• Title/Summary/Keyword: Square-root operator

Search Result 23, Processing Time 0.025 seconds

Suggestion for a splitting technique of the square-root operator of three dimensional acoustic parabolic equation based on two variable rational approximant with a factored denominator (인수분해 된 분모를 갖는 두 변수 유리함수 근사에 기반한 3차원 음향 포물선 방정식 제곱근 연산자의 분할기법 제안)

  • Lee, Keunhwa
    • The Journal of the Acoustical Society of Korea
    • /
    • v.36 no.1
    • /
    • pp.1-11
    • /
    • 2017
  • In this study, novel approximate form of the square-root operator of three dimensional acoustic Parabolic Equation (3D PE) is proposed using a rational approximant for two variables. This form has two advantages in comparison with existing approximation studies of the square-root operator. One is the wide-angle capability. The proposed form has wider angle accuracy to the inclination angle of ${\pm}62^{\circ}$ from the range axis of 3D PE at the bearing angle of $45^{\circ}$, which is approximately three times the angle limit of the existing 3D PE algorithm. Another is that the denominator of our approximate form can be expressed into the product of one-dimensional operators for depth and cross-range. Such a splitting form is very preferable in the numerical analysis in that the 3D PE can be easily transformed into the tridiagonal matrix equation. To confirm the capability of the proposed approximate form, comparative study of other approximation methods is conducted based on the phase error analysis, and the proposed method shows best performance.

Stability Improved Split-step Parabolic Equation Model

  • Kim, Tae-Hyun;Seong, Woojae
    • The Journal of the Acoustical Society of Korea
    • /
    • v.21 no.3E
    • /
    • pp.105-111
    • /
    • 2002
  • The parabolic equation technique provides an excellent model to describe the wave phenomena when there exists a predominant direction of propagation. The model handles the square root wave number operator in paraxial direction. Realization of the pseudo-differential square root operator is the essential part of the parabolic equation method for its numerical accuracy. The wide-angled approximation of the operator is made based on the Pade series expansion, where the branch line rotation scheme can be combined with the original Pade approximation to stabilize its computational performance for complex modes. The Galerkin integration has been employed to discretize the depth-dependent operator. The benchmark tests involving the half-infinite space, the range independent and dependent environment will validate the implemented numerical model.

SQUARE QUADRATIC PROXIMAL METHOD FOR NONLINEAR COMPLIMENTARITY PROBLEMS

  • Bnouhachem, Abdellah;Ou-yassine, Ali
    • Communications of the Korean Mathematical Society
    • /
    • v.34 no.2
    • /
    • pp.671-684
    • /
    • 2019
  • In this paper, we propose a new interior point method for solving nonlinear complementarity problems. In this method, we use a new profitable searching direction and instead of using the logarithmic quadratic term, we use a square root quadratic term. We prove the global convergence of the proposed method under the assumption that F is monotone. Some preliminary computational results are given to illustrate the efficiency of the proposed method.

Prediction of Barge Ship Roll Response Amplitude Operator Using Machine Learning Techniques

  • Lim, Jae Hwan;Jo, Hyo Jae
    • Journal of Ocean Engineering and Technology
    • /
    • v.34 no.3
    • /
    • pp.167-179
    • /
    • 2020
  • Recently, the increasing importance of artificial intelligence (AI) technology has led to its increased use in various fields in the shipbuilding and marine industries. For example, typical scenarios for AI include production management, analyses of ships on a voyage, and motion prediction. Therefore, this study was conducted to predict a response amplitude operator (RAO) through AI technology. It used a neural network based on one of the types of AI methods. The data used in the neural network consisted of the properties of the vessel and RAO values, based on simulating the in-house code. The learning model consisted of an input layer, hidden layer, and output layer. The input layer comprised eight neurons, the hidden layer comprised the variables, and the output layer comprised 20 neurons. The RAO predicted with the neural network and an RAO created with the in-house code were compared. The accuracy was assessed and reviewed based on the root mean square error (RMSE), standard deviation (SD), random number change, correlation coefficient, and scatter plot. Finally, the optimal model was selected, and the conclusion was drawn. The ultimate goals of this study were to reduce the difficulty in the modeling work required to obtain the RAO, to reduce the difficulty in using commercial tools, and to enable an assessment of the stability of medium/small vessels in waves.

Prestack Datuming by Wavefield Depth Extrapolation using the DSR Equation (DSR 연산자에 의한 파동장 외삽을 이용한 중합전 데이터밍)

  • Ji Jun
    • Geophysics and Geophysical Exploration
    • /
    • v.2 no.1
    • /
    • pp.54-62
    • /
    • 1999
  • This paper describes a datuming scheme for a prestack dataset which uses wavefield depth extrapolation. The formulation of the prestack datuming algorithm is performed by finding the adjoint operator to the corresponding forward prestack wavefield extrapolation from a flat surface to an irregular surface. Here I used double-square-root (DSR) equation to extrapolate wavefield in prestack sense. This correspond to the forward model of the well known `survey sinking` prestack imaging algorithm.

  • PDF

Development of the Fault Diagnostic System on the Rotating Machinery Using Vibration Signal (진동 신호를 이용한 회전기기 고장 진단 시스템의 개발)

  • Lee Choong-Hwi;Sim Hyoun Jin;Oh Jae-Eung;Yoon Lee Jng
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.21 no.12
    • /
    • pp.75-83
    • /
    • 2004
  • With the rotating machinery getting more accurate and diversified, the necessity fur an appropriate diagnosis technique and maintenance system has been greatly recognized. However, until now, the operator has executed a monitoring of the machine by the senses or simple the change of RMS (root mean Square) value. So, the diagnostic expert system using the fuzzy inference which the operator can judge easily and expertly a condition of the machine is developed through this study. In this paper, the hardware and software of the diagnostic expert system was composed and the identification of the diagnostic performance of the developed system for 5 fault phenomena was carried out.

