• Title/Summary/Keyword: power estimation

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Feasibility study of using triple-energy CT images for improving stopping power estimation

  • Yejin Kim;Jin Sung Kim ;Seungryong Cho
    • Nuclear Engineering and Technology
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    • v.55 no.4
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    • pp.1342-1349
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    • 2023
  • The planning accuracy of charged particle therapy (CPT) is subject to the accuracy of stopping power (SP) estimation. In this study, we propose a method of deriving a pseudo-triple-energy CT (pTECT) that can be achievable in the existing dual-energy CT (DECT) systems for better SP estimation. In order to remove the direct effect of errors in CT values, relative CT values according to three scanning voltage settings were used. CT values of each tissue substitute phantom were measured to show the non-linearity of the values thereby suggesting the absolute difference and ratio of CT values as parameters for SP estimation. Electron density, effective atomic number (EAN), mean excitation energy and SP were calculated based on these parameters. Two of conventional methods were implemented and compared to the proposed pTECT method in terms of residuals, absolute error and root-mean-square-error (RMSE). The proposed method outperformed the comparison methods in every evaluation metrics. Especially, the estimation error for EAN and mean excitation using pTECT were converging to zero. In this proof-of-concept study, we showed the feasibility of using three CT values for accurate SP estimation. Our suggested pTECT method indicates potential clinical utility of spectral CT imaging for CPT planning.

An Experimental Study on the Estimation Flow-rate of Venturi Pump Using LightGBM (LightGBM을 이용한 수력 펌프 유량 추정의 실험적 연구)

  • Jin Beom Jeong;Jihwan Lee;Myeongcheol Kang
    • Journal of Drive and Control
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    • v.20 no.4
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    • pp.123-132
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    • 2023
  • In disaster situations, to facilitate rapid drainage, electric underwater pumps are installed manually. This poses a high risk of electric shock accidents due to a short circuit, and a lot of time is required for hose connection and installation of electrical devices. To solve these problems, a Venturi pump using the venturi effect without external power is used. However, Venturi pumps that operate without external power make it difficult to install flow sensors such as electric devices; consequently, it is difficult to check the real-time flow rate. This paper proposes a flow estimation logic to replace the function of the flow sensor for the venturi pump . To develop the flow estimation logic, the flow characteristics of the venturi pump, according to the operating conditions, were checked. After that, the relationship with the flow rate of the venturi pump was defined using a pressure sensor corresponding to a low-cost sensor. Finally, an analysis of the estimation error was performed using the developed flow estimation logic.

Minimum Density Power Divergence Estimation for Normal-Exponential Distribution (정규-지수분포에 대한 최소밀도함수승간격 추정법)

  • Pak, Ro Jin
    • The Korean Journal of Applied Statistics
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    • v.27 no.3
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    • pp.397-406
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    • 2014
  • The minimum density power divergence estimation has been a popular topic in the field of robust estimation for since Basu et al. (1988). The minimum density power divergence estimator has strong robustness properties with the little loss in asymptotic efficiency relative to the maximum likelihood estimator under model conditions. However, a limitation in applying this estimation method is the algebraic difficulty on an integral involved in an estimation function. This paper considers a minimum density power divergence estimation method with approximated divergence avoiding such difficulty. As an example, we consider the normal-exponential convolution model introduced by Bolstad (2004). The estimated divergence in this case is too complicated; consequently, a Laplace approximation is employed to obtain a manageable form. Simulations and an empirical study show that the minimum density power divergence estimators based on an approximated estimated divergence for the normal-exponential model perform adequately in terms of bias and efficiency.

Estimation-based Watermarking Algorithm with Low Density Parity Check (LDPC) Codes (LDPC를 이용한 예측 기반 워터마킹 알고리듬)

  • Lim, Jae-Hyuck;Won, Chee-Sun
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.44 no.1
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    • pp.76-84
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    • 2007
  • The goal of this paper is to improve the watermarking performance using the following two methods; watermark estimation and low density parity check (LDPC) codes. For a blind watermark decoding, the power of a host image, which is hundreds times greater than the watermark power, is the main noise source. Therefore, a technique that can reduce the effect of the power of the host image to the detector is required. To this end, we need to estimate watermark from the watermarked image. In this paper, the watermark estimation is done by an adaptive estimation method with the generalized Gaussian distribution modeling of sub-band coefficients in the wavelet domain. Since the watermark capacity as well as the error rate can be improved by adopting optimum decoding principles and error correcting codes (ECC), we employ the LDPC codes for the decoding of the estimated watermark. Also, in LDPC codes, the knowledge about the noise power can improve the error correction capability. Simulation results demonstrate the superior performance of the proposed algorithm comparing to LDPC decoding with other estimation-based watermarking algorithms.

