• Title/Summary/Keyword: The Transient Energy Function

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A novel approach in voltage transient technique for the measurement of electron mobility and mobility-lifetime product in CdZnTe detectors

  • Yucel, H.;Birgul, O.;Uyar, E.;Cubukcu, S.
    • Nuclear Engineering and Technology
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    • v.51 no.3
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    • pp.731-737
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    • 2019
  • In this study, a new measurement method based on voltage transients in CdZnTe detectors response to low energy photon irradiations is applied to measure the electron mobility (${\mu}_e$) and electron mobility-lifetime product $({\mu}{\tau})_e$ in a CdZnTe detector. In the proposed method, the pulse rise times are derived from low energy photon response to 59.5 keV($^{241}Am$), 88 keV($^{109}Cd$) and 122 keV($^{57}Co$) ${\gamma}-rays$ for the irradiation of the cathode surface at each detector for different bias voltages. The electron $({\mu}{\tau})_e$ product was then determined by measuring the variation in the photopeak amplitude as a function of bias voltage at a given photon energy using a pulse-height analyzer. The $({\mu}{\tau})_e$ values were found to be $(9.6{\pm}1.4){\times}10^{-3}cm^2V^{-1}$ for $1000mm^3$, $(8.4{\pm}1.6){\times}10^{-3}cm^2V^{-1}$ for $1687.5mm^3$ and $(7.6{\pm}1.1){\times}10^{-3}cm^2V^{-1}$ for $2250mm^3$ CdZnTe detectors. Those results were then compared with the literature $({\mu}{\tau})_e$ values for CdZnTe detectors. The present results indicate that, the electron mobility ${\mu}_e$ and electron $({\mu}{\tau})_e$ values in CdZnTe detectors can be measured easily by applying voltage transients response to low energy photons, utilizing a fast signal acquisition and data reduction and evaluation.

Statistical Thermodynamical Properties and Adsorption Characteristics of Heavy Water (중수의 열역학적 성질과 흡착특성)

  • Chang-Hyun Jho;Hyungsuk Park;Seihun Chang
    • Journal of the Korean Chemical Society
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    • v.15 no.6
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    • pp.285-293
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    • 1971
  • The statistical thermodynamical properties of heavy water are calculated according to the transient state theory of significant liquid structure. The calculated values are shown to be in good agreement with the observed ones. The grand canonical ensemble partition function for the adsorbed phase of heavy water on graphite surface is derived using the theory. The adsorption isotherm, the surface pressure, the molar entropy and the molar internal energy for the adsorbed phase and then the molar heat of adsorption are calculated according to the derived partition function. The thermodynamic properties of the adsorbed water are also calculated and the results are compared with those of heavy water and discussed in view of the experimentally observed phenomena.

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A Practical Stability Control Strategy for DC/DC Converters

  • Jiang, Lin;Li, Po
    • Journal of Electrical Engineering and Technology
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    • v.13 no.3
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    • pp.1232-1240
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    • 2018
  • This paper aims at designing an intelligent controller, based on control Lyapunov Function strategy integrated with fabricating discrete model of Buck and Boost converters and analyzing energy changes during the DC/DC progress to realize tracing reference current on Buck and Boost converters. In addition, practical stability phenomenon research and transient performance analysis has been proposed to give an insight to the influence of controller parameters in achieving an enhanced output performance and how the time of sample period affect the error of practical stability will be illustrated. The novelty of this controller in comparison to other schemes lies in the improved performance of practical stability.