Integer-Valued HAR(p) model with Poisson distribution for forecasting IPO volumes

  • SeongMin Yu;Eunju Hwang
    • Communications for Statistical Applications and Methods
    • /
    • v.30 no.3
    • /
    • pp.273-289
    • /
    • 2023
  • In this paper, we develop a new time series model for predicting IPO (initial public offering) data with non-negative integer value. The proposed model is based on integer-valued autoregressive (INAR) model with a Poisson thinning operator. Just as the heterogeneous autoregressive (HAR) model with daily, weekly and monthly averages in a form of cascade, the integer-valued heterogeneous autoregressive (INHAR) model is considered to reflect efficiently the long memory. The parameters of the INHAR model are estimated using the conditional least squares estimate and Yule-Walker estimate. Through simulations, bias and standard error are calculated to compare the performance of the estimates. Effects of model fitting to the Korea's IPO are evaluated using performance measures such as mean square error (MAE), root mean square error (RMSE), mean absolute percentage error (MAPE) etc. The results show that INHAR model provides better performance than traditional INAR model. The empirical analysis of the Korea's IPO indicates that our proposed model is efficient in forecasting monthly IPO volumes.

Operating Criteria of Core Exit Temperature in Nuclear Power Plant with using Channel Statistical Allowance (총채널 불확실도를 적용한 원전 노심출구온도의 운전가능 판정기준)

  • Sung, Je Joong;Joo, Yoon Duk;Ha, Sang Jun
    • Journal of the Korean Society of Safety
    • /
    • v.29 no.6
    • /
    • pp.166-171
    • /
    • 2014
  • Nuclear power plants are equipped with the reactor trip system (RTS) and the engineered safety features actuation system (ESFAS) to improve safety on the normal operation. In the event of the design basis accident (DBA), a various of post accident monitor(PAM)systems support to provide important details (e.g. Containment pressure, temperature and pressure of reactor cooling system and core exit temperature) to determine action of main control room (MCR). Operator should be immediately activated for the accident mitigation with the information. Especially, core exit temperature is a critical parameter because the operating mode converts from normal mode to emergency mode when the temperature of core exit reaches $649^{\circ}C$. In this study, uncertainty which was caused by exterior environment, characteristic of thermocouple/connector and accuracy of calibrator/indicator was evaluated in accordance with ANSI-ISA 67.04. The square root of the sum of square (SRSS) methodology for combining uncertainty terms that are random and independent was used in the synthesis. Every uncertainty that may exist in the hardware which is used to measure the core exit temperature was conservatively applied and the associative relation between the elements of uncertainty was considered simultaneously. As a result of uncertainty evaluation, the channel statistical allowance (CSA) of single channel of core exit temperature was +1.042%Span. The range of uncertainty, -0.35%Span ($-4.05^{\circ}C$) ~ +2.08%Span($24.25^{\circ}C$), was obtained as the operating criteria of core exit temperature.

Simultaneous Measurement of Vibration and Applied Forces at a Power Tool Handle for the Reduction of Random Error When valuating Hand-transmitted Vibration (수전달 진동평가량의 랜덤오차 저감을 위한 공구 핸들에서의 진동과 작용력의 동시 측정)

  • Choi, Seok-Hyun;Jang, Han-Kee;Park, Tae-Won
    • Transactions of the Korean Society for Noise and Vibration Engineering
    • /
    • v.15 no.4 s.97
    • /
    • pp.404-411
    • /
    • 2005
  • To increase accurateness and reliability of the evaluation of power tool vibration transmitted to an operator, it is necessary to measure the grip and feed forces during the measurement of hand-transmitted vibration. In the study a system was invented to measure the vibration and the grip and/or feed force, which consists of a measurement handle and a PC with a data acquisition system and the corresponding software. Strain gauges and an accelerometer were mounted on the handle surface for the simultaneous measurement of the forces and the vibration. The program in the system makes it possible to monitor the grip and feed force during the tool operation so that the operator keeps the applying forces within the pre-determined range. Investigating the vibration total values, frequency-weighted root-mean-square accelerations at the handle, obtained in repetition for each power tool with control of the grip and feed force showed more consistency than those measured without force control. By using the system the experimenter can reduce random error of the measured vibration.

The Simultaneous Measurement of Vibration and Applied forces at a Power tool handle for the Evaluation of Hand-transmitted Vibration (수전달 진동 평가를 위한 공구 핸들에서의 진동과 작용력의 동시 측정)

  • Choi, Seok-Hyun;Jang, Han-Kee;Park, Tae-Won
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2004.11a
    • /
    • pp.689-694
    • /
    • 2004
  • To increase accurateness and reliability of the evaluation of power tool vibration transmitted to an operator, it is necessary to measure grip and feed forces during the measurement of hand-transmitted vibration. In the study a system was invented to measure the vibration and the grip and/or feed force, which consists of a measurement handle and a PC with data acquisition system and the software. Strain gauges and an accelerometer were mounted on the handle for the simultaneous measurement of the forces and the vibration. The program in the system makes it possible to monitor the grip and feed force during the tool operation so that the operator keeps the applying forces within the pre-determined range. Investigating the vibration total values, frequency-weighted root mean square accelerations at the handle, obtained at various conditions with control of the grip and feed force showed more consistency than those measured without force control. By using the system the experimenter can reduce uncertainty of the measured vibration.

  • PDF