Estimation of Distributed and Joint-excited Input Power for Power Flow Analysis (파워흐름해석을 위한 분포가진 및 연결부 가진의 입력파워추정 연구)

  • Kim, Dong-Jin;Hong, Suk-Yoon
    • Journal of the Society of Naval Architects of Korea
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    • v.43 no.5 s.149
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    • pp.597-603
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    • 2006
  • The estimations of distributed and joint-excited input power for Power Flow Analysis are accomplished in this paper. Using Fourier transform, the displacements of infinite structures are derived, and the input power of distributed excitation can be estimated. The obtained results compare the real input power with the estimation of input power. When the exciting force acts on the joint of coupled structures, it is estimating the power that is transferred to each structure. Appling this input power, the results of energy density and intensity of Power Flow Analysis can be compared with the classical solutions.

Design and Implementation of Instantaneous Power Estimation Algorithm for Unified Power Conditioner

  • S., Sindhu;M.R., Sindhu;Nambiar, T.N.P.
    • Journal of Power Electronics
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    • v.19 no.3
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    • pp.815-826
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    • 2019
  • This paper discusses a simple control approach for a Unified Power Conditioner (UPC) system to achieve power quality compensation at the point of common coupling in distribution systems. The proposed Instantaneous Power Estimation Algorithm (IPEA) for shunt and series active power filters uses a simple mathematical concept that reduces the complexity in the design of the controller. The performance of a UPC is verified with a system subjected to voltage distortions, sags/swells and unbalanced loads using MATLAB/SIMULINK. The simulation study shows that a UPC with the proposed control algorithm can effectively compensate for voltage and current harmonics, unbalance and reactive power. The control algorithm is experimentally implemented using dSPACE DS1104 and its effectiveness has been verified.

A Sensorless Control of IPMSM using the Improving Instantaneous Reactive Power Compensator (개선된 순시무효전력 보상기를 이용한 IPMSM의 센서없는 속도제어)

  • La, Jae Du
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.10
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    • pp.1303-1307
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    • 2018
  • A improving sensorless compensator for the IPMSM(Interior Permanent Magnet Synchronous Motor) drive system is proposed. Generally, the motor drive system is required the robust parameter variation and disturbance. The speed estimation methods of the conventional IRP(Instantaneous Reactive Power) compensator is improved by the speed estimation techniques of the current model observer with the proposed instantaneous reactive power compensator. Performance evaluations of the novel speed error compensator and sensorless control system are carried out by the experiments.

Cutting Force Estimation Using Spindle Motor Power (주축 모터 동력을 이용한 절삭력 예측)

  • 최영준;김기대;주종남
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.1088-1094
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    • 1997
  • An indirect cutting torque and cutting force estimation method is presented. This method uses a time-domain model between the spindle motor power, which calculated form measured spindle motor current and voltage. Spindle motor power is linear with cutting torque in this model. The cutting force is proportional to the cutting torque. Using trial cut, parameters are determined. Static sensitivity is suitable for various cutting conditions. The presented method is verified under several cutting tests on the CNC horizontal machining center.

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State Estimation in Power System by Efficient Elimination Method of Bad Data (효과적인 불량정보제거법에 의한 전력계통에서의 장웅추정에 관한 연구)

  • 김준현;이종범
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.33 no.9
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    • pp.364-371
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    • 1984
  • This paper describes a method for the state estimation in electric power system. The state values are estimated through the weighted least square method considering the bad data. Then, the bad data are identified by using sensitivity coefficients of power system after being detected the bad data through the distribution of T. This method was applied to the model power system, and, the results of test for proposed method are given.

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Sensorless Control of the Synchronous Reluctance Machine

  • Kilthau, A.;Pacas, J.M.
    • Journal of Power Electronics
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    • v.2 no.2
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    • pp.95-103
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    • 2002
  • The paper deals with the control of the synchronous reluctance machine without position senser. A method for the computation of the transformation angle out of terminal voltages and currents is presented. The injection of test signals allows operation at zero speed. Fundamental for this control scheme is the angle estimation method over the whole operating range including field-weakening is discussed in detail. The implementation of the angle estimation method in a rotor-oriented control scheme and practical results are demonstrated.