristics of frame structures with VE dampers when the dampers are modelled by means of different models. The classical rheological models, the model with the fractional order derivative, and the complex modulus model are used. A relatively large structure with VE dampers is considered in order to make the results of comparison more representative. The formulae for dissipation energy are derived. The finite element method is used to derive the equations of motion of the structure with dampers and such equations are written in terms of both physical and state-space variables. The solution to motion equations in the frequency domain is given and the dynamic properties of the structure with VE dampers are determined as a solution to the appropriately defined eigenvalue problem. Several conclusions concerning the applicability of a family of models of VE dampers are formulated on the basis of results of an extensive numerical analysis.

Intelligent Digital Redesign of Biodynamic Model of HIV-1 (HIV-1 바이오 동역학 모델의 지능형 디지털 재설계)

  • Kim Do-Wan;Joo Young-Hoon;Park Jin-Bae
    • Journal of Institute of Control, Robotics and Systems
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    • v.12 no.6
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    • pp.547-553
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    • 2006
  • This paper studies digital control of biodynamic model of HIV-1 via intelligent digital redesign (IDR). The purpose of the IDR is to develop an equivalent digital fuzzy controller maintaining the satisfactory performance of an existing continuous-time fuzzy controller in the sense of the state-matching. Some conditions for the stability as well as the global state-matching are provided.. They are given by the form of the linear matrix inequalities (LMIs) and thereby easily tractable by the convex optimization techniques. The main features of the proposed method are that 1) the generalized control scheme is provided for the multirate as well as the single-rate digital controllers; 2) a new compensated block-pulse function method is applied to closely match the states of the continuous-time and the sampled-data fuzzy systems in the discrete-time domain; 3) the two-step procedure of IDR is presented to prevent the performance degradation caused by the additional stability conditions. The applicability of the proposed approach is shown through the biodynamic model of HIV-1.

Application of Artificial Neural Networks to Predict Dynamic Responses of Wing Structures due to Atmospheric Turbulence

  • Nguyen, Anh Tuan;Han, Jae-Hung;Nguyen, Anh Tu
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.3
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    • pp.474-484
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    • 2017
  • This paper studies the applicability of an efficient numerical model based on artificial neural networks (ANNs) to predict the dynamic responses of the wing structure of an airplane due to atmospheric turbulence in the time domain. The turbulence velocity is given in the form of a stationary Gaussian random process with the von Karman power spectral density. The wing structure is modeled by a classical beam considering bending and torsional deformations. An unsteady vortex-lattice method is applied to estimate the aerodynamic pressure distribution on the wing surface. Initially, the trim condition is obtained, then structural dynamic responses are computed. The numerical solution of the wing structure's responses to a random turbulence profile is used as a training data for the ANN. The current ANN is a three-layer network with the output fed back to the input layer through delays. The results from this study have validated the proposed low-cost ANN model for the predictions of dynamic responses of wing structures due to atmospheric turbulence. The accuracy of the predicted results by the ANN was discussed. The paper indicated that predictions for the bending moments are more accurate than those for the torsional moments of the wing structure.

Robust PID Controller Tuning Technique and Applicationi to Speed Controller Design for BLDC Motors (견실 PID 제어기 조정기법 및 BLDC 모터의 속도제어기 설계에의 응용)

  • Kim, In-Soo;Lee, Young-Jin;Park, Sung-Jun;Park, Han-Woong;Lee, Man-Hyung
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.8
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    • pp.126-133
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    • 2000
  • This paper is a study on robust PID controller tuning technique using the frequency region model matching method.To design the robust PID controller satisfying disturbance attenuation and robust tracking property for a reference input first an {{{{ETA _$\infty$}}}} controller satisfying given performances is designed using an H$_{\infty}$ control method, And then the parameters(proportional gain integral gain and derivation gain) of the robust PID controller with the performances of the desinged H$_{\infty}$ controller are determined using the model matching method at frequency domain. in this paper this PID controller tuning technique is applied to PID speed controller design for BLDC motors. Consequently simulation results show that the proposed PID speed controller satisfies load torque disturbance attenuation and robust tracking property and this study has usefulness and applicability for the speed control system; design of BLDC motors.