Influence of the Effective Thermal Thansport Length on the Heat Transfer Characteristics of a Liquid-Metal Heat Pipe for High-temperature Solar Thermal Devices (유효열이송거리가 고온 태양열기기용 액체금속 히트파이프의 열전달 특성에 미치는 영향)

  • Park, Cheol-Min;Boo, Joon-Hong;Kim, Jin-Soo;Kang, Yong-Heack
    • 한국태양에너지학회:학술대회논문집
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    • 2008.11a
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    • pp.220-225
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    • 2008
  • Cylindrical stainless-steel/sodium heat pipe for a high-temperature solar thermal application was manufactured and tested for transient and steady-state operations. Two layers of stainless-steel screen mesh wick was inserted as a capillary structure. The outer diameter of the heat pipe was 12.7 mm and the total length was 250 mm. The effective heat transport length, the thermal load, and the operating temperature were varied as thermal transport conditions of the heat pipe. The thermal load was supplied by an electric furnace up to 1kW and the cooling was performed by forced convection of air The effective thermal conductivity and the thermal resistance were investigated as a function of heat flux, heat transport length, and vapor temperature. Typical range of the total effective thermal conductivity was as low as 43,500 W/m K for heat flux of 176.4 kW/$m^2$ and of operating temperature of 1000 K.

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Dynamic ATC Computation for Real-Time Power Markets

  • Venkaiah, Ch.;Kumar, D.M. Vinod;Murali, K.
    • Journal of Electrical Engineering and Technology
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    • v.5 no.2
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    • pp.209-219
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    • 2010
  • In this paper, a novel dynamic available transfer capability (DATC) has been computed for real time applications using three different intelligent techniques viz. i) back propagation algorithm (BPA), ii) radial basis function (RBF), and iii) adaptive neuro fuzzy inference system (ANFIS) for the first time. The conventional method of DATC is tedious and time consuming. DATC is concerned with calculating the maximum increase in point to point transfer such that the transient response remains stable and viable. The ATC information is to be continuously updated in real time and made available to market participants through an internet based Open Access Same time Information System (OASIS). The independent system operator (ISO) evaluates the transaction in real time on the basis of DATC information. The dynamic contingency screening method [1] has been utilized and critical contingencies are selected for the computation of DATC using the energy function based potential energy boundary surface (PEBS) method. The PEBS based DATC has been utilized to generate patterns for the intelligent techniques. The three different intelligent methods are tested on New England 68-bus 16 machine and 39-bus 10 machine systems and results are compared with the conventional PEBS method.

Alarm Diagnosis of RCP Monitoring System using Self Dynamic Neural Networks (자기 동적 신경망을 이용한 RCP 감시 시스템의 경보진단)

  • Yu, Dong-Wan;Kim, Dong-Hun;Seong, Seung-Hwan;Gu, In-Su;Park, Seong-Uk;Seo, Bo-Hyeok
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.49 no.9
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    • pp.512-519
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    • 2000
  • A Neural networks has been used for a expert system and fault diagnosis system. It is possible to nonlinear function mapping and parallel processing. Therefore It has been developing for a Diagnosis system of nuclear plower plant. In general Neural Networks is a static mapping but Dynamic Neural Network(DNN) is dynamic mapping.쪼두 a fault occur in system a state of system is changed with transient state. Because of a previous state signal is considered as a information DNN is better suited for diagnosis systems than static neural network. But a DNN has many weights so a real time implementation of diagnosis system is in need of a rapid network architecture. This paper presents a algorithm for RCP monitoring Alarm diagnosis system using Self Dynamic Neural Network(SDNN). SDNN has considerably fewer weights than a general DNN. Since there is no interlink among the hidden layer. The effectiveness of Alarm diagnosis system using the proposed algorithm is demonstrated by applying to RCP monitoring in Nuclear power plant.

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Study on InGaAs/InGaAsP/InP Quantum-dot Molecules for Quantum Interference devices (양자간섭소자를 위한 InGaAs/InGaAsP/InP 양자점 분자구조 연구)

  • Kim Jin-Soak;Kim Eun-Kyu;Jeong Weon-G.
    • Journal of the Korean Vacuum Society
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    • v.15 no.2
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    • pp.186-193
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    • 2006
  • In this study, we analyzed the electrical and optical properties of metalorganic chemical vapor deposition grown InGaAs/InGaAsP/InP quantum dot(QD) molecules by using photoluminescence and deep-level transient spectroscopy. From these resulte, the energy levels of the large QDs are located at deeper region from the conduction band edge of the barrier than that of the small QDs, The large QDs seem to have the energy states more than two, and these energy levels of the QD molecules are located at 0.35, 0.42, and 0.45 eV from conduction band edge under -4 V reverse bias conditions. The energy levels are closely coupled under low reverse bias, and then decoupled as the bias voltage is increased.

