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A learning framework based on weighted knowledge transfer for holiday load forecasting

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Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 329-339页

作者： Pan ZENG Chang SHENG min jin College of Computer Science and Electronic Engineering Hunan University

Since the variation pattern of load during holidays is different than that of non-holidays, forecasting holiday load is a challenging task. With a focus on this problem, we propose a learning framework based on weighted knowledge transfer for daily peak load forecasting during ***,we select source cities which can provide extra hidden knowledge to improve the forecast accuracy of the load of the target city. Then, all the instances which are from source cities and the target city will be weighted and trained by the improved weighted transfer learning algorithm which is based on the TrAdaBoost algorithm and can decrease negative transfer. We evaluate our method with the classical support vector machine method and a method based on knowledge transfer on a real data set, which includes eleven cities in Guangdong province of China,to illustrate the performance of the method. To solve the problem of limited historical holiday load data, we transfer the data from nearby cities based on the fact that nearby cities in Guangdong province of China have a similar economic development level and similar load variation pattern. The results of comparative experiments show that the framework proposed by this paper outperforms these methods in terms of mean absolute percent error and mean absolute scaled error.

关键词： Load forecasting Holiday effect Sparse data Weighted knowledge transfer

Partitioning Complete Graphs by Heterochromatic Trees

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Acta Mathematicae Applicatae Sinica 2012年第4期28卷 625-630页

作者： Ze-min jin Xue-liang LI Department of Mathematics Zhejiang Normal University Center for Combinatorics and LPMC Nankai University

A heterochromatie tree is an edge-colored tree in which any two edges have different colors. The heterochromatic tree partition number of an r-edge-colored graph G, denoted by tr （G）, is the minimum positive integer p such that whenever the edges of the graph G are colored with r colors, the vertices of G can be covered by at most p vertex-disjoint heterochromatic trees. In this paper we determine the heterochromatic tree partition number of r-edge-colored complete graphs. We also find at most tr（Kn） vertex-disjoint heterochromatic trees to cover all the vertices in polynomial time for a given r-edge-coloring of Kn.

关键词： edge-colored graph heterochromatic tree partition

Analysis of a new 5-phase bearingless induction motor

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第8期8卷 1311-1319页

作者： HUANG jin KANG min YANG Jia-qiang School of Electrical Engineering Zhejiang University Hangzhou 310027 China

This paper addresses the bearingless motor with a single set of multiphase windings. The interaction between M and M±1 pole-pair magnetic fields produces radial force. Based on this principle,a bearingless machine is obtained. Conventional bearingless machine has dual windings,levitation windings and torque windings,which produce the two magnetic fields. In the proposed bearingless motor,the two needed magnetic fields are produced by feeding two groups of currents to a single set of multiphase windings. Taking a 5-phase induction motor as example,the inductance matrices,considering air gap eccentricity,are calculated with the modified winding function method. The radial force analytical model is deduced by virtual displacement,and its results are validated by FEA. The mathematical model of the new bearingless machine is set up,and the simulation results verified the feasibility of this novel bearingless motor.

关键词： Air-gap-flux-oriented control Bearingless motor Multiphase Radial force Single set of windings Modified winding function method

Vertex partitions of r-edge-colored graphs

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Applied Mathematics(A Journal of Chinese Universities) 2008年第1期23卷 120-126页

作者： jin Ze-min LI Xue-liang Center for Combinatorics and LPMC-TJKLC Nankai University Tianjin 300071 China. Department of Mathematics Zhejiang Normal University Jinhua 321004 China.

Let G be an edge-colored graph. The monochromatic tree partition problem is to find the minimum number of vertex disjoint monochromatic trees to cover the all vertices of G. In the authors＇ previous work, it has been proved that the problem is NP-complete and there does not exist any constant factor approximation algorithm for it unless P= NP. In this paper the authors show that for any fixed integer r ≥ 5, if the edges of a graph G are colored by r colors, called an r-edge-colored graph, the problem remains NP-complete. Similar result holds for the monochromatic path （cycle） partition problem. Therefore, to find some classes of interesting graphs for which the problem can be solved in polynomial time seems interesting. A linear time algorithm for the monochromatic path partition problem for edge-colored trees is given.