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Discourse Analysis for Robust Spoken Dialogue System (강건한 음성 대화 시스템을 위한 담화분석 기술)

  • Lee, Chung-Hee;Jang, Myung-Gil;Oh, Hyo-Jung;Seo, Young-Hoon
    • Journal of KIISE:Computing Practices and Letters
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    • v.16 no.10
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    • pp.1005-1009
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    • 2010
  • Elliptical and anaphoric utterances occur frequently during spoken dialogue. Because discourse analysis rests on the basic premise that linguistic items cannot be understood without reference to the context, ellipsis and anaphora resolution plays an important role in discourse analysis. In this paper, we present a spoken dialogue system improving the robustness at dialogue level based on discourse analysis, such as anaphora and ellipsis resolution. The applicability and effectiveness of the proposed method is evaluated in the TV domain.

Numerical prediction of a flashing flow of saturated water at high pressure

  • Jo, Jong Chull;Jeong, Jae Jun;Yun, Byong Jo;Moody, Frederick J.
    • Nuclear Engineering and Technology
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    • v.50 no.7
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    • pp.1173-1183
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    • 2018
  • Transient fluid velocity and pressure fields in a pressurized water reactor (PWR) steam generator (SG) secondary side during the blowdown period of a feedwater line break (FWLB) accident were numerically simulated employing the saturated water flashing model. This model is based on the assumption that compressed water in the SG is saturated at the beginning and decompresses into the two-phase region where saturated vapor forms, creating a mixture of steam bubbles in water by bulk boiling. The numerical calculations were performed for two cases of which the outflow boundary conditions are different from each other; one is specified as the direct blowdown discharge to the atmosphere and the other is specified as the blowdown discharge to an extended calculation domain with atmospheric pressure on its boundary. The present simulation results obtained using the two different outflow boundary conditions were discussed through a comparison with the predictions using a simple non-flashing model neglecting the effects of phase change. In addition, the applicability of each of the non-flashing water discharge and saturated water flashing models for the confirmatory assessments of new SG designs was examined.

Terahertz Spectral Characteristics of Electrolyte Solutions under Different Magnetic Fields

  • Shao, Siyu;Huang, Haiyun;Peng, Bo;Wang, Guoyang;Ye, Ping;Wang, Jiahui;Su, Bo;Cui, Hailin;Zhang, Cunlin
    • Current Optics and Photonics
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    • v.6 no.3
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    • pp.337-343
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    • 2022
  • Microfluidic chips are new devices that can manipulate liquids at the micrometer level, and terahertz (THz) time-domain spectroscopy has good applicability in biochemical detection. The combination of these two technologies can shorten the distance between sample and THz wave, reduce THz wave absorption by water, and more effectively analyze the kinetics of biochemical reactions in aqueous solutions. This study investigates the effects of different external magnetic field intensities on the THz transmission characteristics of deionized water, CuSO4, CuCl2, (CH3COO)2Cu, Na2SO4, NaCl, and CH3COONa; the THz spectral intensity of the sample solutions decrease with increasing intensity of the applied magnetic field. Analysis shows that the magnetic field leads to a change in the dipole moment of water molecules in water and electrolyte solutions, which enhances not only the hydrogen-bond networking ability of water but also the hydration around ions in electrolyte solutions, increasing the number of hydrogen bonds. Increasing the intensity of this magnetic field further promotes the hydrogen-bond association between water molecules, weakening the THz transmission intensity of the solution.

