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A novel dynamic equivalence method for grid-connected wind farm

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第4期9卷 558-563页

作者： jia-geng QIAO Zong-xiang LU Yong MIN State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China

Dynamic equivalence of the wind farm is a fundamental problem in the simulation of a power system connected with wind farms because it is unpractical to model every generator in a wind farm in detail. In this paper, an Equivalence Method based on the Output Characteristics (EMOC) is proposed, with which the wind farm composed of Squirrel-Cage Induction Generators (SCIGs) can be equivalent to one generator. By considering the diversity of wind generators and special operating characteristics of a wind farm, the equivalent generator based on EMOC responds accurately in various faults. No matter whether the wind farm is integrated in grid or just programmed, EMOC can be used to acquire an accurate equivalent generator. Simulation of the dynamic equivalence of an SCIG wind farm validated the method.

关键词： Grid-connected wind farm Dynamic equivalence Squirrel-Cage Induction Generator (SCIG) Genetic algorithm

Load identification in one dimensional structure based on hybrid finite element method

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Science China(Technological Sciences) 2017年第4期60卷 538-551页

作者： XUE XiaoFeng CHEN XueFeng ZHANG XingWu geng jia State Key Laboratory for Manufacturing System Engineering School of Mechanical Engineering Xi'an Jiaotong University Xi'an 710049 China

The new hybrid elements are proposed by combing modified Hermitian wavelet elements with ANASYS elements. Then hybrid elements are substituted into finite element formulations to solve the load identification. Transfer matrix can be constructed by using the inverse Newmark algorithm and hybrid finite element method. Loads can obtain through the responses and the transfer matrix. Load identification law was studied under different excitation cases in rod and Timoshenko *** method is adopted to solve ill-posed inverse problem of load identification. Compared with ANSYS results,hybrid elements and HCSWI elements can accurately identify the applied load. Numerical results show that the algorithm of hybrid elements is effective. The accuracy of hybrid elements and HCSWI elements can be verified by comparing the load identification result of ANASYS elements with the experiment data. Hermitian wavelet finite element methods have high accuracy advantage but it is difficult to apply the engineering practice. In practical engineering, complex structure can be analyzed by using the hybrid finite element methods which can be obtained the high accuracy in the crucial component.

关键词： hybrid finite element method Hermitian wavelet elements load identification regularization method

Redshift drift constraints on f（T） gravity

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Frontiers of physics 2015年第5期10卷 1-6页

作者： jia-jia geng Rui-Yun Guo Dong-Ze He Jing-Fei Zhang Xin Zhang Department of Physics College of Sciences Northeastern University Shenyang 110004 China Center for High Energy Physics Peking University Beijing 100080 China

We explore the impact of the Sandage-Loeb （SL） test on the precision of cosmological constraints for f（T） gravity theories. The SL test is an important supplement to current cosmological observations because it measures the redshift drift in the Lyman-α forest in the spectra of distant quasars, covering the ＂redshift desert＂ of 2 ≤ z ≤ 5. To avoid data inconsistency, we use the best-fit models based on current combined observational data as fiducial models to simulate 30 mock SL test data. We quantify the impact of these SL test data on parameter estimation for f（T） gravity theories. Two typical f（T） models are considered, the power-law model f（T）pL and the exponential-form model f（T）Exp. The results show that the SL test can effectively break the existing strong degeneracy between the present-day matter density Ωm and the Hubble constant Ho in other cosmological observations. For the considered f（T） models, a 30-year observation of the SL test can improve the constraint precision of Ωm and H0 enormously but cannot effectively improve the constraint precision of the model parameters.

