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INTEGRAL-TYPE TESTS FOR GOODNESS-OF-FIT

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Journal of Systems Science & Complexity 2010年第4期23卷 784-795页

作者： junjian ZHANG Guoying LI College of Mathematics Guangxi Normal University Guilin 541004 China College of Applied Sciences Beijing University of Technology Beijing 100124 China Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China

A family of integral-type goodness-of-fit tests is investigated. This family includes some existing tests, such as the Cramer-von Mises test and Anderson-Darling test, etc. The asymptotic distributions of the tests in the family under the null and local alternative hypotheses are established. The almost sure convergence under a fixed underlying distribution is obtained. Furthermore, simulations are conducted to compare the powers of the tests in the family. Simulation results show that for different alternatives, the more powerful tests are different, and the parameter ）, has great influence on the tests in small sample cases.

关键词： Asymptotic distribution goodness-of-fit integral-type tests power comparison.

Resilience Analysis and Cascading Failure Modeling of Power Systems Under Extreme Temperatures

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Journal of Modern Power Systems and Clean Energy 2021年第6期9卷 1446-1457页

作者： Seyyed Rashid Khazeiynasab junjian Qi IEEE Department of Electrical and Computer Engineering University of Central Florida

In this paper, we propose an AC power flow based cascading failure model that explicitly considers external weather conditions, extreme temperatures in particular, and evaluates the impact of extreme temperature on the initiation and propagation of cascading blackouts. Based on this model, resilience analysis of the power system is performed with extreme temperatures. Specifically, the changes of load and dynamic line rating are modeled due to temperature disturbance. The probabilities for transmission line and generator outages are evaluated, and the timing for each type of events is calculated to decide the actual event sequence. It should be emphasized that the correlated events, in the advent of external temperature changes, could contribute to voltage instability. Besides, we model undervoltage load shedding and operator re-dispatch as control strategies for preventing the propagation of cascading failures. The effectiveness of the proposed model is verified by simulation results on the RTS-96 3-area system. It is found that temperature disturbances can lead to correlated load change and line/generator tripping, which will greatly increase the risk of cascading and voltage instability. Critical temperature change, critical area with temperature disturbance, the identification of most vulnerable buses, and the comparison of different control strategies are also investigated.

关键词： Blackout cascading failure correlation extreme temperature extreme weather power transmission reliability resilience voltage stability

Data-driven Power Flow Method Based on Exact Linear Regression Equations

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Journal of Modern Power Systems and Clean Energy 2022年第3期10卷 800-804页

作者： Yanbo Chen Chao Wu junjian Qi State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources School of Electrical&Electronic EngineeringNorth China Electric Power UniversityBeijing 102206China Department of Electrical and Computer Engineering Stevens Institute of TechnologyHobokenNJ 07030USA

Power flow(PF)is one of the most important calculations in power *** widely-used PF methods are the Newton-Raphson PF(NRPF)method and the fast-decoupled PF(FDPF)*** smart grids,power generations and loads become intermittent and much more uncertain,and the topology also changes more frequently,which may result in significant state shifts and further make NRPF or FDPF difficult to *** address this problem,we propose a data-driven PF(DDPF)method based on historical/simulated data that includes an offline learning stage and an online computing *** the offline learning stage,a learning model is constructed based on the proposed exact linear regression equations,and then the proposed learning model is solved by the ridge regression(RR)method to suppress the effect of data *** online computing stage,the nonlinear iterative calculation is not *** results demonstrate that the proposed DDPF method has no convergence problem and has much higher calculation efficiency than NRPF or FDPF while ensuring similar calculation accuracy.

关键词： Data driven exact linear regression equation Fast-decoupled power flow Newton-Raphson method

Efficient visible light photo-Fenton-like degradation of organic pollutants using in situ surface-modified BiFeO_3 as a catalyst

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Journal of Environmental Sciences 2013年第6期25卷 1213-1225页

作者： junjian an Lihua Zhu Yingying Zhang Heqing Tang College of Chemistry and Chemical Engineering Huazhong University of Science and Technology Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission and Ministry of Education College of Chemistry and Materials ScienceSouth-Central University for Nationalities