A three-region movable-boundary helical coil once-through steam generator model for dynamic simulation and controller design

  • Shifa Wu;Zehua Li;Pengfei Wang;G.H. Su;Jiashuang Wan
    • Nuclear Engineering and Technology
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    • v.55 no.2
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    • pp.460-474
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    • 2023
  • A simple but accurate mathematical model is crucial for dynamic simulations and controller design of helical coil once-through steam generator (OTSG). This paper presents a three-region movable boundary dynamic model of the helical coil OTSG. Based on the secondary side fluid conditions, the OTSG is divided into subcooled region (two control volumes), two-phase region (two control volumes) and superheated region (three control volumes) with movable boiling boundaries between each region. The nonlinear dynamic model is derived based on mass, energy and momentum conservation equations. And the linear model is obtained by using the transfer function and state space transformation, which is a 37-order model of five input and three output. Validations are made under full-power steady-state condition and four transient conditions. Results show good agreements among the nonlinear model, linear model and the RELAP5 model, with acceptable errors. This model can be applied to dynamic simulations and controller design of helical coil OTSG with constant primary-side flow rate.

Single Line-to-ground Fault Location and Information Modeling Based on the Interaction between Intelligent Distribution Equipment

  • Wang, Lei;Luo, Wei;Weng, Liangjie;Hu, Yongbo;Li, Bing
    • Journal of Electrical Engineering and Technology
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    • v.13 no.5
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    • pp.1807-1813
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    • 2018
  • In this paper, the fault line selection and location problems of single line-to-ground (SLG) fault in distribution network are addressed. Firstly, the adaptive filtering property for empirical mode decomposition is formulated. Then in view of the different characteristics showed by the intrinsic mode functions(IMF) under different fault inception angles obtained by empirical mode decomposition, the sign of peak value about the low-frequency IMF and the capacitance transient energy is chosen as the fault line selection criteria according to the different proportion occupied by the low-frequency components. Finally, the fault location is determined based upon the comparison result with adjacent fault passage indicators' (FPI) waveform on the strength of the interaction between the distribution terminal unit(DTU) and the FPI. Moreover, the logic nodes regarding to fault line selection and location are newly expanded according to IEC61850, which also provides reference to acquaint the DTU or FPI's function and monitoring. The simulation results validate the effectiveness of the proposed fault line selection and location methods.

Finite Control Set Model Predictive Control of AC/DC Matrix Converter for Grid-Connected Battery Energy Storage Application

  • Feng, Bo;Lin, Hua
    • Journal of Power Electronics
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    • v.15 no.4
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    • pp.1006-1017
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    • 2015
  • This paper presents a finite control set model predictive control (FCS-MPC) strategy for the AC/DC matrix converter used in grid-connected battery energy storage system (BESS). First, to control the grid current properly, the DC current is also included in the cost function because of input and output direct coupling. The DC current reference is generated based on the dynamic relationship of the two currents, so the grid current gains improved transient state performance. Furthermore, the steady state error is reduced by adding a closed-loop. Second, a Luenberger observer is adopted to detect the AC input voltage instead of sensors, so the cost is reduced and the reliability can be enhanced. Third, a switching state pre-selection method that only needs to evaluate half of the active switching states is presented, with the advantages of shorter calculation time, no high dv/dt at the DC terminal, and less switching loss. The robustness under grid voltage distortion and parameter sensibility are discussed as well. Simulation and experimental results confirm the good performance of the proposed scheme for battery charging and discharging control.