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Xia, Bin,Ren, Ziyan,Koh, Chang Seop IEEE 2017 IEEE transactions on magnetics Vol.53 No.6
<P>This paper proposes an efficient reliability-based optimization algorithm based on adaptive dynamic Taylor Kriging (ADTK). In the ADTK model, the basis functions are optimally selected by the binary particle swarm optimization algorithm and the minimal number of sampling data with a desired fitting error is decided. To evaluate performance of reliability calculation, the Monte Carlo simulation method is employed, where the performance constraint functions are constructed by the ADTK surrogate model. Overall, an electromagnetic application-superconducting magnetic energy storage device (TEAM problem 22) is used to investigate performances of the proposed method.</P>
Ren, Zhouyang,Yan, Wei,Zhao, Xia,Zhao, Xueqian,Yu, Juan The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.2
This paper presents a probabilistic power flow (PPF) analysis method for distribution network incorporating the randomness and correlation of photovoltaic (PV) generation. Based on the multivariate kernel density estimation theory, the probabilistic model of PV generation is proposed without any assumption of theoretical parametric distribution, which can accurately capture not only the randomness but also the correlation of PV resources at adjacent locations. The PPF method is developed by combining the proposed PV model and Monte Carlo technique to evaluate the influence of the randomness and correlation of PV generation on the performance of distribution networks. The historical power output data of three neighboring PV generators in Oregon, USA, and 34-bus/69-bus radial distribution networks are used to demonstrate the correctness, effectiveness, and application of the proposed PV model and PPF method.
Xia, Bin,Ren, Ziyan,Zhang, Yanli,Koh, Chang-Seop The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.5
In this paper, an adaptive optimization strategy utilizing Kriging model and genetic algorithm is proposed for the optimal design of electromagnetic devices. The ordinary Kriging assisted by the spherical covariance model is used to construct surrogate models. In order to improve the computational efficiency, the adaptive uniform sampling strategy is applied to generate sampling points in design space. Through several iterations and gradual refinement process, the global optimal point can be found by genetic algorithm. The proposed algorithm is validated by application to the optimal design of a switched reluctance motor, where the stator pole face and shape of pole shoe attached to the lateral face of the rotor pole are optimized to reduce the torque ripple.
The simulation study on natural circulation operating characteristics of FNPP in inclined condition
Ren Li,Genglei Xia,Minjun Peng,Lin Sun 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.7
Previous research has shown that the inclined condition has an impact on the natural circulation (natural circulation) mode operation of Floating Nuclear Power Plant (FNPP) mounted on the movable marine platform. Due to its compact structure, small volume, strong maneuverability, the Integral Pressurized Water Reactor (IPWR) is adopted as marine reactor in general. The OTSGs of IPWR are symmetrically arranged in the annular region between the reactor vessel and core support barrel in this paper. Therefore, many parallel natural circulation loops are built between the core and the OTSGs primary side when the main pump is stopped. and the inclined condition would lead to discrepancies of the natural circulation drive head among the OTSGs in different locations. In addition, the flow rate and temperature nonuniform distribution of the core caused by inclined condition are coupled with the thermal hydraulics parameters maldistribution caused by OTSG group operating mode on low power operation. By means of the RELAP5 codes were modified by adding module calculating the effect of inclined, heaving and rolling condition, the simulation model of IPWR in inclined condition was built. Using the models developed, the influences on natural circulation operation by inclined angle and OTSG position, the transitions between forced circulation (forced circulation) and natural circulation and the effect on natural circulation operation by different OTSG grouping situations in inclined condition were analyzed. It was observed that a larger inclined angle results the temperature of the core outlet is too high and the OTSG superheat steam is insufficient in natural circulation mode operation. In general, the inclined angle is smaller unless the hull is destroyed seriously or the platform overturn in the ocean. In consequence, the results indicated that the IPWR in the movable marine platform in natural circulation mode operation is safety. Selecting an appropriate average temperature setting value or operating the uplifted OTSG group individually is able to reduce the influence on natural circulation flow of IPWR by inclined condition.