关键词： monochromatic tree (path cycle) NP-complete linear time algorithm.

Two-Higgs-doublet models in light of current experiments:a brief review

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Communications in Theoretical Physics 2022年第9期74卷 235-256页

作者： Lei Wang jin min Yang Yang Zhang Department of Physics Yantai UniversityYantai 264005China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Science University of Chinese Academy of SciencesBeijing 100049China School of Physics and Microelectronics Zhengzhou UniversityZhengZhou 450001China

We briefly survey several typical CP-conserving two-Higgs-doublet models(2HDMs)in light of current *** we derive the masses and couplings of the mass eigenstates from the *** we analyze the constraints from theory and oblique electroweak ***,we delineate the status of 2HDM in light of the LHC searches,the dark matter detections and the muon g-2 measurement.

关键词： two-Higgs-doublet model LHC dark matter muon anomalous magnetic moment

Quantum gradient descent algorithms for nonequilibrium steady states and linear algebraic systems

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Science China(Physics,Mechanics & Astronomy) 2022年第5期65卷 21-33页

作者： jin-min Liang Shi-Jie Wei Shao-ming Fei School of Mathematical Sciences Capital Normal UniversityBeijing J00048China Beijing Academy of Quantum Information Sciences Beijing 100193China State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics Tsinghua UniversityBeijing 100084China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China

The gradient descent approach is the key ingredient in variational quantum algorithms and machine learning tasks,which is an optimization algorithm for finding a local minimum of an objective *** quantum versions of gradient descent have been investigated and implemented in calculating molecular ground states and optimizing polynomial *** on the quantum gradient descent algorithm and Choi-Jamiolkowski isomorphism,we present approaches to simulate efficiently the nonequilibrium steady states of Markovian open quantum many-body *** strategies are developed to evaluate the expectation values of physical observables on the nonequilibrium steady ***,we adapt the quantum gradient descent algorithm to solve linear algebra problems including linear systems of equations and matrix-vector multiplications,by converting these algebraic problems into the simulations of closed quantum systems with well-defined *** examples are given to test numerically the effectiveness of the proposed algorithms for the dissipative quantum transverse Ising models and matrix-vector multiplications.

关键词： quantum simulation quantum gradient descent algorithm nonequilibrium steady state quantum open system

Emission inventory evaluation using observations of regional atmospheric background stations of China

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Journal of Environmental Sciences 2013年第3期25卷 537-546页

作者： Xingqin An Zhaobin Sun Weili Lin min jin Nan Li Chinese Academy of Meteorological Sciences China Meteorological Administration Beijing Meteorological Observatory

Any accurate simulation of regional air quality by numerical models entails accurate and up-to-date emissions data for that *** INTEX-B2006 （I06）,one of the newest emission inventories recently popularly used in China and East Asia,has been assessed using the Community Multiscale Air Quality model and observations from regional atmospheric background stations of *** of the model results with the observations for the species SO2,NO 2,O 3 and CO from the three regional atmospheric background stations of Shangdianzi,Longfengshan and Linan show that the model can basically capture the temporal characteristics of observations such as the monthly,seasonal and diurnal variance *** to the other three species,the simulated CO values were grossly underestimated by about two-third or one-half of the observed values,related to the uncertainty in CO *** to the other two stations,Shangdianzi had poorer simulations,especially for SO2 and CO,which partly resulted from the site location close to local emission sources from the Beijing area;and the regional inventory used was not capable of capturing the influencing factors of strong regional sources on ***,the fact that summer gave poor simulation,especially for SO2 and O 3,might partly relate to poor simulations of meteorological fields such as temperature and wind.