The visible light photo-Fenton-like catalytic performance of BiFeO3 nanoparticles was investigated using Methyl Violet （MV）, Rhodamine B （RhB） and phenol as probes. Under optimum conditions, the pseudo first-order rate constant （k） was determined to be 2.21 × 10^-2, 5.56 × 10^-2 and 2.01 × 10^-2 min〈 for the degradation of MV （30 μmol/L）, RhB （10 μmol/L） and phenol （3 mmol/L）, respectively, in the BiFeO3-H202-visible light （Vis） system. The introduction of visible light irradiation increased the k values of MV, RhB and phenol degradation 3.47, 1.95 and 2.07 times in comparison with those in dark. Generally, the k values in the BiFeO3- H202-Vis system were accelerated by increasing BiFeO3 load and H202 concentration, but decreased with increasing initial pollutant concentration. To further enhance the degradation of pollutants at high concentrations, BiFeO3 was modified with the addition of surface modifiers. The addition of ethylenediamineteraacetic acid （EDTA, 0.4 mmol/L） increased the k value of MV degradation （60 μmol/L） from 1.01 × 10.2 min^-1 in the BiFeO3-H202-Vis system to 1.30 min^-1 in the EDTA-BiFeO3-H2O2-Vis system by a factor of 128. This suggests that in situ surface modification can enable BiFeO3 nano-particles to be a promising visible light photo-Fenton-like catalyst for the degradation of organic pollutants.

关键词： nanoscale BiFeO3 visible light photo-Fenton-like catalysis degradation surface modification

Removing lignin model pollutants with BiFeO_3–g-C_3N_4 compound as an efficient visible-light-heterogeneous Fenton-like catalyst

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Journal of Environmental Sciences 2016年第10期28卷 218-229页

作者： junjian an Guangyan Zhang Rongfeng Zheng Peng Wang School of Pulp and Paper Engineering Hubei Provincial Key Laboratory of Green Materials for Light Industry Hubei University of Technology

BiFeO3-g-C3N4 nanoscaled composite was prepared with a hydrothermal method and evaluated as a highly efficient photo-Fenton like catalyst under visible light irradiation. The BiFeO3-g-CHN4 composite exhibited much stronger adsorption ability to lignin model pollutant （guaiacol） than that of BiFeO3, which may be due to the higher specific surface area （BiFeO3-g-C3N4：35.59 m2/g 〉 BiFeO3：7.42 m2/g） and the adsorption form of π-π stack between g-C3N4 and guaiacol. The composite exhibited excellent visible light-Fenton like catalysis activity, being influenced by the solution pH value and the proportions of BiFe03 and g-C3N4 nanosheets. Under optimal conditions with visible light irradiation, the BiFeO3- g-C3N4 composite yielded fast degradation of guaiacol with an apparent rate constant of 0.0452 rain-I, which were 5.21 and 6.80 folds of that achieved by using BiFeO3 and the mixture of BiFeO3 and g-C3N4 nanosheets, respectively. The significantly enhanced visible light-Fenton like catalytic properties of the BiFeO3-g-C3N4 composite in comparison with that of BiFeO3 was attributed to a large surface area, much increased adsorption capacity and the semiconductor coupling effect between BiFe03 and g-C3N4 in the composite.

关键词： BiFeO3g-C3N4 nanosheetsHeterogeneous Fenton-like catalysisVisible light catalystDegradation

Soil Polycyclic Aromatic Hydrocarbons Across Urban Density Zones in Shenzhen, China: Occurrences, Source Apportionments,and Spatial Risk Assessment

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Pedosphere 2016年第5期26卷 676-686页

作者： ZHANG Di WANG junjian ZENG Hui College of Urban and Environmental Sciences Peking University Shenzhen Key Laboratory of Circular Economy Shenzhen Graduate School Peking University The Belle W.Baruch Institute of Coastal Ecology & Forest Science Clemson University

Urbanization may cause increased exposure levels to polycyclic aromatic hydrocarbons （PAHs） and associated health risks for over half of the world＇s population living in cities, but little evidence has shown a direct spatial relationship between urbanization and soil PAH pollution. Based on the monitored PAH concentrations in 188 topsoil （0-5 cm） samples in Shenzhen, the most rapidly developing city in China, in recent decades, we applied geographical demarcation to determine the occurrences, source apportionments, and spatial ecological risks of soil PAHs across five zones of varying urban densities. Mean concentrations of the 16 US Environmental Protection Agency （EPA） priority PAHs （∑16PAHs） and the 7 carcinogenic PAHs （2E7CarPAHs） both followed the order： Zone D （60%-80% constructive land density （CLD））〉 Zone E （80%-100% CLD）〉 Zone C （40%-60% CLD）〉 Zone B （20%-40% CLD）〉 Zone A （0%-20% CLD）, suggesting that the highest PAH levels occurred in the suburban-urban center transitional zone （Zone D） rather than the urban center zone （Zone E） in Shenzhen. There were significant correlations of ∑16PAHs to TOC and sampling altitude across all samples but not within highly-urbanized regions （Zones D and E）, implying a considerable disturbance of urbanization to the soil PAH pool. Source apportionments suggested that soil PAHs of all zones were mainly derived from fossil fuel combustion, with Zone E showing the highest contribution from oil sources among different zones. Spatial ecological risk analysis showed that the contaminated area （467 km2; 23.9% of total area; toxic equivalency quotients 〉 33 ng g^-1） had a higher contribution from the highly-urbanized regions （Zones D and E） than the uncontaminated area （42.3% vs. 18.1%）. Overall, our study highlighted a strong spatial relationship between urbanization and soil PAH pollution.