关键词： redshift drift cosmological constraints dark energy modified gravity f(T) gravity

A designed locked nucleic acid-based nanopore for discriminating ctDNA and its coexisting analogue ncDNA

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Chinese Chemical Letters 2020年第1期31卷 172-176页

作者： Yuqin Huang You Lv jia geng Dan Xiao Cuisong Zhou College of Chemistry Sichuan UniversityChengdu 610064China Department of Laboratory Medicine State Key Laboratory of BiotherapyWest China HospitalSichuan University and Collaborative Innovation Center for BiotherapyChengdu 610041China

Circulating tumor DNA(ctDNA),carrying tumor-specific sequence mutations,is a promising biomarker for classification,diagnosis and prognosis of ***,there is still a great challenge in discriminating single-base difference between ctDNA and its coexisting analogue(normal circulating DNA,ncDNA)at a serum sample.A locked nucleic acid(LNA)probe combined with a-HL nanopore sensor was designed,which achieved a high signal-to-background ratio(SBR)of^8.34 × 10^3,as well as a significant discrimination capability(~12.3 times)of single-base diffe *** accurate discrimination strategy is label-free,convenient,selective and sensitive,which has great potential in the early diagnosis of diseases and biomedical research fields.

关键词： Single-base difference Simultaneous discrimination Nanopore Circulating tumor DNA Locked nucleic acid

Construction and Application of Multivariable Finite Element for Flat Shell Analysis

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Acta Mechanica Solida Sinica 2018年第4期31卷 391-404页

作者： Xingwu Zhang Yanfei He Robert X. Gao jia geng Xuefeng Chen jiawei Xiang State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong University Xi'an 710049 China School of Mechanical Engineering Xi ' an Jiaotong University Xi ' an 710049 China Department of Mechanical Engineering Case Western Reserve University Cleveland OH 44106 USA Zhejiang Provincial Key Laboratory of Laser Processing Robot/Key Laboratory of Laser Precision Processing & Detection Wenzhou University Wenzhou 325035 China

Based on B-spline wavelet on the interval （BSWI） and the multivariable generalized variational principle, the multivariable wavelet finite element for flat shell is constructed by combining the elastic plate element and the Mindlin plate element together. First, the elastic plate element formulation is derived from the generalized potential energy function. Due to its excellent numerical approximation property, BSWI is used as the interpolation function to separate the solving field variables. Second, the multivariable wavelet Mindlin plate element is deduced and constructed according to the multivariable generalized variational principle and BSWI. Third, by following the displacement compatibility requirement and the coordinate transformation method, the multivariable wavelet finite element for fiat shell is constructed. The novel advantage of the constructed element is that the solving precision and efficiency can be improved because the generalized displacement field variables and stress field variables are interpolated and solved independently. Finally, several numerical examples including bending and vibration analyses are given to verify the constructed element and method.

关键词： B-spline wavelet on the interval Elastic plate Mindlin plate Flat shell Multivariable

Prospect for Cosmological Parameter Estimation Using Future Hubble Parameter Measurements

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Communications in Theoretical Physics 2018年第10期70卷 445-450页

作者： jia-jia geng Rui-Yun Guo An-Zhong Wang Jing-Fei Zhang Xin Zhang Institute for Advanced Physics & Mathematics Zhejiang University of Technology Hangzhou 310032 China Department of Physics College of Sciences Northeastern University Shenyang 110004 China GCAP-CASPER Department of Physics Baylor University Waco TX 76798-7316 USA Center for High Energy Physics Peking University Beijing 100080 China Center for Gravitation and Cosmology Yangzhou University Yangzhou 225009 China

We constrain cosmological parameters using only Hubble parameter data and quantify the impact of future Hubble parameter measurements on parameter estimation for the most typical dark energy models. We first constrain cosmological parameters using 52 current Hubble parameter data including the Hubble constant measurement from the Hubble Space Telescope. Then we simulate the baryon acoustic oscillation signals from WFIRST(Wide-Field Infrared Survey Telescope) covering the redshift range of z ∈ [0.5, 2] and the redshift drift data from E-ELT(European Extremely Large Telescope) in the redshift range of z ∈ [2, 5]. It is shown that solely using the current Hubble parameter data could give fairly good constraints on cosmological parameters. Compared to the current Hubble parameter data, with the WFIRST observation the H(z) constraints on dark energy would be improved slightly, while with the E-ELT observation the H(z) constraints on dark energy is enormously improved.