A Correlation Evaluation Method of PV Power Output Based on ITOPSIS
Xia Weiyi,Ren Zhouyang,Li Hui,Song Yue,Hu Xiuqiong,Hu Bo 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.4
Based on the Improved Technique for Order Preference by Similarity to an Ideal Solution (ITOPSIS), an evaluation method is proposed to quantify the contribution of each photovoltaic (PV) plant on the randomness and sequential characteristics of regional PV power. It can provide valuable information for the operators and planners of power systems, as well as the dealers in electricity market. First, a correlation index system is constructed to evaluate the correlation between the power outputs of individual PV plants and the regional PV power. Next, ITOPSIS is proposed to synthesize the proposed indices. Group standardization and theoretical optimal value avert the decrease of diff erence between plants and make the results applicable for comparing correlations in diff erent cluster. The historical data collected from 16 PV plants were used to verify the eff ectiveness and correctness of the proposed method
Ren, Zhao-Jun,Li, Xiu-Juan,Xu, Xin-Yu,Xia, Lei,Tang, Jin-Hai Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.12
A compariosn was made of survival outcomes of oncoplastic breast conserving therapy (oBCT) with nipple-areolar (NAC) preservation in women with centrally located breast cancer (CLBC) undergoing modified radical mastectomy (MRM) in China in a matched retrospective cohort study. We used a database including patients who received oBCT (n=91) or MRM (n=182) from 2003 to 2013 in our hospital. Matching was conducted according to five variables: age at diagnosis, axillary lymph node status, hormone receptor status, human epidermal growth factor-like receptor 2 status (HER-2) and tumor stage. The match ratio was 1:2. Median follow-up times for the oBCT and MRM groups were 83 and 81 months, respectively. There were no significant differences in 87-month overall, local, or distant recurrence-free survival between patients with oBCT and MRM (89%vs.90%; 93%vs.95%; 91%vs.92%;). For appropriate breast cancer patients, oBCT for CLBC is oncologically safe, oncoplastic techniques improving cosmetic outcomes.
Ren-dong Ge,Zun-Quan Xia,GuoQiang 한국전산응용수학회 2006 Journal of applied mathematics & informatics Vol.22 No.1-2
A modified BFGS algorithm for solving the unconstrained optimization, whose Hessian matrix at the minimum point of the convex function is of rank defects, is presented in this paper.The main idea of the algorithm is first to add a modified term to the convex function for obtain an equivalent model, then simply the model to get the modified BFGS algorithm. The superlinear convergence property of the algorithm is proved in this paper. To compared with the Tensor algorithms presented by R. B. Schnabel (seing [4],[5]), this method is more efficient for solving singular unconstrained optimization in computing amount and complication.
A Load Identification Method for ICPT System Utilizing Harmonics
Xia, Chen-Yang,Zhu, Wen-Ting,Ma, Nian,Jia, Ren-Hai,Yu, Qiang The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.6
Online identification of load parameters is the premise of establishing a stable and highly-efficient ICPT (Inductive Coupled Power Transfer) system. However, compared with pure resistive load, precise identification of composite load, such as resistor-inductance load and resistance-capacitance load, is more difficult. This paper proposes a method for detecting the composite load parameters of ICPT system utilizing harmonics. In this system, the fundamental and harmonic wave channel are connected to the high frequency inverter jointly. The load parameter values can be obtained by setting the load equation based on the induced voltage of secondary-side network, the fundamental wave current, as well as the third harmonic current effective value received by the secondary-side current via Fourier decomposition. This method can achieve precise identification of all kinds of load types without interfering the normal energy transmission and it can not only increase the output power, but also obtain higher efficiency compared with the fundamental wave channel alone. The experimental results with the full-bridge LCCL-S type voltage-fed ICPT system have shown that this method is accurate and reliable.