关键词： evaluation CMAQ model INTEX-B2006 inventory regional atmospheric background stations

Development of polyimide films reinforced with boron nitride and boron nitride nanosheets for transparent flexible device applications

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Nano Research 2018年第5期11卷 2366-2378页

作者： You jin min Kyeong-Hee Kang Dae-Eun Kim Department of Mechanical Engineering Yonsei University 50 Yonsei-ro Seodaemun-gu Seoul 03722 Republic of Korea

The benefits of reinforcing polyimide （PI） films with boron nitride （BN） particles and boron nitride nanosheets （BNNSs） were assessed with the aim of enhancing their thermal, optical, and mechanical properties for flexible device applications. BNNSs were prepared from BN particles using a liquid-phase exfoliation method assisted by an ultrasonic probe-type sonicator and centrifugator. PI-based composite films blended with BNNSs and BN particles were fabricated at various concentrations via mechanical stirring and spin coating. The transparency of the PI/BNNS composite films remained almost the same as that of pure PI films up to 3 wt.% whereas the transparency of the PI/BN composite films decreased with increasing concentration of the BN fillers at 550 nm. The thermal stability improved significantly with increasing concentrations of both BN and BNNS relative to that of pure PI films. The temperature for 5% weight loss of the PI/BNNS composite film was higher than that of the PI/BN composite film at the same filler concentration. The composite films with 2 wt.% BN or BNNS showed the lowest wear rate, and the PI/BNNS composite films showed more stable frictional behavior compared to the PI/BN composite films. In addition, bending tests showed that the PI/BNNS composite films exhibited excellent flexibility compared to the PI/BN composite films. Overall, the results indicate that the BNNS can be effectively used as a filler that can enhance the thermal and mechanical properties of polymer materials for flexible device applications.

关键词： polyimide (PI) boron nitride (BN) transparency thermal properties flexibility tribology

Emission-tunable Ba_(2)Y_(1-x)Sc_(x)NbO_(6):Bi^(3+)(0≤x≤1.0)phosphors for white LEDs

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Journal of Rare Earths 2022年第12期40卷 1819-1826,I0001页

作者： Zhihua Gao Fengyan Fu Lili Niu min jin Xiaohong Wang Department of Applied Chemistry Hengshui UniversityHengshui 053000China Sichuan University Chengdu 610041China

Here,we report a series of Bi^(3+)-doped Ba_(2)Y_(1-x)Sc_(x)NbO_(6)(0≤x≤1.0 mol)phosphors by using the traditional high temperature solid-state *** achieve the structural and photoluminescent(PL)information,several experimental characterizations and theoretical calculations were carried out,including X-ray diffraction(XRD),Rietveld refinement,UV-visible diffuse reflectance and PL spectra,temperature dependent PL spectra,and density functional theo retical(DFT)*** XRD results show that the Bi^(3+)-doped Ba_(2)Y_(1-x)Sc_(x)NbO_(6)samples belong to the double-perovskite phase with a cubic space group of Fm3 m,and the diffraction positions shift toward high diffraction angle when the larger Y^(3+)ions are gradually replaced by the smaller Sc^(3+)*** addition,the refined XRD findings show that the Bi^(3+)ions tend to substitute the Y^(3+)and Sc^(3+)sites in the Bi^(3+)-doped Ba_(2)Y_(1-x)Sc_(x)NbO_(6)0minated by a resonant type via a dipole-quadrupole(d-q)*** Ba_(2)Y_(0.6)Sc_(0.4)NbO_(6):0.02 molBi^(3+)shows the strongest PL intensity under 365 nm excitation,with the best quantum efficiency(QE)of 68%,and it keeps 60%of the room temperature emission intensity when the temperature increases to 150℃,meaning that the Ba_(2)Y_(0.6)Sc_(0.4)NbO_(6):Bi^(3+)features excellent thermal quenching of *** combining this optimal sample with a commercial red-emitting Sr_(2)Si_(5)N_(8):Eu^(2+)phosphor,and a commercial 365 nm UV LED chip,a white LED device,with the color temperature(CT)of 3678 K,color rendering index(CRI)of 67.9,and CIE coordinates at(0.371,0.376),is achieved.

关键词： Bi^(3+) Double-perovskite Tunable emission Energy transfer White LEDs Rare earths