关键词： dark energy cosmological parameter constraints Hubble parameter measurements

View-invariant human action recognition via robust locally adaptive multi-view learning

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Frontiers of Information Technology & Electronic Engineering 2015年第11期16卷 917-929页

作者： jia-geng FENG Jun XIAO Institute of Artificial Intelligence College of Computer Science and Technology Zhejiang University

Human action recognition is currently one of the most active research areas in computer vision. It has been widely used in many applications, such as intelligent surveillance, perceptual interface, and content-based video retrieval. However, some extrinsic factors are barriers for the development of action recognition; e.g., human actions may be observed from arbitrary camera viewpoints in realistic scene. Thus, view-invariant analysis becomes important for action recognition algorithms, and a number of researchers have paid much attention to this issue. In this paper, we present a multi-view learning approach to recognize human actions from different views. As most existing multi-view learning algorithms often suffer from the problem of lacking data adaptiveness in the nearest neighborhood graph construction procedure, a robust locally adaptive multi-view learning algorithm based on learning multiple local L 1-graphs is proposed. Moreover, an efficient iterative optimization method is proposed to solve the proposed objective function. Experiments on three public view-invariant action recognition datasets, i.e., ViHASi, IXMAS, and WVU, demonstrate data adaptiveness, effectiveness, and efficiency of our algorithm. More importantly, when the feature dimension is correctly selected （i.e., 〉60）, the proposed algorithm stably outperforms state-of-the-art counterparts and obtains about 6% improvement in recognition accuracy on the three datasets.

关键词： View-invariant Action recognition Multi-view learning Ll-norm Local learning

Transgene expression and differentiation of baculovirus-transduced adipose-derived stem cells from dystrophin-utrophin double knock-out mouse

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Neural Regeneration Research 2012年第22期7卷 1695-1702页

作者： Qiuling Li Qiongxiang Zhai jia geng Hui Zheng Fei Chen Jie Kong Cheng Zhang Department of Neurology FirstAffiliated Hospital Sun Yat-sen University Guangzhou 510080 Guangdong Province China Department of Pediatrics Guangdong General Hospital Guangdong Neuroscience Institute Guangdong Academy of Medical Sciences Guangzhou 510080 Guangdong Province China Department of Neurology First Affiliated Hospital Kunming Medical College Kunming 650032 Yunnan Province China Department of Neurology Nanfang Hospital Southern Medical University Guangzhou 510515 Guangdong Province China Center for Stem Cell Biology and Tissue Engineering Sun Yat-sen University Guangzhou 510085 Guangdong Province China

In this study, recombinant baculovirus carrying the microdystrophin and β-catenin genes was used to infect adipose-derived stem cells from a dystrophin-utrophin double knock-out mouse. Results showed that, after baculovirus transgene infection, microdystrophin and β-catenin genes were effectively expressed in adipose-derived stem cells from the dystrophin-utrophin double knock-out mouse. Furthermore, this transgenic expression promoted adipose-derived stem cell differentiation into muscle cells, but inhibited adipogenic differentiation. In addition, protein expression related to the microdystrophin and Wnt/β-catenin signaling pathway was upregulated. Our experimental findings indicate that baculovirus can successfully deliver the microdystrophin and β-catenin genes into adipose-derived stem cells, and the microdystrophin and Wnt/β-catenin signaling pathway plays an important role in myogenesis of adipose-derived stem cells in the dystrophin-utrophin double knock-out mouse.

关键词： baculovirus adipose-derived stem cells Duchenne muscular dystrophy microdystrophin β-catenin myogenesis gene therapy neural regeneration

A Convenient Synthesis of Aromatic Fluoride by Thermal Stable Pyridinium Phase-transfer Catalyst

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Chinese Chemical Letters 2002年第10期13卷 919-920页

作者： Ying Hong ZHU Hui LOU Ping LU jia geng LIU Xiao Ming ZHENG Chemistry Department Zhejiang UniversityHangzhou 310028

Using 4-Dialkylaminopyridinium salt as a thermal stable phase-transfer catalyst (PTC), the excellent results were obtained in the halogen-exchange fluorination.

关键词： 4-dialkylaminopyridinium salt phase-transfer catalyst fluorination