A modularized numerical framework for the process-based total system performance assessment of geological disposal systems

  • Kim, Jung-Woo;Jang, Hong;Lee, Dong Hyuk;Cho, Hyun Ho;Lee, Jaewon;Kim, Minjeong;Ju, Heejae
    • Nuclear Engineering and Technology
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    • v.54 no.8
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    • pp.2828-2839
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    • 2022
  • This study developed a safety assessment tool for geological disposal systems called APro, a systemically integrated modeling system based on modularizing and coupling the processes which need to be considered in a geological disposal system. Thermal, hydraulic, chemical, canister failure, radionuclide release and transport processes were considered in the current version of APro. Each of the unit processes in APro consists of a single Default Module, and several Alternative Modules which can increase the flexibility of the model. As an initial stage of developing the modularization concept and modeling interface, the Default Modules of each unit process were described, with one Alternative Module of chemical process. The computation part of APro is mainly a MATLAB workspace controlling COMSOL and PHREEQC, which are coupled by an operator splitting scheme. The APro model domain is a stylized geological disposal system employing the Swedish disposal concept (KBS-3 type), but the repository layout can be freely adjusted. In order to show the applicability of APro to the total system performance assessment of geological disposal system, some sample simulations were conducted. From the results, it was confirmed that coupling of the thermal and hydraulic processes and coupling of the canister failure and the radionuclide release processes were well reflected in APro. In addition, the technical connectivity between COMSOL and PHREEQC was also confirmed.

Stress status classification based on EEG signals (뇌파 신호 기반 스트레스 상태 분류)

  • Kang, Jun-Su;Jang, Giljin;Lee, Minho
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.16 no.3
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    • pp.103-108
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    • 2016
  • In daily life, humans get stress very often. Stress is one of the important factors of healthy life and closely related to the quality of life. Too much stress is known to cause hormone imbalance of our body, and it is observed by the brain and bio signals. Based on this, the relationship between brain signal and stress is explored, and brain signal based stress index is proposed in our work. In this study, an EEG measurement device with 32 channels is adopted. However, only two channels (FP1, FP2) are used to this study considering the applicability of the proposed method in real enveironment, and to compare it with the commercial 2 channel EEG device. Frequency domain features are power of each frequency bands, subtraction, addition, or division by each frequency bands. Features in time domain are hurst exponent, correlation dimension, lyapunov exponent, etc. Total 6 subjects are participated in this experiment with English sentence reading task given. Among several candidate features, ${\frac{{\theta}\;power}{mid\;{\beta}\;power}}$ shows the best test performance (70.8%). For future work, we will confirm the results is consistent in low price EEG device.

Application of Time Domain Reflectometry to Estimate Curing Process of Cementitious Grout (시계열반사계를 이용한 시멘트계열 지반보강재의 양생과정 평가)

  • Jun, Minu;Cho, Hyunmuk;Lee, Eun Sang;Hong, Won-Taek
    • Journal of the Korean Geotechnical Society
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    • v.40 no.3
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    • pp.85-91
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    • 2024
  • To realize stable use of ground treated with cementitious materials, the curing process must be evaluated. In this study, a time domain reflectometry (TDR) measurement system was employed to evaluate the curing process of cementitious grout based on the electromagnetic property. A coated probe was manufactured to prevent electrical connection between the electrodes by the electrically conductive cementitious grout, and a calibration process was performed to estimate the actual relative permittivity using the coated probe. To assess the curing process of cementitious grout using the TDR measurement system, cementitious grout with added retarder was prepared with a water-to-cement ratio of 45%. A preliminary measurement was conducted immediately after pouring the cementitious grout into the mold to test the applicability of the coated probe, and TDR signals and relative permittivity were measured at 3~288 hours of curing time. The experimental results demonstrate that the relative permittivity of the cementitious grout immediately after pouring was greater than 100, decreased rapidly over time, and converged to approximately 13.8 at 144 hours, which is considered the fully cured time. This findings of this study demonstrate that the TDR measurement system with a coated probe is applicable to electrically conductive materials. In addition, the TDR measurement system can be used effectively to monitor the curing process of cementitious grout based on electromagnetic properties.