关键词： altitude carcinogenic PAHs soil PAH pollution total organic C toxic equivalency quotient urbanization US EPA priority PAH

SUMMATION OF ABSOLUTE VALUE TEST FOR MULTIPLE OUTCOME COMPARISON WITH MODERATE EFFECT

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Journal of Systems Science & Complexity 2013年第3期26卷 462-469页

作者： LI Zhengbang CAO Fan ZHANG junjian LI Qizhai School of Mathematics and Statistics Wuhan University Guangxi Normal University Academy of Mathematics and Systems Science Chinese Academy of Sciences

In biomedical research,in order to evaluate the effect of a drug,investigators often need to compare the differences between one treatment group and another one by using multiple *** rank-sum tests can handle the case where the outcome differences between two groups are in the same *** they are not,MAX can handle it and is very useful when one/some of the differences is/are relatively larger than the *** the individual outcome difference between two groups is moderate,a new method,summation of the absolute value of rank-based test for each outcome,is proposed in this *** comparison with the existing methods based on simulation studies and a real example show that the proposed test is a robust test,and works well when the difference for each outcome is *** authors also derive some theoretical results for comparing the power between MAX and the the proposed method.

关键词： Absolute value generalized inverse multiple outcomes rank-sum test

Recurrent Neural Network for Nonconvex Economic Emission Dispatch

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Journal of Modern Power Systems and Clean Energy 2021年第1期9卷 46-55页

作者： Jiayu Wang Xing He junjian Huang Guo Chen Chongqing Key Laboratory of Nonlinear Circuits and Intelligent Information Processing College of Electronic and Information EngineeringSouthwest UniversityChongqing 400715China Key Laboratory of Machine Perception and Children's Intelligence Development Chongqing University of EducationChongqing 400067China School of Electrical Engineering and Computer Science University of NewcastleNewcastleNSW 2308Australia

In this paper, an economic emission dispatch(EED) model is developed to reduce fuel cost and environmental pollution emissions. Considering the development of new energy sources in recent years, the EED problem involves thermal units with the valve point effect and WTs. Meanwhile, it complies with demand constraint and generator capacity constraints. A recurrent neural network(RNN) is proposed to search for local optimal solution of the introduced nonconvex EED problem. The optimality and convergence of the proposed dynamic model are given. The RNN algorithm is verified on a power generation system for the optimization of scheduling and minimization of total cost. Moreover, a particle swarm optimization(PSO) algorithm is compared with RNN under the same problematic frame. Numerical simulation results demonstrate that the optimal scheduling given by RNN is more precise and has lower total cost than PSO. In addition, the dynamic variation of power load demand is considered and the power distribution of eight generators during 12 time periods is depicted.

关键词： Recurrent neural network(RNN) nonconvex economic emission dispatch optimization problem

A Closed-form Formulation of Eigenvalue Sensitivity Based on Matrix Calculus for Small-signal Stability Analysis in Power System

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Journal of Modern Power Systems and Clean Energy 2021年第6期9卷 1436-1445页

作者： Peijie Li Yucheng Wei junjian Qi Xiaoqing Bai Hua Wei School of Electrical Engineering Guangxi University Department of Electrical and Computer Engineering Stevens Institute of Technology

With the rapid development of power-electronicsenabled power systems,the new converter-based generators are deteriorating the small-signal stability of the power *** the numerical differentiation method has been widely used for approximately calculating the eigenvalue sensitivities,its accuracy has not been carefully ***,the element-based formulation for computing closed-form eigenvalue sensitivities has not been used in any commercial software due to the average efficiency,complicated formulation,and errorprone *** on the matrix calculus,this paper proposes an easily manipulated formulation of the closed-form eigenvalue sensitivities with respect to the power *** distinguishing feature of the formulation is that all the formulas consist of vector and matrix operations,which can be performed by developed numerical algorithms to take full advantages of architectural features of the modern *** tests on WSCC 3-machine 9-bus system,New England 10-machine 39-bus system,and IEEE 54-machine 118-bus system show that the accuracy of the proposed formulation is superior to the numerical differentiation method and the efficiency is also greatly improved compared to the element-based closed-form *** proposed formulation will be helpful to perform a more accurate and faster stability analysis of a power grid with converter-based devices.

关键词： Closed-form formulation converter-based devices eigenvalue sensitivity matrix calculus small-signal stability